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locking/rwsem: Introduce basis for down_write_killable()

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Introduce a generic implementation necessary for down_write_killable().

This is a trivial extension of the already existing down_write() call
which can be interrupted by SIGKILL.  This patch doesn't provide
down_write_killable() yet because arches have to provide the necessary
pieces before.

rwsem_down_write_failed() which is a generic slow path for the
write lock is extended to take a task state and renamed to
__rwsem_down_write_failed_common(). The return value is either a valid
semaphore pointer or ERR_PTR(-EINTR).

rwsem_down_write_failed_killable() is exported as a new way to wait for
the lock and be killable.

For rwsem-spinlock implementation the current __down_write() it updated
in a similar way as __rwsem_down_write_failed_common() except it doesn't
need new exports just visible __down_write_killable().

Architectures which are not using the generic rwsem implementation are
supposed to provide their __down_write_killable() implementation and
use rwsem_down_write_failed_killable() for the slow path.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Signed-off-by: Jason Low <jason.low2@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/1460041951-22347-7-git-send-email-mhocko@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Michal Hocko
2016-04-07 17:12:26 +02:00
committed by Ingo Molnar
parent 938072e32c
commit d47996082f
5 changed files with 60 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
kernel/locking/rwsem-xadd.c
View File

@@ -433,12 +433,13 @@ static inline bool rwsem_has_spinner(struct rw_semaphore *sem)
/*
* Wait until we successfully acquire the write lock
*/
__visible
struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
static inline struct rw_semaphore *
__rwsem_down_write_failed_common(struct rw_semaphore *sem, int state)
{
long count;
bool waiting = true; /* any queued threads before us */
struct rwsem_waiter waiter;
struct rw_semaphore *ret = sem;
/* undo write bias from down_write operation, stop active locking */
count = rwsem_atomic_update(-RWSEM_ACTIVE_WRITE_BIAS, sem);
@@ -478,7 +479,7 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
count = rwsem_atomic_update(RWSEM_WAITING_BIAS, sem);
/* wait until we successfully acquire the lock */
set_current_state(TASK_UNINTERRUPTIBLE);
set_current_state(state);
while (true) {
if (rwsem_try_write_lock(count, sem))
break;
@@ -486,21 +487,39 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
/* Block until there are no active lockers. */
do {
if (signal_pending_state(state, current)) {
raw_spin_lock_irq(&sem->wait_lock);
ret = ERR_PTR(-EINTR);
goto out;
}
schedule();
set_current_state(TASK_UNINTERRUPTIBLE);
set_current_state(state);
} while ((count = sem->count) & RWSEM_ACTIVE_MASK);
raw_spin_lock_irq(&sem->wait_lock);
}
out:
__set_current_state(TASK_RUNNING);
list_del(&waiter.list);
raw_spin_unlock_irq(&sem->wait_lock);
return sem;
return ret;
}
__visible struct rw_semaphore * __sched
rwsem_down_write_failed(struct rw_semaphore *sem)
{
return __rwsem_down_write_failed_common(sem, TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL(rwsem_down_write_failed);
__visible struct rw_semaphore * __sched
rwsem_down_write_failed_killable(struct rw_semaphore *sem)
{
return __rwsem_down_write_failed_common(sem, TASK_KILLABLE);
}
EXPORT_SYMBOL(rwsem_down_write_failed_killable);
/*
* handle waking up a waiter on the semaphore
* - up_read/up_write has decremented the active part of count if we come here