Commit graph

42 commits

Author SHA1 Message Date
Kees Cook
54acd4397d rculist: Consolidate DEBUG_LIST for list_add_rcu()
This commit consolidates the debug checking for list_add_rcu() into the
new single __list_add_valid() debug function.  Notably, this commit fixes
the sanity check that was added in commit 17a801f4bf ("list_debug:
WARN for adding something already in the list"), which wasn't checking
RCU-protected lists.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
2016-10-31 13:01:57 -07:00
David S. Miller
1602f49b58 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts were two cases of simple overlapping changes,
nothing serious.

In the UDP case, we need to add a hlist_add_tail_rcu()
to linux/rculist.h, because we've moved UDP socket handling
away from using nulls lists.

Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-23 18:51:33 -04:00
Tom Herbert
ff3c44e675 rcu: Add list_next_or_null_rcu
This is a convenience function that returns the next entry in an RCU
list or NULL if at the end of the list.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-03-09 16:36:13 -05:00
Paul E. McKenney
648c630c64 Merge branches 'doc.2015.12.05a', 'exp.2015.12.07a', 'fixes.2015.12.07a', 'list.2015.12.04b' and 'torture.2015.12.05a' into HEAD
doc.2015.12.05a:  Documentation updates
exp.2015.12.07a:  Expedited grace-period updates
fixes.2015.12.07a:  Miscellaneous fixes
list.2015.12.04b:  Linked-list updates
torture.2015.12.05a:  Torture-test updates
2015-12-07 17:02:54 -08:00
Alexey Kardashevskiy
69b907297f list: Add lockless list traversal primitives
Although list_for_each_entry_rcu() can in theory be used anywhere
preemption is disabled, it can result in calls to lockdep, which cannot
be used in certain constrained execution environments, such as exception
handlers that do not map the entire kernel into their address spaces.
This commit therefore adds list_entry_lockless() and
list_for_each_entry_lockless(), which never invoke lockdep and can
therefore safely be used from these constrained environments, but only
as long as those environments are non-preemptible (or items are never
deleted from the list).

Use synchronize_sched(), call_rcu_sched(), or synchronize_sched_expedited()
in updates for the needed grace periods.  Of course, if items are never
deleted from the list, there is no need to wait for grace periods.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-07 17:01:33 -08:00
Petko Manolov
7d86dccf28 list: Introduces generic list_splice_tail_init_rcu()
The list_splice_init_rcu() can be used as a stack onto which full lists
are pushed, but queue-like behavior is now needed by some security
policies.  This requires a list_splice_tail_init_rcu().

This commit therefore supplies a list_splice_tail_init_rcu() by
pulling code common it and to list_splice_init_rcu() into a new
__list_splice_init_rcu() function.  This new function is based on the
existing list_splice_init_rcu() implementation.

Signed-off-by: Petko Manolov <petkan@mip-labs.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-04 12:34:32 -08:00
Patrick Marlier
8db70b132d rculist: Make list_entry_rcu() use lockless_dereference()
The current list_entry_rcu() implementation copies the pointer to a stack
variable, then invokes rcu_dereference_raw() on it.  This results in an
additional store-load pair.  Now, most compilers will emit normal store
and load instructions, which might seem to be of negligible overhead,
but this results in a load-hit-store situation that can cause surprisingly
long pipeline stalls, even on modern microprocessors.  The problem is
that it takes time for the store to get the store buffer updated, which
can delay the subsequent load, which immediately follows.

This commit therefore switches to the lockless_dereference() primitive,
which does not expect the __rcu annotations (that are anyway not present
in the list_head structure) and which, like rcu_dereference_raw(),
does not check for an enclosing RCU read-side critical section.
Most importantly, it does not copy the pointer, thus avoiding the
load-hit-store overhead.

Signed-off-by: Patrick Marlier <patrick.marlier@gmail.com>
[ paulmck: Switched to lockless_dereference() to suppress sparse warnings. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:16:18 -07:00
Ying Xue
f517700cce rculist: Fix another sparse warning
This fixes the following sparse warnings:

make C=1 CF=-D__CHECK_ENDIAN__ net/tipc/name_table.o
net/tipc/name_table.c:977:17: error: incompatible types in comparison expression (different address spaces)
net/tipc/name_table.c:977:17: error: incompatible types in comparison expression (different address spaces)

To silence these spare complaints, an RCU annotation should be added to
"next" pointer of hlist_node structure through hlist_next_rcu() macro
when iterating over a hlist with hlist_for_each_entry_from_rcu().

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-05-27 12:58:04 -07:00
Paul E. McKenney
7d0ae8086b rcu: Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE()
and WRITE_ONCE() APIs.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck:  Updated to include kernel/torture.c as suggested by Jason Low. ]
2015-05-27 12:56:15 -07:00
Ying Xue
f520c98e3e rculist: Fix sparse warning
This fixes the following sparse warnings:

make C=1 CF=-D__CHECK_ENDIAN__ net/ipv6/addrconf.o
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)

To silence these spare complaints, an RCU annotation should be added to
"next" pointer of hlist_node structure through hlist_next_rcu() macro
when iterating over a hlist with hlist_for_each_entry_continue_rcu_bh().

By the way, this commit also resolves the same error appearing in
hlist_for_each_entry_continue_rcu().

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-01-06 11:01:13 -08:00
Linus Torvalds
a7cb7bb664 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
Pull trivial tree update from Jiri Kosina:
 "Usual stuff: documentation updates, printk() fixes, etc"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (24 commits)
  intel_ips: fix a type in error message
  cpufreq: cpufreq-dt: Move newline to end of error message
  ps3rom: fix error return code
  treewide: fix typo in printk and Kconfig
  ARM: dts: bcm63138: change "interupts" to "interrupts"
  Replace mentions of "list_struct" to "list_head"
  kernel: trace: fix printk message
  scsi: mpt2sas: fix ioctl in comment
  zbud, zswap: change module author email
  clocksource: Fix 'clcoksource' typo in comment
  arm: fix wording of "Crotex" in CONFIG_ARCH_EXYNOS3 help
  gpio: msm-v1: make boolean argument more obvious
  usb: Fix typo in usb-serial-simple.c
  PCI: Fix comment typo 'COMFIG_PM_OPS'
  powerpc: Fix comment typo 'CONIFG_8xx'
  powerpc: Fix comment typos 'CONFiG_ALTIVEC'
  clk: st: Spelling s/stucture/structure/
  isci: Spelling s/stucture/structure/
  usb: gadget: zero: Spelling s/infrastucture/infrastructure/
  treewide: Fix company name in module descriptions
  ...
2014-12-12 10:08:06 -08:00
Ying Xue
97ede29e80 tipc: convert name table read-write lock to RCU
Convert tipc name table read-write lock to RCU. After this change,
a new spin lock is used to protect name table on write side while
RCU is applied on read side.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Tested-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-08 20:39:57 -05:00
Andrey Utkin
3943f42c11 Replace mentions of "list_struct" to "list_head"
There's no such thing as "list_struct".

Signed-off-by: Andrey Utkin <andrey.krieger.utkin@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2014-11-20 14:45:15 +01:00
Ken Helias
1d023284c3 list: fix order of arguments for hlist_add_after(_rcu)
All other add functions for lists have the new item as first argument
and the position where it is added as second argument.  This was changed
for no good reason in this function and makes using it unnecessary
confusing.

The name was changed to hlist_add_behind() to cause unconverted code to
generate a compile error instead of using the wrong parameter order.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Ken Helias <kenhelias@firemail.de>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>	[intel driver bits]
Cc: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-06 18:01:24 -07:00
Joe Perches
0adab9b9aa rcu: Indentation and spacing fixes.
This commit outdents expression-statement macros, thus repairing a few
line-length complaints.  Also fix some spacing errors called out by
checkpatch.pl.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-17 15:01:52 -08:00
Teodora Baluta
584dc4ce55 rcu: Remove "extern" from function declarations in include/linux/*rcu*.h
Function prototypes don't need to have the "extern" keyword since this
is the default behavior. Its explicit use is redundant.  This commit
therefore removes them.

Signed-off-by: Teodora Baluta <teobaluta@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-12 12:34:16 -08:00
Paul E. McKenney
2a855b644c rcu: Make list_splice_init_rcu() account for RCU readers
The list_splice_init_rcu() function allows a list visible to RCU readers
to be spliced into another list visible to RCU readers.  This is OK,
except for the use of INIT_LIST_HEAD(), which does pointer updates
without doing anything to make those updates safe for concurrent readers.

Of course, most of the time INIT_LIST_HEAD() is being used in reader-free
contexts, such as initialization or cleanup, so it is OK for it to update
pointers in an unsafe-for-RCU-readers manner.  This commit therefore
creates an INIT_LIST_HEAD_RCU() that uses ACCESS_ONCE() to make the updates
reader-safe.  The reason that we can use ACCESS_ONCE() instead of the more
typical rcu_assign_pointer() is that list_splice_init_rcu() is updating the
pointers to reference something that is already visible to readers, so
that there is no problem with pre-initialized values.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-09-23 09:13:49 -07:00
Tejun Heo
c34ac00cae rculist: list_first_or_null_rcu() should use list_entry_rcu()
list_first_or_null() should test whether the list is empty and return
pointer to the first entry if not in a RCU safe manner.  It's broken
in several ways.

* It compares __kernel @__ptr with __rcu @__next triggering the
  following sparse warning.

  net/core/dev.c:4331:17: error: incompatible types in comparison expression (different address spaces)

* It doesn't perform rcu_dereference*() and computes the entry address
  using container_of() directly from the __rcu pointer which is
  inconsitent with other rculist interface.  As a result, all three
  in-kernel users - net/core/dev.c, macvlan, cgroup - are buggy.  They
  dereference the pointer w/o going through read barrier.

* While ->next dereference passes through list_next_rcu(), the
  compiler is still free to fetch ->next more than once and thus
  nullify the "__ptr != __next" condition check.

Fix it by making list_first_or_null_rcu() dereference ->next directly
using ACCESS_ONCE() and then use list_entry_rcu() on it like other
rculist accessors.

v2: Paul pointed out that the compiler may fetch the pointer more than
    once nullifying the condition check.  ACCESS_ONCE() added on
    ->next dereference.

v3: Restored () around macro param which was accidentally removed.
    Spotted by Paul.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: stable@vger.kernel.org
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2013-08-18 17:40:16 -07:00
Steven Rostedt
12bcbe66d7 rcu: Add _notrace variation of rcu_dereference_raw() and hlist_for_each_entry_rcu()
As rcu_dereference_raw() under RCU debug config options can add quite a
bit of checks, and that tracing uses rcu_dereference_raw(), these checks
happen with the function tracer. The function tracer also happens to trace
these debug checks too. This added overhead can livelock the system.

Add a new interface to RCU for both rcu_dereference_raw_notrace() as well
as hlist_for_each_entry_rcu_notrace() as the hlist iterator uses the
rcu_dereference_raw() as well, and is used a bit with the function tracer.

Link: http://lkml.kernel.org/r/20130528184209.304356745@goodmis.org

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-05-28 22:47:13 -04:00
Sasha Levin
b67bfe0d42 hlist: drop the node parameter from iterators
I'm not sure why, but the hlist for each entry iterators were conceived

        list_for_each_entry(pos, head, member)

The hlist ones were greedy and wanted an extra parameter:

        hlist_for_each_entry(tpos, pos, head, member)

Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.

Besides the semantic patch, there was some manual work required:

 - Fix up the actual hlist iterators in linux/list.h
 - Fix up the declaration of other iterators based on the hlist ones.
 - A very small amount of places were using the 'node' parameter, this
 was modified to use 'obj->member' instead.
 - Coccinelle didn't handle the hlist_for_each_entry_safe iterator
 properly, so those had to be fixed up manually.

The semantic patch which is mostly the work of Peter Senna Tschudin is here:

@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;

type T;
expression a,c,d,e;
identifier b;
statement S;
@@

-T b;
    <+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
    ...+>

[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 19:10:24 -08:00
Paul E. McKenney
bb08f76d84 rcu: Remove list_for_each_continue_rcu()
The list_for_each_continue_rcu() macro is no longer used, so this commit
removes it.  The list_for_each_entry_continue_rcu() macro should be
used instead.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-13 14:08:21 -08:00
Michel Machado
f88022a4f6 rcu: Replace list_first_entry_rcu() with list_first_or_null_rcu()
The list_first_entry_rcu() macro is inherently unsafe because it cannot
be applied to an empty list.  But because RCU readers do not exclude
updaters, a list might become empty between the time that list_empty()
claimed it was non-empty and the time that list_first_entry_rcu() is
invoked.  Therefore, the list_empty() test cannot be separated from the
list_first_entry_rcu() call.  This commit therefore combines these to
macros to create a new list_first_or_null_rcu() macro that replaces
the old (and unsafe) list_first_entry_rcu() macro.

This patch incorporates Paul's review comments on the previous version of
this patch available here:

https://lkml.org/lkml/2012/4/2/536

This patch cannot break any upstream code because list_first_entry_rcu()
is not being used anywhere in the kernel (tested with grep(1)), and any
external code using it is probably broken as a result of using it.

Signed-off-by: Michel Machado <michel@digirati.com.br>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-04-24 20:54:49 -07:00
Dave Jones
559f9badd1 rcu: List-debug variants of rcu list routines.
* Make __list_add_rcu check the next->prev and prev->next pointers
  just like __list_add does.
* Make list_del_rcu use __list_del_entry, which does the same checking
  at deletion time.

Has been running for a week here without anything being tripped up,
but it seems worth adding for completeness just in case something
ever does corrupt those lists.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-04-24 20:54:49 -07:00
Jan H. Schönherr
7f70893173 rcu: Fix wrong check in list_splice_init_rcu()
If the list to be spliced is empty, then list_splice_init_rcu() has
nothing to do.  Unfortunately, list_splice_init_rcu() does not check
the list to be spliced; it instead checks the list to be spliced into.
This results in memory leaks given current usage.  This commit
therefore fixes the empty-list check.

Signed-off-by: Jan H. Schönherr <schnhrr@cs.tu-berlin.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-07-20 14:10:20 -07:00
Linus Torvalds
e66eed651f list: remove prefetching from regular list iterators
This is removes the use of software prefetching from the regular list
iterators.  We don't want it.  If you do want to prefetch in some
iterator of yours, go right ahead.  Just don't expect the iterator to do
it, since normally the downsides are bigger than the upsides.

It also replaces <linux/prefetch.h> with <linux/const.h>, because the
use of LIST_POISON ends up needing it.  <linux/poison.h> is sadly not
self-contained, and including prefetch.h just happened to hide that.

Suggested by David Miller (networking has a lot of regular lists that
are often empty or a single entry, and prefetching is not going to do
anything but add useless instructions).

Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-19 14:15:29 -07:00
Linus Torvalds
75d65a425c hlist: remove software prefetching in hlist iterators
They not only increase the code footprint, they actually make things
slower rather than faster.  On internationally acclaimed benchmarks
("make -j16" on an already fully built kernel source tree) the hlist
prefetching slows down the build by up to 1%.

(Almost all of it comes from hlist_for_each_entry_rcu() as used by
avc_has_perm_noaudit(), which is very hot due to all the pathname
lookups to see if there is anything to do).

The cause seems to be two-fold:

 - on at least some Intel cores, prefetch(NULL) ends up with some
   microarchitectural stall due to the TLB miss that it incurs.  The
   hlist case triggers this very commonly, since the NULL pointer is the
   last entry in the list.

 - the prefetch appears to cause more D$ activity, probably because it
   prefetches hash list entries that are never actually used (because we
   ended the search early due to a hit).

Regardless, the numbers clearly say that the implicit prefetching is
simply a bad idea.  If some _particular_ user of the hlist iterators
wants to prefetch the next list entry, they can do so themselves
explicitly, rather than depend on all list iterators doing so
implicitly.

Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-19 13:50:07 -07:00
Paul E. McKenney
3c2dcf2aed rcu: remove unused __list_for_each_rcu() macro
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2010-12-17 12:34:59 -08:00
Mariusz Kozlowski
8a9c1cee26 rculist: fix borked __list_for_each_rcu() macro
This restores parentheses blance.

Signed-off-by: Mariusz Kozlowski <mk@lab.zgora.pl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2010-12-17 12:34:58 -08:00
Paul E. McKenney
65e6bf484c rcu: add comment stating that list_empty() applies to RCU-protected lists
Because list_empty() does not dereference any RCU-protected pointers, and
further does not pass such pointers to the caller (so that the caller
does not dereference them either), it is safe to use list_empty() on
RCU-protected lists.  There is no need for a list_empty_rcu().  This
commit adds a comment stating this explicitly.

Requested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2010-08-20 09:00:18 -07:00
Arnd Bergmann
67bdbffd69 rculist: avoid __rcu annotations
This avoids warnings from missing __rcu annotations
in the rculist implementation, making it possible to
use the same lists in both RCU and non-RCU cases.

We can add rculist annotations later, together with
lockdep support for rculist, which is missing as well,
but that may involve changing all the users.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2010-08-19 17:18:00 -07:00
Eric Dumazet
4f70ecca9c net: rcu fixes
Add hlist_for_each_entry_rcu_bh() and
hlist_for_each_entry_continue_rcu_bh() macros, and use them in
ipv6_get_ifaddr(), if6_get_first() and if6_get_next() to fix lockdeps
warnings.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-05-03 15:53:54 -07:00
stephen hemminger
5c578aedcb IPv6: convert addrconf hash list to RCU
Convert from reader/writer lock to RCU and spinlock for addrconf
hash list.

Adds an additional helper macro for hlist_for_each_entry_continue_rcu
to handle the continue case.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-03-20 15:44:35 -07:00
David S. Miller
47871889c6 Merge branch 'master' of /home/davem/src/GIT/linux-2.6/
Conflicts:
	drivers/firmware/iscsi_ibft.c
2010-02-28 19:23:06 -08:00
Paul E. McKenney
3120438ad6 rcu: Disable lockdep checking in RCU list-traversal primitives
The theory is that use of bare rcu_dereference() is more prone
to error than use of the RCU list-traversal primitives.
Therefore, disable lockdep RCU read-side critical-section
checking in these primitives for the time being.  Once all of
the rcu_dereference() uses have been dealt with, it may be time
to re-enable lockdep checking for the RCU list-traversal
primitives.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-4-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-25 09:41:02 +01:00
stephen hemminger
1cc523271e seq_file: add RCU versions of new hlist/list iterators (v3)
Many usages of seq_file use RCU protected lists, so non RCU
iterators will not work safely.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-02-22 15:45:54 -08:00
stephen hemminger
254245d233 netdev: add netdev_continue_rcu
This adds an RCU macro for continuing search, useful for some
network devices like vlan.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-11-10 22:26:29 -08:00
Jiri Pirko
72c6a9870f rculist.h: introduce list_entry_rcu() and list_first_entry_rcu()
I've run into the situation where I need to use list_first_entry with
rcu-guarded list. This patch introduces this.

Also simplify list_for_each_entry_rcu() to use new list_entry_rcu()
instead of list_entry().

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: dipankar@in.ibm.com
LKML-Reference: <20090414153356.GC3999@psychotron.englab.brq.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-14 18:41:15 +02:00
Paul E. McKenney
34d7c2b38d rcu: remove list_for_each_rcu()
All of the in-tree uses of list_for_each_rcu() have been converted to
list_for_each_entry_rcu(), so list_for_each_rcu() can now be removed.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-15 17:03:06 +02:00
Andrea Arcangeli
6beeac76f5 mmu-notifiers: add list_del_init_rcu()
Introduce list_del_init_rcu() and document it.

Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Kanoj Sarcar <kanojsarcar@yahoo.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Steve Wise <swise@opengridcomputing.com>
Cc: Avi Kivity <avi@qumranet.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Cc: Chris Wright <chrisw@redhat.com>
Cc: Marcelo Tosatti <marcelo@kvack.org>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Izik Eidus <izike@qumranet.com>
Cc: Anthony Liguori <aliguori@us.ibm.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>
2008-07-28 16:30:20 -07:00
Paul E. McKenney
78b0e0e9b2 RCU, rculist.h: fix list iterators
RCU list iterators: should prefetch ever be optimised out with no
side-effects, the current version will lose the barrier completely.

Pointed-out-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-19 10:03:39 +02:00
Franck Bui-Huu
10aa9d2cf9 rculist.h: use the rcu API
Make almost all list mutation primitives use rcu_assign_pointer().

The main point of this being readability improvement.

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Josh Triplett <josh@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-19 10:03:38 +02:00
Franck Bui-Huu
82524746c2 rcu: split list.h and move rcu-protected lists into rculist.h
Move rcu-protected lists from list.h into a new header file rculist.h.

This is done because list are a very used primitive structure all over the
kernel and it's currently impossible to include other header files in this
list.h without creating some circular dependencies.

For example, list.h implements rcu-protected list and uses rcu_dereference()
without including rcupdate.h.  It actually compiles because users of
rcu_dereference() are macros.  Others RCU functions could be used too but
aren't probably because of this.

Therefore this patch creates rculist.h which includes rcupdates without to
many changes/troubles.

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Josh Triplett <josh@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-19 10:01:37 +02:00