Commit-ID: 76f8507f7a6442215df19de74f07eabca2462f1e Gitweb: https://git.kernel.org/tip/76f8507f7a6442215df19de74f07eabca2462f1e Author: Kirill Tkhai <ktk...@virtuozzo.com> AuthorDate: Fri, 29 Sep 2017 19:06:38 +0300 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 10 Oct 2017 11:50:16 +0200
locking/rwsem: Add down_read_killable() Similar to down_read() and down_write_killable(), add killable version of down_read(), based on __down_read_killable() function, added in previous patches. Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: a...@arndb.de Cc: ava...@virtuozzo.com Cc: da...@davemloft.net Cc: fenghua...@intel.com Cc: gorcu...@virtuozzo.com Cc: heiko.carst...@de.ibm.com Cc: h...@zytor.com Cc: i...@jurassic.park.msu.ru Cc: matts...@gmail.com Cc: rient...@google.com Cc: r...@twiddle.net Cc: schwidef...@de.ibm.com Cc: tony.l...@intel.com Cc: v...@zeniv.linux.org.uk Link: http://lkml.kernel.org/r/150670119884.23930.2585570605960763239.stgit@localhost.localdomain Signed-off-by: Ingo Molnar <mi...@kernel.org> --- include/asm-generic/rwsem.h | 10 ++++++++++ include/linux/rwsem.h | 1 + kernel/locking/rwsem.c | 16 ++++++++++++++++ 3 files changed, 27 insertions(+) diff --git a/include/asm-generic/rwsem.h b/include/asm-generic/rwsem.h index 6c6a214..b2d68d2 100644 --- a/include/asm-generic/rwsem.h +++ b/include/asm-generic/rwsem.h @@ -37,6 +37,16 @@ static inline void __down_read(struct rw_semaphore *sem) rwsem_down_read_failed(sem); } +static inline int __down_read_killable(struct rw_semaphore *sem) +{ + if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) { + if (IS_ERR(rwsem_down_read_failed_killable(sem))) + return -EINTR; + } + + return 0; +} + static inline int __down_read_trylock(struct rw_semaphore *sem) { long tmp; diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 0ad7318..6ac8ee5 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -111,6 +111,7 @@ 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_killable(struct rw_semaphore *sem); /* * trylock for reading -- returns 1 if successful, 0 if contention diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 4d48b1c..e53f7746 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -28,6 +28,22 @@ void __sched down_read(struct rw_semaphore *sem) EXPORT_SYMBOL(down_read); +int __sched down_read_killable(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_killable)) { + rwsem_release(&sem->dep_map, 1, _RET_IP_); + return -EINTR; + } + + rwsem_set_reader_owned(sem); + return 0; +} + +EXPORT_SYMBOL(down_read_killable); + /* * trylock for reading -- returns 1 if successful, 0 if contention */
