From 76f8507f7a6442215df19de74f07eabca2462f1e Mon Sep 17 00:00:00 2001 From: Kirill Tkhai Date: Fri, 29 Sep 2017 19:06:38 +0300 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: arnd@arndb.de Cc: avagin@virtuozzo.com Cc: davem@davemloft.net Cc: fenghua.yu@intel.com Cc: gorcunov@virtuozzo.com Cc: heiko.carstens@de.ibm.com Cc: hpa@zytor.com Cc: ink@jurassic.park.msu.ru Cc: mattst88@gmail.com Cc: rientjes@google.com Cc: rth@twiddle.net Cc: schwidefsky@de.ibm.com Cc: tony.luck@intel.com Cc: viro@zeniv.linux.org.uk Link: http://lkml.kernel.org/r/150670119884.23930.2585570605960763239.stgit@localhost.localdomain Signed-off-by: Ingo Molnar --- 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 6c6a2141f271..b2d68d2d198e 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 0ad7318ff299..6ac8ee5f15dd 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 4d48b1c4870d..e53f7746d9fd 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 */