Commit Graph

63 Commits

Author SHA1 Message Date
Mauro Carvalho Chehab 8e2a46a40f docs: move remaining stuff under Documentation/*.txt to Documentation/staging
There are several files that I was unable to find a proper place
for them, and 3 ones that are still in plain old text format.

Let's place those stuff behind the carpet, as we'd like to keep the
root directory clean.

We can later discuss and move those into better places.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/11bd0d75e65a874f7c276a0aeab0fe13f3376f5f.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-19 14:17:05 -06:00
Daniel Bristot de Oliveira c2ba8a15f3 jump_label: Batch updates if arch supports it
If the architecture supports the batching of jump label updates, use it!

An easy way to see the benefits of this patch is switching the
schedstats on and off. For instance:

-------------------------- %< ----------------------------
  #!/bin/sh
  while [ true ]; do
      sysctl -w kernel.sched_schedstats=1
      sleep 2
      sysctl -w kernel.sched_schedstats=0
      sleep 2
  done
-------------------------- >% ----------------------------

while watching the IPI count:

-------------------------- %< ----------------------------
  # watch -n1 "cat /proc/interrupts | grep Function"
-------------------------- >% ----------------------------

With the current mode, it is possible to see +- 168 IPIs each 2 seconds,
while with this patch the number of IPIs goes to 3 each 2 seconds.

Regarding the performance impact of this patch set, I made two measurements:

    The time to update a key (the task that is causing the change)
    The time to run the int3 handler (the side effect on a thread that
                                      hits the code being changed)

The schedstats static key was chosen as the key to being switched on and off.
The reason being is that it is used in more than 56 places, in a hot path. The
change in the schedstats static key will be done with the following command:

while [ true ]; do
    sysctl -w kernel.sched_schedstats=1
    usleep 500000
    sysctl -w kernel.sched_schedstats=0
    usleep 500000
done

In this way, they key will be updated twice per second. To force the hit of the
int3 handler, the system will also run a kernel compilation with two jobs per
CPU. The test machine is a two nodes/24 CPUs box with an Intel Xeon processor
@2.27GHz.

Regarding the update part, on average, the regular kernel takes 57 ms to update
the schedstats key, while the kernel with the batch updates takes just 1.4 ms
on average. Although it seems to be too good to be true, it makes sense: the
schedstats key is used in 56 places, so it was expected that it would take
around 56 times to update the keys with the current implementation, as the
IPIs are the most expensive part of the update.

Regarding the int3 handler, the non-batch handler takes 45 ns on average, while
the batch version takes around 180 ns. At first glance, it seems to be a high
value. But it is not, considering that it is doing 56 updates, rather than one!
It is taking four times more, only. This gain is possible because the patch
uses a binary search in the vector: log2(56)=5.8. So, it was expected to have
an overhead within four times.

(voice of tv propaganda) But, that is not all! As the int3 handler keeps on for
a shorter period (because the update part is on for a shorter time), the number
of hits in the int3 handler decreased by 10%.

The question then is: Is it worth paying the price of "135 ns" more in the int3
handler?

Considering that, in this test case, we are saving the handling of 53 IPIs,
that takes more than these 135 ns, it seems to be a meager price to be paid.
Moreover, the test case was forcing the hit of the int3, in practice, it
does not take that often. While the IPI takes place on all CPUs, hitting
the int3 handler or not!

For instance, in an isolated CPU with a process running in user-space
(nohz_full use-case), the chances of hitting the int3 handler is barely zero,
while there is no way to avoid the IPIs. By bounding the IPIs, we are improving
a lot this scenario.

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/acc891dbc2dbc9fd616dd680529a2337b1d1274c.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-17 12:09:22 +02:00
Masahiro Yamada e9666d10a5 jump_label: move 'asm goto' support test to Kconfig
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".

The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:

  #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
  # define HAVE_JUMP_LABEL
  #endif

We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.

Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
2019-01-06 09:46:51 +09:00
Ard Biesheuvel 1948367768 jump_label: Annotate entries that operate on __init code earlier
Jump table entries are mostly read-only, with the exception of the
init and module loader code that defuses entries that point into init
code when the code being referred to is freed.

For robustness, it would be better to move these entries into the
ro_after_init section, but clearing the 'code' member of each jump
table entry referring to init code at module load time races with the
module_enable_ro() call that remaps the ro_after_init section read
only, so we'd like to do it earlier.

So given that whether such an entry refers to init code can be decided
much earlier, we can pull this check forward. Since we may still need
the code entry at this point, let's switch to setting a low bit in the
'key' member just like we do to annotate the default state of a jump
table entry.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
Link: https://lkml.kernel.org/r/20180919065144.25010-8-ard.biesheuvel@linaro.org
2018-09-27 17:56:48 +02:00
Ard Biesheuvel 50ff18ab49 jump_label: Implement generic support for relative references
To reduce the size taken up by absolute references in jump label
entries themselves and the associated relocation records in the
.init segment, add support for emitting them as relative references
instead.

Note that this requires some extra care in the sorting routine, given
that the offsets change when entries are moved around in the jump_entry
table.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
Link: https://lkml.kernel.org/r/20180919065144.25010-3-ard.biesheuvel@linaro.org
2018-09-27 17:56:47 +02:00
Ard Biesheuvel 9ae033aca8 jump_label: Abstract jump_entry member accessors
In preparation of allowing architectures to use relative references
in jump_label entries [which can dramatically reduce the memory
footprint], introduce abstractions for references to the 'code' and
'key' members of struct jump_entry.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
Link: https://lkml.kernel.org/r/20180919065144.25010-2-ard.biesheuvel@linaro.org
2018-09-27 17:56:46 +02:00
Chris von Recklinghausen b5cb15d937 usercopy: Allow boot cmdline disabling of hardening
Enabling HARDENED_USERCOPY may cause measurable regressions in networking
performance: up to 8% under UDP flood.

I ran a small packet UDP flood using pktgen vs. a host b2b connected. On
the receiver side the UDP packets are processed by a simple user space
process that just reads and drops them:

https://github.com/netoptimizer/network-testing/blob/master/src/udp_sink.c

Not very useful from a functional PoV, but it helps to pin-point
bottlenecks in the networking stack.

When running a kernel with CONFIG_HARDENED_USERCOPY=y, I see a 5-8%
regression in the receive tput, compared to the same kernel without this
option enabled.

With CONFIG_HARDENED_USERCOPY=y, perf shows ~6% of CPU time spent
cumulatively in __check_object_size (~4%) and __virt_addr_valid (~2%).

The call-chain is:

__GI___libc_recvfrom
entry_SYSCALL_64_after_hwframe
do_syscall_64
__x64_sys_recvfrom
__sys_recvfrom
inet_recvmsg
udp_recvmsg
__check_object_size

udp_recvmsg() actually calls copy_to_iter() (inlined) and the latters
calls check_copy_size() (again, inlined).

A generic distro may want to enable HARDENED_USERCOPY in their default
kernel config, but at the same time, such distro may want to be able to
avoid the performance penalties in with the default configuration and
disable the stricter check on a per-boot basis.

This change adds a boot parameter that conditionally disables
HARDENED_USERCOPY via "hardened_usercopy=off".

Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-07-04 08:04:52 -07:00
Josh Poimboeuf 578ae447e7 jump_label: Disable jump labels in __exit code
With the following commit:

  3335224470 ("jump_label: Explicitly disable jump labels in __init code")

... we explicitly disabled jump labels in __init code, so they could be
detected and not warned about in the following commit:

  dc1dd184c2 ("jump_label: Warn on failed jump_label patching attempt")

In-kernel __exit code has the same issue.  It's never used, so it's
freed along with the rest of initmem.  But jump label entries in __exit
code aren't explicitly disabled, so we get the following warning when
enabling pr_debug() in __exit code:

  can't patch jump_label at dmi_sysfs_exit+0x0/0x2d
  WARNING: CPU: 0 PID: 22572 at kernel/jump_label.c:376 __jump_label_update+0x9d/0xb0

Fix the warning by disabling all jump labels in initmem (which includes
both __init and __exit code).

Reported-and-tested-by: Li Wang <liwang@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: dc1dd184c2 ("jump_label: Warn on failed jump_label patching attempt")
Link: http://lkml.kernel.org/r/7121e6e595374f06616c505b6e690e275c0054d1.1521483452.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-20 08:57:17 +01:00
Josh Poimboeuf 3335224470 jump_label: Explicitly disable jump labels in __init code
After initmem has been freed, any jump labels in __init code are
prevented from being written to by the kernel_text_address() check in
__jump_label_update().  However, this check is quite broad.  If
kernel_text_address() were to return false for any other reason, the
jump label write would fail silently with no warning.

For jump labels in module init code, entry->code is set to zero to
indicate that the entry is disabled.  Do the same thing for core kernel
init code.  This makes the behavior more consistent, and will also make
it more straightforward to detect non-init jump label write failures in
the next patch.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/c52825c73f3a174e8398b6898284ec20d4deb126.1519051220.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-21 16:54:05 +01:00
Peter Zijlstra 81dcf89f03 jump_label: Add branch hints to static_branch_{un,}likely()
For some reason these were missing, I've not observed this patch
making a difference in the few code locations I checked, but this
makes sense.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-06 10:28:57 +01:00
Peter Zijlstra ce48c14649 sched/core: Fix cpu.max vs. cpuhotplug deadlock
Tejun reported the following cpu-hotplug lock (percpu-rwsem) read recursion:

  tg_set_cfs_bandwidth()
    get_online_cpus()
      cpus_read_lock()

    cfs_bandwidth_usage_inc()
      static_key_slow_inc()
        cpus_read_lock()

Reported-by: Tejun Heo <tj@kernel.org>
Tested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180122215328.GP3397@worktop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-24 10:03:44 +01:00
Ingo Molnar 8c5db92a70 Merge branch 'linus' into locking/core, to resolve conflicts
Conflicts:
	include/linux/compiler-clang.h
	include/linux/compiler-gcc.h
	include/linux/compiler-intel.h
	include/uapi/linux/stddef.h

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-07 10:32:44 +01:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Borislav Petkov 5cdda5117e locking/static_keys: Improve uninitialized key warning
Right now it says:

  static_key_disable_cpuslocked used before call to jump_label_init
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:161 static_key_disable_cpuslocked+0x68/0x70
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 4.14.0-rc5+ #1
  Hardware name: SGI.COM C2112-4GP3/X10DRT-P-Series, BIOS 2.0a 05/09/2016
  task: ffffffff81c0e480 task.stack: ffffffff81c00000
  RIP: 0010:static_key_disable_cpuslocked+0x68/0x70
  RSP: 0000:ffffffff81c03ef0 EFLAGS: 00010096 ORIG_RAX: 0000000000000000
  RAX: 0000000000000041 RBX: ffffffff81c32680 RCX: ffffffff81c5cbf8
  RDX: 0000000000000001 RSI: 0000000000000092 RDI: 0000000000000002
  RBP: ffff88807fffd240 R08: 726f666562206465 R09: 0000000000000136
  R10: 0000000000000000 R11: 696e695f6c656261 R12: ffffffff82158900
  R13: ffffffff8215f760 R14: 0000000000000001 R15: 0000000000000008
  FS:  0000000000000000(0000) GS:ffff883f7f400000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffff88807ffff000 CR3: 0000000001c09000 CR4: 00000000000606b0
  Call Trace:
   static_key_disable+0x16/0x20
   start_kernel+0x15a/0x45d
   ? load_ucode_intel_bsp+0x11/0x2d
   secondary_startup_64+0xa5/0xb0
  Code: 48 c7 c7 a0 15 cf 81 e9 47 53 4b 00 48 89 df e8 5f fc ff ff eb e8 48 c7 c6 \
	c0 97 83 81 48 c7 c7 d0 ff a2 81 31 c0 e8 c5 9d f5 ff <0f> ff eb a7 0f ff eb \
	b0 e8 eb a2 4b 00 53 48 89 fb e8 42 0e f0

but it doesn't tell me which key it is. So dump the key's name too:

  static_key_disable_cpuslocked(): static key 'virt_spin_lock_key' used before call to jump_label_init()

And that makes pinpointing which key is causing that a lot easier.

 include/linux/jump_label.h           |   14 +++++++-------
 include/linux/jump_label_ratelimit.h |    6 +++---
 kernel/jump_label.c                  |   14 +++++++-------
 3 files changed, 17 insertions(+), 17 deletions(-)

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171018152428.ffjgak4o25f7ept6@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-19 07:49:14 +02:00
Marc Zyngier 5a40527f8f jump_label: Provide hotplug context variants
As using the normal static key API under the hotplug lock is
pretty much impossible, let's provide a variant of some of them
that require the hotplug lock to have already been taken.

These function are only meant to be used in CPU hotplug callbacks.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170801080257.5056-4-marc.zyngier@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:28:59 +02:00
Paolo Bonzini 1dbb6704de jump_label: Fix concurrent static_key_enable/disable()
static_key_enable/disable are trying to cap the static key count to
0/1.  However, their use of key->enabled is outside jump_label_lock
so they do not really ensure that.

Rewrite them to do a quick check for an already enabled (respectively,
already disabled), and then recheck under the jump label lock.  Unlike
static_key_slow_inc/dec, a failed check under the jump label lock does
not modify key->enabled.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1501601046-35683-2-git-send-email-pbonzini@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:28:56 +02:00
Linus Torvalds f26db9649a There was some breakage with the changes for jump labels in the 4.11 merge
window. Namely powerpc broke as jump labels uses the two LSB bits as flags
 in initialization. A check was added to make sure that all jump label
 entries were 4 bytes aligned, but powerpc didn't work that way for modules.
 Adding an alignment in the module linker script appeared to be the best
 solution.
 
 Jump labels also added an anonymous union to access those LSB bits as a
 normal long. But because this structure had static initialization, it broke
 older compilers that could not statically initialize anonymous unions
 without brackets.
 
 The command line parameter for setting function graph filter broke the
 "EMPTY_HASH" descriptor by modifying it instead of creating a new hash to
 hold the entries.
 
 The command line parameter ftrace_graph_max_depth was added to allow its
 setting at boot time. It uses existing code and only the command line hook
 was added. This is not really a fix, but as it uses existing code without
 affecting anything else, I added it to this release. It was ready before the
 merge window closed, but I wanted to let it sit in linux-next for a couple
 of days first.
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Merge tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "There was some breakage with the changes for jump labels in the 4.11
  merge window:

   - powerpc broke as jump labels uses the two LSB bits as flags in
     initialization.

     A check was added to make sure that all jump label entries were 4
     bytes aligned, but powerpc didn't work that way for modules. Adding
     an alignment in the module linker script appeared to be the best
     solution.

   - Jump labels also added an anonymous union to access those LSB bits
     as a normal long. But because this structure had static
     initialization, it broke older compilers that could not statically
     initialize anonymous unions without brackets.

   - The command line parameter for setting function graph filter broke
     the "EMPTY_HASH" descriptor by modifying it instead of creating a
     new hash to hold the entries.

   - The command line parameter ftrace_graph_max_depth was added to
     allow its setting at boot time. It uses existing code and only the
     command line hook was added.

     This is not really a fix, but as it uses existing code without
     affecting anything else, I added it to this release. It was ready
     before the merge window closed, but I wanted to let it sit in
     linux-next for a couple of days first"

* tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/graph: Add ftrace_graph_max_depth kernel parameter
  tracing: Add #undef to fix compile error
  jump_label: Add comment about initialization order for anonymous unions
  jump_label: Fix anonymous union initialization
  module: set __jump_table alignment to 8
  ftrace/graph: Do not modify the EMPTY_HASH for the function_graph filter
  tracing: Fix code comment for ftrace_ops_get_func()
2017-03-07 09:37:28 -08:00
Steven Rostedt (VMware) b17ef2ed62 jump_label: Add comment about initialization order for anonymous unions
Commit 3821fd35b5 ("jump_label: Reduce the size of struct static_key")
broke old compilers that could not handle static initialization of anonymous
unions. Boris fixed it with a patch that added brackets around the static
initializer. But this creates a dependency between those initializers and
the structure's order of its fields. Document this dependency in case new
fields are added to struct static_key in the future.

Noted-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Suggested-by: Chris Mason <clm@fb.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-03-03 09:45:00 -05:00
Boris Ostrovsky cd8d860dcc jump_label: Fix anonymous union initialization
Pre-4.6 gcc do not allow direct static initialization of members of
anonymous structs/unions. After commit 3821fd35b5 ("jump_label:
Reduce the size of struct static_key") STATIC_KEY_INIT_{TRUE|FALSE}
definitions cannot be compiled with those older compilers.

Placing initializers inside curved brackets works around this problem.

Link: http://lkml.kernel.org/r/1488299542-30765-1-git-send-email-boris.ostrovsky@oracle.com

Fixes: 3821fd35b5 ("jump_label: Reduce the size of struct static_key")
Reviewed-by: Jason Baron <jbaron@akamai.com>
Compiled-by: Chris Mason <clm@fb.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-03-03 09:44:59 -05:00
Linus Torvalds 79b17ea740 This release has no new tracing features, just clean ups, minor fixes
and small optimizations.
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Merge tag 'trace-v4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "This release has no new tracing features, just clean ups, minor fixes
  and small optimizations"

* tag 'trace-v4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (25 commits)
  tracing: Remove outdated ring buffer comment
  tracing/probes: Fix a warning message to show correct maximum length
  tracing: Fix return value check in trace_benchmark_reg()
  tracing: Use modern function declaration
  jump_label: Reduce the size of struct static_key
  tracing/probe: Show subsystem name in messages
  tracing/hwlat: Update old comment about migration
  timers: Make flags output in the timer_start tracepoint useful
  tracing: Have traceprobe_probes_write() not access userspace unnecessarily
  tracing: Have COMM event filter key be treated as a string
  ftrace: Have set_graph_function handle multiple functions in one write
  ftrace: Do not hold references of ftrace_graph_{notrace_}hash out of graph_lock
  tracing: Reset parser->buffer to allow multiple "puts"
  ftrace: Have set_graph_functions handle write with RDWR
  ftrace: Reset fgd->hash in ftrace_graph_write()
  ftrace: Replace (void *)1 with a meaningful macro name FTRACE_GRAPH_EMPTY
  ftrace: Create a slight optimization on searching the ftrace_hash
  tracing: Add ftrace_hash_key() helper function
  ftrace: Convert graph filter to use hash tables
  ftrace: Expose ftrace_hash_empty and ftrace_lookup_ip
  ...
2017-02-27 13:26:17 -08:00
Jason Baron 3821fd35b5 jump_label: Reduce the size of struct static_key
The static_key->next field goes mostly unused. The field is used for
associating module uses with a static key. Most uses of struct static_key
define a static key in the core kernel and make use of it entirely within
the core kernel, or define the static key in a module and make use of it
only from within that module. In fact, of the ~3,000 static keys defined,
I found only about 5 or so that did not fit this pattern.

Thus, we can remove the static_key->next field entirely and overload
the static_key->entries field. That is, when all the static_key uses
are contained within the same module, static_key->entries continues
to point to those uses. However, if the static_key uses are not contained
within the module where the static_key is defined, then we allocate a
struct static_key_mod, store a pointer to the uses within that
struct static_key_mod, and have the static key point at the static_key_mod.
This does incur some extra memory usage when a static_key is used in a
module that does not define it, but since there are only a handful of such
cases there is a net savings.

In order to identify if the static_key->entries pointer contains a
struct static_key_mod or a struct jump_entry pointer, bit 1 of
static_key->entries is set to 1 if it points to a struct static_key_mod and
is 0 if it points to a struct jump_entry. We were already using bit 0 in a
similar way to store the initial value of the static_key. This does mean
that allocations of struct static_key_mod and that the struct jump_entry
tables need to be at least 4-byte aligned in memory. As far as I can tell
all arches meet this criteria.

For my .config, the patch increased the text by 778 bytes, but reduced
the data + bss size by 14912, for a net savings of 14,134 bytes.

   text	   data	    bss	    dec	    hex	filename
8092427	5016512	 790528	13899467	 d416cb	vmlinux.pre
8093205	5001600	 790528	13885333	 d3df95	vmlinux.post

Link: http://lkml.kernel.org/r/1486154544-4321-1-git-send-email-jbaron@akamai.com

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-02-15 09:02:26 -05:00
Luis R. Rodriguez 85b36c931f jump_labels: Move header guard #endif down where it belongs
The ending header guard is misplaced. This has no
functional change, this is just an eye-sore.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: bp@suse.de
Cc: catalin.marinas@arm.com
Cc: jbaron@akamai.com
Cc: pbonzini@redhat.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/20170118173804.16281-1-mcgrof@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-19 08:40:44 +01:00
Linus Torvalds e606d81d2d Merge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RAS updates from Ingo Molnar:
 "The main changes were:

   - Lots of enhancements for AMD SMCA (Scalable MCA
     features/extensions) systems: extract, decode and print more
     hardware error information and add matching support on the
     injection/testing side as well. (Yazn Ghannam)

   - Various MCE handling improvements on modern Intel Xeons. (Tony
     Luck)

   - Plus misc fixes and enhancements"

* 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  x86/RAS/mce_amd_inj: Remove debugfs dir recursively on exit
  x86/RAS/mce_amd_inj: Fix signed wrap around when decrementing index 'i'
  x86/RAS/mce_amd_inj: Fix some W= warnings
  x86/MCE/AMD, EDAC: Handle reserved bank 4 on Fam17h properly
  x86/mce/AMD: Extract the error address on SMCA systems
  x86/mce, EDAC/mce_amd: Print MCA_SYND and MCA_IPID during MCE on SMCA systems
  x86/mce/AMD: Save MCA_IPID in MCE struct on SMCA systems
  x86/mce/AMD: Ensure the deferred error interrupt is of type APIC on SMCA systems
  x86/mce/AMD: Update sysfs bank names for SMCA systems
  x86/mce/AMD, EDAC/mce_amd: Define and use tables for known SMCA IP types
  EDAC/mce_amd: Use SMCA prefix for error descriptions arrays
  EDAC/mce_amd: Add missing SMCA error descriptions
  x86/mce/AMD: Read MSRs on the CPU allocating the threshold blocks
  x86/RAS: Add syndrome support to mce_amd_inj
  EDAC/mce_amd: Print syndrome register value on SMCA systems
  x86/mce: Add support for new MCA_SYND register
  x86/mce/AMD: Use msr_ops.misc() in allocate_threshold_blocks()
  x86/mce: Drop X86_FEATURE_MCE_RECOVERY and the related model string test
  x86/mce: Improve memcpy_mcsafe()
  x86/mce: Add PCI quirks to identify Xeons with machine check recovery
  ...
2016-10-03 13:22:39 -07:00
Catalin Marinas ef0da55a84 jump_labels: Allow array initialisers
The static key API is currently designed around single variable
definitions. There are cases where an array of static keys is desirable,
so extend the API to allow this rather than using the internal static
key implementation directly.

Cc: Jason Baron <jbaron@akamai.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Suggested-by: Dave P Martin <Dave.Martin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-09-07 09:41:11 +01:00
Tony Luck b8fb03785d locking/static_keys: Provide DECLARE and well as DEFINE macros
We will need to provide declarations of static keys in header
files. Provide DECLARE_STATIC_KEY_{TRUE,FALSE} macros.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/816881cf85bd3cf13385d212882618f38a3b5d33.1472754711.git.tony.luck@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-05 11:47:31 +02:00
Jason Baron 1f69bf9c61 jump_label: remove bug.h, atomic.h dependencies for HAVE_JUMP_LABEL
The current jump_label.h includes bug.h for things such as WARN_ON().
This makes the header problematic for inclusion by kernel.h or any
headers that kernel.h includes, since bug.h includes kernel.h (circular
dependency).  The inclusion of atomic.h is similarly problematic.  Thus,
this should make jump_label.h 'includable' from most places.

Link: http://lkml.kernel.org/r/7060ce35ddd0d20b33bf170685e6b0fab816bdf2.1467837322.git.jbaron@akamai.com
Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-04 08:50:07 -04:00
Paolo Bonzini 4c5ea0a9cd locking/static_key: Fix concurrent static_key_slow_inc()
The following scenario is possible:

    CPU 1                                   CPU 2
    static_key_slow_inc()
     atomic_inc_not_zero()
      -> key.enabled == 0, no increment
     jump_label_lock()
     atomic_inc_return()
      -> key.enabled == 1 now
                                            static_key_slow_inc()
                                             atomic_inc_not_zero()
                                              -> key.enabled == 1, inc to 2
                                             return
                                            ** static key is wrong!
     jump_label_update()
     jump_label_unlock()

Testing the static key at the point marked by (**) will follow the
wrong path for jumps that have not been patched yet.  This can
actually happen when creating many KVM virtual machines with userspace
LAPIC emulation; just run several copies of the following program:

    #include <fcntl.h>
    #include <unistd.h>
    #include <sys/ioctl.h>
    #include <linux/kvm.h>

    int main(void)
    {
        for (;;) {
            int kvmfd = open("/dev/kvm", O_RDONLY);
            int vmfd = ioctl(kvmfd, KVM_CREATE_VM, 0);
            close(ioctl(vmfd, KVM_CREATE_VCPU, 1));
            close(vmfd);
            close(kvmfd);
        }
        return 0;
    }

Every KVM_CREATE_VCPU ioctl will attempt a static_key_slow_inc() call.
The static key's purpose is to skip NULL pointer checks and indeed one
of the processes eventually dereferences NULL.

As explained in the commit that introduced the bug:

  706249c222 ("locking/static_keys: Rework update logic")

jump_label_update() needs key.enabled to be true.  The solution adopted
here is to temporarily make key.enabled == -1, and use go down the
slow path when key.enabled <= 0.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v4.3+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 706249c222 ("locking/static_keys: Rework update logic")
Link: http://lkml.kernel.org/r/1466527937-69798-1-git-send-email-pbonzini@redhat.com
[ Small stylistic edits to the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24 08:23:16 +02:00
Peter Zijlstra 90eec103b9 treewide: Remove old email address
There were still a number of references to my old Red Hat email
address in the kernel source. Remove these while keeping the
Red Hat copyright notices intact.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23 09:44:58 +01:00
Linus Torvalds 69234acee5 Merge branch 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "The cgroup core saw several significant updates this cycle:

   - percpu_rwsem for threadgroup locking is reinstated.  This was
     temporarily dropped due to down_write latency issues.  Oleg's
     rework of percpu_rwsem which is scheduled to be merged in this
     merge window resolves the issue.

   - On the v2 hierarchy, when controllers are enabled and disabled, all
     operations are atomic and can fail and revert cleanly.  This allows
     ->can_attach() failure which is necessary for cpu RT slices.

   - Tasks now stay associated with the original cgroups after exit
     until released.  This allows tracking resources held by zombies
     (e.g.  pids) and makes it easy to find out where zombies came from
     on the v2 hierarchy.  The pids controller was broken before these
     changes as zombies escaped the limits; unfortunately, updating this
     behavior required too many invasive changes and I don't think it's
     a good idea to backport them, so the pids controller on 4.3, the
     first version which included the pids controller, will stay broken
     at least until I'm sure about the cgroup core changes.

   - Optimization of a couple common tests using static_key"

* 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (38 commits)
  cgroup: fix race condition around termination check in css_task_iter_next()
  blkcg: don't create "io.stat" on the root cgroup
  cgroup: drop cgroup__DEVEL__legacy_files_on_dfl
  cgroup: replace error handling in cgroup_init() with WARN_ON()s
  cgroup: add cgroup_subsys->free() method and use it to fix pids controller
  cgroup: keep zombies associated with their original cgroups
  cgroup: make css_set_rwsem a spinlock and rename it to css_set_lock
  cgroup: don't hold css_set_rwsem across css task iteration
  cgroup: reorganize css_task_iter functions
  cgroup: factor out css_set_move_task()
  cgroup: keep css_set and task lists in chronological order
  cgroup: make cgroup_destroy_locked() test cgroup_is_populated()
  cgroup: make css_sets pin the associated cgroups
  cgroup: relocate cgroup_[try]get/put()
  cgroup: move check_for_release() invocation
  cgroup: replace cgroup_has_tasks() with cgroup_is_populated()
  cgroup: make cgroup->nr_populated count the number of populated css_sets
  cgroup: remove an unused parameter from cgroup_task_migrate()
  cgroup: fix too early usage of static_branch_disable()
  cgroup: make cgroup_update_dfl_csses() migrate all target processes atomically
  ...
2015-11-05 14:51:32 -08:00
Tejun Heo fa128fd735 jump_label: make static_key_enabled() work on static_key_true/false types too
static_key_enabled() can be used on struct static_key but not on its
wrapper types static_key_true and static_key_false.  The function is
useful for debugging and management of static keys.  Update it so that
it can be used for the wrapper types too.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
2015-09-18 11:56:28 -04:00
Jonathan Corbet 1975dbc276 locking/static_keys: Fix up the static keys documentation
Fix a few small mistakes in the static key documentation and
delete an unneeded sentence.

Suggested-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150914171105.511e1e21@lwn.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-15 07:12:06 +02:00
Jonathan Corbet edcd591c77 locking/static_keys: Fix a silly typo
Commit:

  412758cb26 ("jump label, locking/static_keys: Update docs")

introduced a typo that might as well get fixed.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150907131803.54c027e1@lwn.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-08 09:02:17 +02:00
Jason Baron 412758cb26 jump label, locking/static_keys: Update docs
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: bp@alien8.de
Cc: davem@davemloft.net
Cc: ddaney@caviumnetworks.com
Cc: heiko.carstens@de.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: liuj97@gmail.com
Cc: luto@amacapital.net
Cc: michael@ellerman.id.au
Cc: rabin@rab.in
Cc: ralf@linux-mips.org
Cc: rostedt@goodmis.org
Cc: vbabka@suse.cz
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/6b50f2f6423a2244f37f4b1d2d6c211b9dcdf4f8.1438227999.git.jbaron@akamai.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 11:51:14 +02:00
Peter Zijlstra 11276d5306 locking/static_keys: Add a new static_key interface
There are various problems and short-comings with the current
static_key interface:

 - static_key_{true,false}() read like a branch depending on the key
   value, instead of the actual likely/unlikely branch depending on
   init value.

 - static_key_{true,false}() are, as stated above, tied to the
   static_key init values STATIC_KEY_INIT_{TRUE,FALSE}.

 - we're limited to the 2 (out of 4) possible options that compile to
   a default NOP because that's what our arch_static_branch() assembly
   emits.

So provide a new static_key interface:

  DEFINE_STATIC_KEY_TRUE(name);
  DEFINE_STATIC_KEY_FALSE(name);

Which define a key of different types with an initial true/false
value.

Then allow:

   static_branch_likely()
   static_branch_unlikely()

to take a key of either type and emit the right instruction for the
case.

This means adding a second arch_static_branch_jump() assembly helper
which emits a JMP per default.

In order to determine the right instruction for the right state,
encode the branch type in the LSB of jump_entry::key.

This is the final step in removing the naming confusion that has led to
a stream of avoidable bugs such as:

  a833581e37 ("x86, perf: Fix static_key bug in load_mm_cr4()")

... but it also allows new static key combinations that will give us
performance enhancements in the subsequent patches.

Tested-by: Rabin Vincent <rabin@rab.in> # arm
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> # ppc
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # s390
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 11:34:15 +02:00
Peter Zijlstra e33886b38c locking/static_keys: Add static_key_{en,dis}able() helpers
Add two helpers to make it easier to treat the refcount as boolean.

Suggested-by: Jason Baron <jasonbaron0@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 11:34:14 +02:00
Peter Zijlstra a1efb01fec jump_label, locking/static_keys: Rename JUMP_LABEL_TYPE_* and related helpers to the static_key* pattern
Rename the JUMP_LABEL_TYPE_* macros to be JUMP_TYPE_* and move the
inline helpers into kernel/jump_label.c, since that's the only place
they're ever used.

Also rename the helpers where it's all about static keys.

This is the second step in removing the naming confusion that has led to
a stream of avoidable bugs such as:

  a833581e37 ("x86, perf: Fix static_key bug in load_mm_cr4()")

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 11:34:13 +02:00
Peter Zijlstra 76b235c6bc jump_label: Rename JUMP_LABEL_{EN,DIS}ABLE to JUMP_LABEL_{JMP,NOP}
Since we've already stepped away from ENABLE is a JMP and DISABLE is a
NOP with the branch_default bits, and are going to make it even worse,
rename it to make it all clearer.

This way we don't mix multiple levels of logic attributes, but have a
plain 'physical' name for what the current instruction patching status
of a jump label is.

This is a first step in removing the naming confusion that has led to
a stream of avoidable bugs such as:

  a833581e37 ("x86, perf: Fix static_key bug in load_mm_cr4()")

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
[ Beefed up the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 11:34:12 +02:00
Anton Blanchard c0ccf6f99e jump_label: Allow jump labels to be used in assembly
To use jump labels in assembly we need the HAVE_JUMP_LABEL
define, so we select a fallback version if the toolchain does
not support them.

Modify linux/jump_label.h so it can be included by assembly
files. We also need to add -DCC_HAVE_ASM_GOTO to KBUILD_AFLAGS.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: catalin.marinas@arm.com
Cc: davem@davemloft.net
Cc: heiko.carstens@de.ibm.com
Cc: jbaron@akamai.com
Cc: linux@arm.linux.org.uk
Cc: linuxppc-dev@lists.ozlabs.org
Cc: liuj97@gmail.com
Cc: mgorman@suse.de
Cc: mmarek@suse.cz
Cc: mpe@ellerman.id.au
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: rostedt@goodmis.org
Cc: schwidefsky@de.ibm.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1428551492-21977-2-git-send-email-anton@samba.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-09 09:40:24 +02:00
Ingo Molnar fd3cbdc0d1 jump_label: Fix small typos in the documentation
Was reading through the documentation of this code and noticed
a few typos, missing commas, etc.

Cc: Jason Baron <jbaron@akamai.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-08-10 09:00:16 +02:00
Mel Gorman ea5e9539ab include/linux/jump_label.h: expose the reference count
This patch exposes the jump_label reference count in preparation for the
next patch.  cpusets cares about both the jump_label being enabled and how
many users of the cpusets there currently are.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:08 -07:00
Jiang Liu f4be8433fc jump_label: use defined macros instead of hard-coding for better readability
Use macro JUMP_LABEL_TRUE_BRANCH instead of hard-coding for better
readability.

Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-01-08 15:23:53 +00:00
Linus Torvalds 42a2d923cc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:

 1) The addition of nftables.  No longer will we need protocol aware
    firewall filtering modules, it can all live in userspace.

    At the core of nftables is a, for lack of a better term, virtual
    machine that executes byte codes to inspect packet or metadata
    (arriving interface index, etc.) and make verdict decisions.

    Besides support for loading packet contents and comparing them, the
    interpreter supports lookups in various datastructures as
    fundamental operations.  For example sets are supports, and
    therefore one could create a set of whitelist IP address entries
    which have ACCEPT verdicts attached to them, and use the appropriate
    byte codes to do such lookups.

    Since the interpreted code is composed in userspace, userspace can
    do things like optimize things before giving it to the kernel.

    Another major improvement is the capability of atomically updating
    portions of the ruleset.  In the existing netfilter implementation,
    one has to update the entire rule set in order to make a change and
    this is very expensive.

    Userspace tools exist to create nftables rules using existing
    netfilter rule sets, but both kernel implementations will need to
    co-exist for quite some time as we transition from the old to the
    new stuff.

    Kudos to Patrick McHardy, Pablo Neira Ayuso, and others who have
    worked so hard on this.

 2) Daniel Borkmann and Hannes Frederic Sowa made several improvements
    to our pseudo-random number generator, mostly used for things like
    UDP port randomization and netfitler, amongst other things.

    In particular the taus88 generater is updated to taus113, and test
    cases are added.

 3) Support 64-bit rates in HTB and TBF schedulers, from Eric Dumazet
    and Yang Yingliang.

 4) Add support for new 577xx tigon3 chips to tg3 driver, from Nithin
    Sujir.

 5) Fix two fatal flaws in TCP dynamic right sizing, from Eric Dumazet,
    Neal Cardwell, and Yuchung Cheng.

 6) Allow IP_TOS and IP_TTL to be specified in sendmsg() ancillary
    control message data, much like other socket option attributes.
    From Francesco Fusco.

 7) Allow applications to specify a cap on the rate computed
    automatically by the kernel for pacing flows, via a new
    SO_MAX_PACING_RATE socket option.  From Eric Dumazet.

 8) Make the initial autotuned send buffer sizing in TCP more closely
    reflect actual needs, from Eric Dumazet.

 9) Currently early socket demux only happens for TCP sockets, but we
    can do it for connected UDP sockets too.  Implementation from Shawn
    Bohrer.

10) Refactor inet socket demux with the goal of improving hash demux
    performance for listening sockets.  With the main goals being able
    to use RCU lookups on even request sockets, and eliminating the
    listening lock contention.  From Eric Dumazet.

11) The bonding layer has many demuxes in it's fast path, and an RCU
    conversion was started back in 3.11, several changes here extend the
    RCU usage to even more locations.  From Ding Tianhong and Wang
    Yufen, based upon suggestions by Nikolay Aleksandrov and Veaceslav
    Falico.

12) Allow stackability of segmentation offloads to, in particular, allow
    segmentation offloading over tunnels.  From Eric Dumazet.

13) Significantly improve the handling of secret keys we input into the
    various hash functions in the inet hashtables, TCP fast open, as
    well as syncookies.  From Hannes Frederic Sowa.  The key fundamental
    operation is "net_get_random_once()" which uses static keys.

    Hannes even extended this to ipv4/ipv6 fragmentation handling and
    our generic flow dissector.

14) The generic driver layer takes care now to set the driver data to
    NULL on device removal, so it's no longer necessary for drivers to
    explicitly set it to NULL any more.  Many drivers have been cleaned
    up in this way, from Jingoo Han.

15) Add a BPF based packet scheduler classifier, from Daniel Borkmann.

16) Improve CRC32 interfaces and generic SKB checksum iterators so that
    SCTP's checksumming can more cleanly be handled.  Also from Daniel
    Borkmann.

17) Add a new PMTU discovery mode, IP_PMTUDISC_INTERFACE, which forces
    using the interface MTU value.  This helps avoid PMTU attacks,
    particularly on DNS servers.  From Hannes Frederic Sowa.

18) Use generic XPS for transmit queue steering rather than internal
    (re-)implementation in virtio-net.  From Jason Wang.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1622 commits)
  random32: add test cases for taus113 implementation
  random32: upgrade taus88 generator to taus113 from errata paper
  random32: move rnd_state to linux/random.h
  random32: add prandom_reseed_late() and call when nonblocking pool becomes initialized
  random32: add periodic reseeding
  random32: fix off-by-one in seeding requirement
  PHY: Add RTL8201CP phy_driver to realtek
  xtsonic: add missing platform_set_drvdata() in xtsonic_probe()
  macmace: add missing platform_set_drvdata() in mace_probe()
  ethernet/arc/arc_emac: add missing platform_set_drvdata() in arc_emac_probe()
  ipv6: protect for_each_sk_fl_rcu in mem_check with rcu_read_lock_bh
  vlan: Implement vlan_dev_get_egress_qos_mask as an inline.
  ixgbe: add warning when max_vfs is out of range.
  igb: Update link modes display in ethtool
  netfilter: push reasm skb through instead of original frag skbs
  ip6_output: fragment outgoing reassembled skb properly
  MAINTAINERS: mv643xx_eth: take over maintainership from Lennart
  net_sched: tbf: support of 64bit rates
  ixgbe: deleting dfwd stations out of order can cause null ptr deref
  ixgbe: fix build err, num_rx_queues is only available with CONFIG_RPS
  ...
2013-11-13 17:40:34 +09:00
Roel Kluin 261adc9a60 jump_label: unlikely(x) > 0
if (unlikely(x) > 0) doesn't seem to help branch prediction

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-13 12:09:13 +09:00
Hannes Frederic Sowa c4b2c0c5f6 static_key: WARN on usage before jump_label_init was called
Usage of the static key primitives to toggle a branch must not be used
before jump_label_init() is called from init/main.c. jump_label_init
reorganizes and wires up the jump_entries so usage before that could
have unforeseen consequences.

Following primitives are now checked for correct use:
* static_key_slow_inc
* static_key_slow_dec
* static_key_slow_dec_deferred
* jump_label_rate_limit

The x86 architecture already checks this by testing if the default_nop
was already replaced with an optimal nop or with a branch instruction. It
will panic then. Other architectures don't check for this.

Because we need to relax this check for the x86 arch to allow code to
transition from default_nop to the enabled state and other architectures
did not check for this at all this patch introduces checking on the
static_key primitives in a non-arch dependent manner.

All checked functions are considered slow-path so the additional check
does no harm to performance.

The warnings are best observed with earlyprintk.

Based on a patch from Andi Kleen.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 19:45:35 -04:00
Andrew Jones 851cf6e7d6 jump_label: Split jumplabel ratelimit
Commit b202952075 ("perf, core: Rate limit
perf_sched_events jump_label patching") introduced rate limiting
for jump label disabling. The changes were made in the jump label code
in order to be more widely available and to keep things tidier. This is
all fine, except now jump_label.h includes linux/workqueue.h, which
makes it impossible to include jump_label.h from anything that
workqueue.h needs. For example, it's now impossible to include
jump_label.h from asm/spinlock.h, which is done in proposed
pv-ticketlock patches. This patch splits out the rate limiting related
changes from jump_label.h into a new file, jump_label_ratelimit.h, to
resolve the issue.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Link: http://lkml.kernel.org/r/1376058122-8248-10-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-08-09 07:53:54 -07:00
Jason Baron 47fbc518a4 jump label: Remove static_branch()
Remove the obsolete static_branch() interface, since the supported interface
is now static_key_false()/true() - which is used by all in-tree code.

See commit:

  c5905afb0e ("static keys: Introduce 'struct static_key', static_key_true()/false()
  and static_key_slow_[inc|dec]()").

Signed-off-by: Jason Baron <jbaron@redhat.com>
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/199332c47eef8005d5a5bf1018a80d25929a5746.1340909155.git.jbaron@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-07-06 10:53:49 +02:00
Jason Baron 8eedce9965 static keys: Inline the static_key_enabled() function
In the jump label enabled case, calling static_key_enabled()
results in a function call. The function returns the results of
a compare, so it really doesn't need the overhead of a full
function call. Let's make it 'static inline' for both the jump
label enabled and disabled cases.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Cc: a.p.zijlstra@chello.nl
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/201202281849.q1SIn1p2023270@int-mx10.intmail.prod.int.phx2.redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-28 20:01:08 +01:00
Ingo Molnar c5905afb0e static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()
So here's a boot tested patch on top of Jason's series that does
all the cleanups I talked about and turns jump labels into a
more intuitive to use facility. It should also address the
various misconceptions and confusions that surround jump labels.

Typical usage scenarios:

        #include <linux/static_key.h>

        struct static_key key = STATIC_KEY_INIT_TRUE;

        if (static_key_false(&key))
                do unlikely code
        else
                do likely code

Or:

        if (static_key_true(&key))
                do likely code
        else
                do unlikely code

The static key is modified via:

        static_key_slow_inc(&key);
        ...
        static_key_slow_dec(&key);

The 'slow' prefix makes it abundantly clear that this is an
expensive operation.

I've updated all in-kernel code to use this everywhere. Note
that I (intentionally) have not pushed through the rename
blindly through to the lowest levels: the actual jump-label
patching arch facility should be named like that, so we want to
decouple jump labels from the static-key facility a bit.

On non-jump-label enabled architectures static keys default to
likely()/unlikely() branches.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: a.p.zijlstra@chello.nl
Cc: mathieu.desnoyers@efficios.com
Cc: davem@davemloft.net
Cc: ddaney.cavm@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.hu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-24 10:05:59 +01:00
Peter Zijlstra efb3040d48 jump_label: Add some documentation
akpm figured we could do with a blub explaining what static_branch()
is and why it lives...

Grumpily-requested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-h02wu6kabpoojxf03wke704k@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-01-27 12:14:46 +01:00
Peter Zijlstra ac99b862fb jump_label: Provide jump_label_key initializers
Provide two initializers for jump_label_key that initialize it enabled
or disabled. Also modify all jump_label code to allow for jump_labels to be
initialized enabled.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/n/tip-p40e3yj21b68y03z1yv825e7@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-06 20:41:03 +01:00