Messages in this thread | | | Subject | Re: [PATCH 2/3] rwsem: Implement down_read_interruptible | From | Waiman Long <> | Date | Thu, 3 Dec 2020 20:59:13 -0500 |
| |
On 12/3/20 3:11 PM, Eric W. Biederman wrote: > 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. > > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Will Deacon <will@kernel.org> > Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> > --- > 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 13021b08b2ed..4c715be48717 100644 > --- a/include/linux/rwsem.h > +++ b/include/linux/rwsem.h > @@ -123,6 +123,7 @@ 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 54d11cb97551..a163542d178e 100644 > --- a/kernel/locking/rwsem.c > +++ b/kernel/locking/rwsem.c > @@ -1345,6 +1345,18 @@ static 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)) { > @@ -1495,6 +1507,20 @@ 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();
Acked-by: Waiman Long <longman@redhat.com>
-Longman
| |