diff options
| author |   Jason Low <jason.low2@hp.com> | 2015-04-08 12:39:19 -0700 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2015-04-09 08:10:23 +0200 |
| commit | 01ac33c1f907b366dcc50551316b372f1519cca9 (patch) | |
| tree | 3acec01dacf54ca648dda938b21fe5a0626f9e5b /kernel | |
| parent | locking: Remove atomicy checks from {READ,WRITE}_ONCE (diff) | |
| download | linux-dev-01ac33c1f907b366dcc50551316b372f1519cca9.tar.xz linux-dev-01ac33c1f907b366dcc50551316b372f1519cca9.zip | |
locking/mutex: Further simplify mutex_spin_on_owner()
Similar to what Linus suggested for rwsem_spin_on_owner(), in
mutex_spin_on_owner() instead of having while (true) and
breaking out of the spin loop on lock->owner != owner, we can
have the loop directly check for while (lock->owner == owner) to
improve the readability of the code.
It also shrinks the code a bit:
text data bss dec hex filename
3721 0 0 3721 e89 mutex.o.before
3705 0 0 3705 e79 mutex.o.after
Signed-off-by: Jason Low <jason.low2@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Link: http://lkml.kernel.org/r/1428521960-5268-2-git-send-email-jason.low2@hp.com
[ Added code generation info. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/locking/mutex.c | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 16b2d3cc88b0..4cccea6b8934 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -224,20 +224,14 @@ ww_mutex_set_context_slowpath(struct ww_mutex *lock, static noinline bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) { - bool ret; + bool ret = true; rcu_read_lock(); - while (true) { - /* Return success when the lock owner changed */ - if (lock->owner != owner) { - ret = true; - break; - } - + while (lock->owner == owner) { /* * Ensure we emit the owner->on_cpu, dereference _after_ - * checking lock->owner still matches owner, if that fails, - * owner might point to free()d memory, if it still matches, + * checking lock->owner still matches owner. If that fails, + * owner might point to freed memory. If it still matches, * the rcu_read_lock() ensures the memory stays valid. */ barrier(); |