[patch V3 44/64] locking/ww_mutex: Abstract mutex accessors

Thomas Gleixner
2021-08-05T15:44:38Z

From: Peter Zijlstra <peterz@infradead.org>

Move the mutex related access from various ww_mutex functions into helper
functions so they can be substituted for rtmutex based ww_mutex later.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
kernel/locking/ww_mutex.h | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
---
--- a/kernel/locking/ww_mutex.h
+++ b/kernel/locking/ww_mutex.h
@@ -53,6 +53,18 @@ static inline void
__mutex_add_waiter(lock, waiter, p);
}

+static inline struct task_struct *
+__ww_mutex_owner(struct mutex *lock)
+{
+ return __mutex_owner(lock);
+}
+
+static inline bool
+__ww_mutex_has_waiters(struct mutex *lock)
+{
+ return atomic_long_read(&lock->owner) & MUTEX_FLAG_WAITERS;
+}
+
/*
* Wait-Die:
* The newer transactions are killed when:
@@ -157,7 +169,7 @@ static bool __ww_mutex_wound(struct mute
struct ww_acquire_ctx *ww_ctx,
struct ww_acquire_ctx *hold_ctx)
{
- struct task_struct *owner = __mutex_owner(lock);
+ struct task_struct *owner = __ww_mutex_owner(lock);

lockdep_assert_held(&lock->wait_lock);

@@ -253,7 +265,7 @@ ww_mutex_set_context_fastpath(struct ww_
* __ww_mutex_add_waiter() and makes sure we either observe ww->ctx
* and/or !empty list.
*/
- if (likely(!(atomic_long_read(&lock->base.owner) & MUTEX_FLAG_WAITERS)))
+ if (likely(!__ww_mutex_has_waiters(&lock->base)))
return;

/*