From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Waiman Long To: Ingo Molnar , Peter Zijlstra , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Davidlohr Bueso , "Theodore Y. Ts'o" , Oleg Nesterov , Amir Goldstein , Jan Kara , Waiman Long Subject: [RFC PATCH v2 2/2] locking/percpu-rwsem: Mark rwsem as non-spinnable in percpu_rwsem_release() Date: Mon, 14 May 2018 15:31:07 -0400 Message-Id: <1526326267-22501-3-git-send-email-longman@redhat.com> In-Reply-To: <1526326267-22501-1-git-send-email-longman@redhat.com> References: <1526326267-22501-1-git-send-email-longman@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: The percpu_rwsem_release() is called when the ownership of the embedded rwsem is to be transferred to another task. The new owner, however, may take a while to get the ownership of the lock via percpu_rwsem_acquire(). During that period, the rwsem is now marked as writer-owned with no optimistic spinning. Signed-off-by: Waiman Long --- include/linux/percpu-rwsem.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index b1f37a8..dd37102 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -131,16 +131,16 @@ static inline void percpu_rwsem_release(struct percpu_rw_semaphore *sem, bool read, unsigned long ip) { lock_release(&sem->rw_sem.dep_map, 1, ip); -#ifdef CONFIG_RWSEM_SPIN_ON_OWNER if (!read) - sem->rw_sem.owner = NULL; -#endif + rwsem_set_writer_owned_nospin(&sem->rw_sem); } static inline void percpu_rwsem_acquire(struct percpu_rw_semaphore *sem, bool read, unsigned long ip) { lock_acquire(&sem->rw_sem.dep_map, 0, 1, read, 1, NULL, ip); + if (!read) + rwsem_set_writer_owned(&sem->rw_sem, current); } #endif -- 1.8.3.1