Commit-ID: 01ac33c1f907b366dcc50551316b372f1519cca9 Gitweb: http://git.kernel.org/tip/01ac33c1f907b366dcc50551316b372f1519cca9 Author: Jason Low <[email protected]> AuthorDate: Wed, 8 Apr 2015 12:39:19 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 9 Apr 2015 08:10:23 +0200
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 <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Aswin Chandramouleeswaran <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Tim Chen <[email protected]> Link: http://lkml.kernel.org/r/[email protected] [ Added code generation info. ] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/locking/mutex.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 16b2d3c..4cccea6 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(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
