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Date: Tue, 2 Feb 2016 21:19:29 +0100 From: Michal Hocko <mhocko@...nel.org> To: LKML <linux-kernel@...r.kernel.org> Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, "H. Peter Anvin" <hpa@...or.com>, "David S. Miller" <davem@...emloft.net>, Tony Luck <tony.luck@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, Chris Zankel <chris@...kel.net>, Max Filippov <jcmvbkbc@...il.com>, x86@...nel.org, linux-alpha@...r.kernel.org, linux-ia64@...r.kernel.org, linux-s390@...r.kernel.org, linux-sh@...r.kernel.org, sparclinux@...r.kernel.org, linux-xtensa@...ux-xtensa.org, linux-arch@...r.kernel.org, Michal Hocko <mhocko@...e.com> Subject: [RFC 12/12] locking, rwsem: provide down_write_killable From: Michal Hocko <mhocko@...e.com> Now that all the architectures implement the necessary glue code we can introduce down_write_killable. The only difference wrt. regular down_write is that the slow path waits in TASK_KILLABLE state and the interruption by the fatal signal is reported as -EINTR to the caller. Signed-off-by: Michal Hocko <mhocko@...e.com> --- include/linux/lockdep.h | 15 +++++++++++++++ include/linux/rwsem.h | 1 + kernel/locking/rwsem.c | 19 +++++++++++++++++++ 3 files changed, 35 insertions(+) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index c57e424d914b..f6bd57c0784b 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -446,6 +446,18 @@ do { \ lock_acquired(&(_lock)->dep_map, _RET_IP_); \ } while (0) +#define LOCK_CONTENDED_RETURN(_lock, try, lock) \ +({ \ + int ____err = 0; \ + if (!try(_lock)) { \ + lock_contended(&(_lock)->dep_map, _RET_IP_); \ + ____err = lock(_lock); \ + } \ + if (!____err) \ + lock_acquired(&(_lock)->dep_map, _RET_IP_); \ + ____err; \ +}) + #else /* CONFIG_LOCK_STAT */ #define lock_contended(lockdep_map, ip) do {} while (0) @@ -454,6 +466,9 @@ do { \ #define LOCK_CONTENDED(_lock, try, lock) \ lock(_lock) +#define LOCK_CONTENDED_RETURN(_lock, try, lock) \ + lock(_lock) + #endif /* CONFIG_LOCK_STAT */ #ifdef CONFIG_LOCKDEP diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 7d7ae029dac5..d1c12d160ace 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -118,6 +118,7 @@ extern int down_read_trylock(struct rw_semaphore *sem); * lock for writing */ extern void down_write(struct rw_semaphore *sem); +extern int __must_check down_write_killable(struct rw_semaphore *sem); /* * trylock for writing -- returns 1 if successful, 0 if contention diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 205be0ce34de..c817216c1615 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -55,6 +55,25 @@ void __sched down_write(struct rw_semaphore *sem) EXPORT_SYMBOL(down_write); /* + * lock for writing + */ +int __sched down_write_killable(struct rw_semaphore *sem) +{ + might_sleep(); + rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); + + if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock, __down_write_killable)) { + rwsem_release(&sem->dep_map, 1, _RET_IP_); + return -EINTR; + } + + rwsem_set_owner(sem); + return 0; +} + +EXPORT_SYMBOL(down_write_killable); + +/* * trylock for writing -- returns 1 if successful, 0 if contention */ int down_write_trylock(struct rw_semaphore *sem) -- 2.7.0
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