Messages in this thread Patch in this message | | | Subject | [PATCH] locking/mutex: Refactor mutex_spin_on_owner() | From | Jason Low <> | Date | Mon, 09 Mar 2015 13:14:54 -0700 |
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This patch applies on top of tip.
------------------------------------------------------------------- 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). This improves the readability of the code.
Signed-off-by: Jason Low <jason.low2@hp.com> --- kernel/locking/mutex.c | 17 +++++------------ 1 files changed, 5 insertions(+), 12 deletions(-)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 16b2d3c..1c3b7c5 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -224,16 +224,8 @@ 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; - 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, @@ -242,16 +234,17 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) */ barrier(); + /* Stop spinning when need_resched or owner is not running. */ if (!owner->on_cpu || need_resched()) { - ret = false; - break; + rcu_read_unlock(); + return false; } cpu_relax_lowlatency(); } rcu_read_unlock(); - return ret; + return true; } /* -- 1.7.2.5
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