diff options
| -rw-r--r-- | kernel/locking/mutex.c | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 38d173ce5762..92162391d477 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -378,6 +378,28 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner, struct mutex_waiter *waiter) { bool ret = true; + struct ww_acquire_ctx *owner_ww_ctx = NULL; + + if (use_ww_ctx && ww_ctx && ww_ctx->acquired > 0) { + struct ww_mutex *ww; + unsigned long flags; + + ww = container_of(lock, struct ww_mutex, base); + + /* + * Check the stamp of the current owner once. This allows us + * to spin optimistically in the case where the current owner + * has a higher stamp than us. + */ + spin_lock_mutex(&lock->wait_lock, flags); + owner_ww_ctx = ww->ctx; + if (owner_ww_ctx && + __ww_mutex_stamp_after(ww_ctx, owner_ww_ctx)) { + spin_unlock_mutex(&lock->wait_lock, flags); + return false; + } + spin_unlock_mutex(&lock->wait_lock, flags); + } rcu_read_lock(); while (__mutex_owner(lock) == owner) { @@ -414,9 +436,16 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner, * Check this in every inner iteration because we may * be racing against another thread's ww_mutex_lock. */ - if (ww_ctx->acquired > 0 && READ_ONCE(ww->ctx)) { - ret = false; - break; + if (ww_ctx->acquired > 0) { + struct ww_acquire_ctx *current_ctx; + + current_ctx = READ_ONCE(ww->ctx); + + if (current_ctx && + current_ctx != owner_ww_ctx) { + ret = false; + break; + } } /* |