Commit-ID: 17fcbd590d0c3e35bd9646e2215f86586378bc42
Gitweb: http://git.kernel.org/tip/17fcbd590d0c3e35bd9646e2215f86586378bc42
Author: Niklas Cassel <[email protected]>
AuthorDate: Sat, 25 Feb 2017 01:17:53 +0100
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 16 Mar 2017 09:28:30 +0100
locking/rwsem: Fix down_write_killable() for CONFIG_RWSEM_GENERIC_SPINLOCK=y
We hang if SIGKILL has been sent, but the task is stuck in down_read()
(after do_exit()), even though no task is doing down_write() on the
rwsem in question:
INFO: task libupnp:21868 blocked for more than 120 seconds.
libupnp D 0 21868 1 0x08100008
...
Call Trace:
__schedule()
schedule()
__down_read()
do_exit()
do_group_exit()
__wake_up_parent()
This bug has already been fixed for CONFIG_RWSEM_XCHGADD_ALGORITHM=y in
the following commit:
04cafed7fc19 ("locking/rwsem: Fix down_write_killable()")
... however, this bug also exists for CONFIG_RWSEM_GENERIC_SPINLOCK=y.
Signed-off-by: Niklas Cassel <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Niklas Cassel <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: d47996082f52 ("locking/rwsem: Introduce basis for down_write_killable()")
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
kernel/locking/rwsem-spinlock.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
index 7bc24d4..c65f798 100644
--- a/kernel/locking/rwsem-spinlock.c
+++ b/kernel/locking/rwsem-spinlock.c
@@ -213,10 +213,9 @@ int __sched __down_write_common(struct rw_semaphore *sem,
int state)
*/
if (sem->count == 0)
break;
- if (signal_pending_state(state, current)) {
- ret = -EINTR;
- goto out;
- }
+ if (signal_pending_state(state, current))
+ goto out_nolock;
+
set_current_state(state);
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
schedule();
@@ -224,12 +223,19 @@ int __sched __down_write_common(struct rw_semaphore *sem,
int state)
}
/* got the lock */
sem->count = -1;
-out:
list_del(&waiter.list);
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
return ret;
+
+out_nolock:
+ list_del(&waiter.list);
+ if (!list_empty(&sem->wait_list))
+ __rwsem_do_wake(sem, 1);
+ raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+ return -EINTR;
}
void __sched __down_write(struct rw_semaphore *sem)
