Commit graph

24 commits

Author SHA1 Message Date
Andi Kleen
ec48c940da kref: remove WARN_ON for NULL release functions
The kref functions check for NULL release functions.  This WARN_ON seems
rather pointless.  We will eventually release and then just crash
nicely.  It is also somewhat expensive because these functions are
inlined in a lot of places.  Removing the WARN_ONs saves around 2.3k in
this kernel (likely more in others with more drivers)

     text    data     bss     dec     hex filename
  9083992 5367600 11116544        25568136        1862388 vmlinux-before-load-avg
  9070166 5367600 11116544        25554310        185ed86 vmlinux-load-avg

Link: http://lkml.kernel.org/r/20170315021431.13107-5-andi@firstfloor.org
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-08 17:15:14 -07:00
Peter Zijlstra
10383aea2f kref: Implement 'struct kref' using refcount_t
Use the refcount_t 'atomic' type to implement 'struct kref', this makes kref
more robust by bringing saturation semantics.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-02-10 09:04:19 +01:00
Peter Zijlstra
0a13cd1a05 locking/atomic, kref: Implement kref_put_lock()
Because home-rolling your own is _awesome_, stop doing it. Provide
kref_put_lock(), just like kref_put_mutex() but for a spinlock.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.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>
2017-01-18 10:03:29 +01:00
Peter Zijlstra
bdfafc4ffd locking/atomic, kref: Kill kref_sub()
By general sentiment kref_sub() is a bad interface, make it go away.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.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>
2017-01-14 11:37:19 +01:00
Peter Zijlstra
2c935bc572 locking/atomic, kref: Add kref_read()
Since we need to change the implementation, stop exposing internals.

Provide kref_read() to read the current reference count; typically
used for debug messages.

Kills two anti-patterns:

	atomic_read(&kref->refcount)
	kref->refcount.counter

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.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>
2017-01-14 11:37:18 +01:00
Peter Zijlstra
1e24edca05 locking/atomic, kref: Add KREF_INIT()
Since we need to change the implementation, stop exposing internals.

Provide KREF_INIT() to allow static initialization of struct kref.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.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>
2017-01-14 11:37:18 +01:00
Bart Van Assche
3a66d7dca1 kref: Remove kref_put_spinlock_irqsave()
The last user is gone. Hence remove this function.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Joern Engel <joern@logfs.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2015-11-28 19:33:29 -08:00
Linus Torvalds
5c64e3a45d Merge branch 'queue' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending
Pull target fixes from Nicholas Bellinger:
 "A handful of fixes + minor changes this time around, along with one
  important >= v3.9 regression fix for IBLOCK backends.  The highlights
  include:

   - Use FD_MAX_SECTORS in FILEIO for block_device as
     well as files (agrover)

   - Fix processing of out-of-order CmdSNs with
     iSBD driver (shlomo)

   - Close long-standing target_put_sess_cmd() vs.
     core_tmr_abort_task() race with the addition of
     kref_put_spinlock_irqsave() (joern + greg-kh)

   - Fix IBLOCK WCE=1 + DPOFUA=1 backend WRITE
     regression in >= v3.9 (nab + bootc)

  Note these four patches are CC'ed to stable.

  Also, there is still some work left to be done on the active I/O
  shutdown path in target_wait_for_sess_cmds() used by tcm_qla2xxx +
  ib_isert fabrics that is still being discussed on the list, and will
  hopefully be resolved soon."

* 'queue' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
  target: close target_put_sess_cmd() vs. core_tmr_abort_task() race
  target: removed unused transport_state flag
  target/iblock: Fix WCE=1 + DPOFUA=1 backend WRITE regression
  MAINTAINERS: Update target git tree URL
  iscsi-target: Fix typos in RDMAEXTENSIONS macro usage
  target/rd: Add ramdisk bit for NULLIO operation
  iscsi-target: Fix processing of OOO commands
  iscsi-target: Make buf param of iscsit_do_crypto_hash_buf() const void *
  iscsi-target: Fix NULL pointer dereference in iscsit_send_reject
  target: Have dev/enable show if TCM device is configured
  target: Use FD_MAX_SECTORS/FD_BLOCKSIZE for blockdevs using fileio
  target: Remove unused struct members in se_dev_entry
2013-05-16 07:55:07 -07:00
Joern Engel
ccf5ae83a6 target: close target_put_sess_cmd() vs. core_tmr_abort_task() race
It is possible for one thread to to take se_sess->sess_cmd_lock in
core_tmr_abort_task() before taking a reference count on
se_cmd->cmd_kref, while another thread in target_put_sess_cmd() drops
se_cmd->cmd_kref before taking se_sess->sess_cmd_lock.

This introduces kref_put_spinlock_irqsave() and uses it in
target_put_sess_cmd() to close the race window.

Signed-off-by: Joern Engel <joern@logfs.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2013-05-15 01:47:35 -07:00
Anatol Pomozov
2d864e4171 kref: minor cleanup
- make warning smp-safe
 - result of atomic _unless_zero functions should be checked by caller
   to avoid use-after-free error
 - trivial whitespace fix.

Link: https://lkml.org/lkml/2013/4/12/391

Tested: compile x86, boot machine and run xfstests
Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
[ Removed line-break, changed to use WARN_ON_ONCE()  - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-07 16:09:00 -07:00
Thomas Hellstrom
4b20db3de8 kref: Implement kref_get_unless_zero v3
This function is intended to simplify locking around refcounting for
objects that can be looked up from a lookup structure, and which are
removed from that lookup structure in the object destructor.
Operations on such objects require at least a read lock around
lookup + kref_get, and a write lock around kref_put + remove from lookup
structure. Furthermore, RCU implementations become extremely tricky.
With a lookup followed by a kref_get_unless_zero *with return value check*
locking in the kref_put path can be deferred to the actual removal from
the lookup structure and RCU lookups become trivial.

v2: Formatting fixes.
v3: Invert the return value.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-11-20 16:15:02 +10:00
Al Viro
8ad5db8a8d introduce kref_put_mutex()
equivalent of
	mutex_lock(mutex);
	if (!kref_put(kref, release))
		mutex_unlock(mutex);

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-22 10:24:41 -04:00
James Bottomley
67175b855b Fix compile breakage with kref.h
This set of build failures just started appearing on parisc:

  In file included from drivers/input/serio/serio_raw.c:12:
  include/linux/kref.h: In function 'kref_get':
  include/linux/kref.h:40: error: 'TAINT_WARN' undeclared (first use in this function)
  include/linux/kref.h:40: error: (Each undeclared identifier is reported only once
  include/linux/kref.h:40: error: for each function it appears in.)
  include/linux/kref.h: In function 'kref_sub':
  include/linux/kref.h:65: error: 'TAINT_WARN' undeclared (first use in this function)

It happens because TAINT_WARN is defined in kernel.h and this particular
compile doesn't seem to include it (no idea why it's just manifesting ..
probably some #include file untangling exposed it).

Fix by adding

  #include <linux/kernel.h>

to linux/kref.h

Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-17 15:40:51 -08:00
Greg Kroah-Hartman
6261ddee70 kref: fix up the kfree build problems
It turns out that some memory allocators use kobjects, which use krefs,
and kref.h was wanting to figure out the address of kfree(), which ended
up in a loop.

kfree was only being needed for a warning to tell the caller that they
were doing something stupid.  Now we just move that warning into the
comments for the functions, which results in a bit more fun as everyone
enjoys digging for people to mock at times of boredom.

So, remove the dependancy of slab.h on kref.h, and fix up the other
include file as well (we really only need bug.h and atomic.h, not
types.h).

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-14 11:19:07 -08:00
Peter Zijlstra
3c8ed88974 kref: Remove the memory barriers
Commit 1b0b3b9980 ("kref: fix CPU ordering with respect to krefs")
wrongly adds memory barriers to kref.

It states:

  some atomic operations are only atomic, not ordered. Thus a CPU is allowed
  to reorder memory references to an object to before the reference is
  obtained. This fixes it.

While true, it fails to show why this is a problem. I say it is not a
problem because if there is a race with kref_put() such that we could
end up referencing a free'd object without this memory barrier, we
would still have that race with the memory barrier.

The kref_put() in question could complete (and free the object) before
the atomic_inc() and we'd still be up shit creek.

The kref_init() case is even worse, if your object is published at this
time you're so wrong the memory barrier won't make a difference what
so ever. If its not published, the act of publishing should include
the needed barriers/locks to make sure all writes prior to the act of
publishing are complete such that others will only observe a complete
object.

Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-13 09:11:19 -08:00
Peter Zijlstra
47dbd7d90a kref: Implement kref_put in terms of kref_sub
Less lines of code is better.

Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-13 08:41:43 -08:00
Peter Zijlstra
4af679cd7c kref: Inline all functions
These are tiny functions, there's no point in having them out-of-line.

Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-8eccvi2ur2fzgi00xdjlbf5z@git.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-13 08:18:25 -08:00
Thomas Hellstrom
ecf7ace9a8 kref: Add a kref_sub function
Makes it possible to optimize batched multiple unrefs.
Initial user will be drivers/gpu/ttm which accumulates unrefs to be
processed outside of atomic code.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-11-22 13:25:13 +10:00
NeilBrown
db1afffab0 kref: remove kref_set
Of the three uses of kref_set in the kernel:

 One really should be kref_put as the code is letting go of a
    reference,
 Two really should be kref_init because the kref is being
    initialised.

This suggests that making kref_set available encourages bad code.
So fix the three uses and remove kref_set completely.

Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-05-21 09:37:29 -07:00
Robert P. J. Day
932fb06b08 kobj: kref.h incorrectly describes itself as kref.c.
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-03-15 15:35:35 +01:00
Alexey Dobriyan
1d1764c398 headers: kref.h redux
* remove asm/atomic.h inclusion from kref.h -- not needed, linux/types.h
  is enough for atomic_t
* remove linux/kref.h inclusion from files which do not need it.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-26 10:17:19 -07:00
Robert P. J. Day
735643ee6c Remove "#ifdef __KERNEL__" checks from unexported headers
Remove the "#ifdef __KERNEL__" tests from unexported header files in
linux/include whose entire contents are wrapped in that preprocessor
test.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 08:29:54 -07:00
Evgeniy Polyakov
41ca28ab2a kref: add kref_set()
This adds kref_set() to the kref api for future use by people who really
know what they are doing with krefs...

From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24 20:40:05 -08:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00