From: Eric W. Biederman ebiederm@xmission.com
[ Upstream commit 31784cff7ee073b34d6eddabb95e3be2880a425c ]
In preparation for converting exec_update_mutex to a rwsem so that multiple readers can execute in parallel and not deadlock, add down_read_interruptible. This is needed for perf_event_open to be converted (with no semantic changes) from working on a mutex to wroking on a rwsem.
Signed-off-by: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/87k0tybqfy.fsf@x220.int.ebiederm.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/rwsem.h | 1 + kernel/locking/rwsem.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index c91ac00d1ff8c..8a3606372abc8 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -125,6 +125,7 @@ static inline int rwsem_is_contended(struct rw_semaphore *sem) * lock for reading */ extern void down_read(struct rw_semaphore *sem); +extern int __must_check down_read_interruptible(struct rw_semaphore *sem); extern int __must_check down_read_killable(struct rw_semaphore *sem);
/* diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 2ce13f9585779..a5eb87f2c5816 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -1348,6 +1348,18 @@ inline void __down_read(struct rw_semaphore *sem) } }
+static inline int __down_read_interruptible(struct rw_semaphore *sem) +{ + if (!rwsem_read_trylock(sem)) { + if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_INTERRUPTIBLE))) + return -EINTR; + DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem); + } else { + rwsem_set_reader_owned(sem); + } + return 0; +} + static inline int __down_read_killable(struct rw_semaphore *sem) { if (!rwsem_read_trylock(sem)) { @@ -1498,6 +1510,20 @@ void __sched down_read(struct rw_semaphore *sem) } EXPORT_SYMBOL(down_read);
+int __sched down_read_interruptible(struct rw_semaphore *sem) +{ + might_sleep(); + rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); + + if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_interruptible)) { + rwsem_release(&sem->dep_map, _RET_IP_); + return -EINTR; + } + + return 0; +} +EXPORT_SYMBOL(down_read_interruptible); + int __sched down_read_killable(struct rw_semaphore *sem) { might_sleep();