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rwsem: Implement down_read_interruptible 

[ Upstream commit 31784cff7e ]

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>
5.4-rM2-2.2.x-imx-squashed
Eric W. Biederman 2020-12-03 14:11:13 -06:00 committed by Greg Kroah-Hartman
parent 1b75a263fb
commit d390fc97df
2 changed files with 27 additions and 0 deletions
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1
include/linux/rwsem.h
View File

@ -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);
/*

26
kernel/locking/rwsem.c
View File

@ -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();