af_unix: Revert 'lock_interruptible' in stream receive code
With b3ca9b02b00704053a38bfe4c31dbbb9c13595d0, the AF_UNIX SOCK_STREAM
receive code was changed from using mutex_lock(&u->readlock) to
mutex_lock_interruptible(&u->readlock) to prevent signals from being
delayed for an indefinite time if a thread sleeping on the mutex
happened to be selected for handling the signal. But this was never a
problem with the stream receive code (as opposed to its datagram
counterpart) as that never went to sleep waiting for new messages with the
mutex held and thus, wouldn't cause secondary readers to block on the
mutex waiting for the sleeping primary reader. As the interruptible
locking makes the code more complicated in exchange for no benefit,
change it back to using mutex_lock.
Signed-off-by: Rainer Weikusat <email address hidden>
Acked-by: Hannes Frederic Sowa <email address hidden>
Signed-off-by: David S. Miller <email address hidden>
This is the commit that introduced this regression in V4.4-rc6:
commit 3822b5c2fc62e3d e8a0f33806ff279 fb7df92432
Author: Rainer Weikusat <email address hidden>
Date: Wed Dec 16 20:09:25 2015 +0000
af_unix: Revert 'lock_interrupt ible' in stream receive code
With b3ca9b02b007040 53a38bfe4c31dbb b9c13595d0, the AF_UNIX SOCK_STREAM &u->readlock) to lock_interrupti ble(&u- >readlock) to prevent signals from being
receive code was changed from using mutex_lock(
mutex_
delayed for an indefinite time if a thread sleeping on the mutex
happened to be selected for handling the signal. But this was never a
problem with the stream receive code (as opposed to its datagram
counterpart) as that never went to sleep waiting for new messages with the
mutex held and thus, wouldn't cause secondary readers to block on the
mutex waiting for the sleeping primary reader. As the interruptible
locking makes the code more complicated in exchange for no benefit,
change it back to using mutex_lock.
Signed-off-by: Rainer Weikusat <email address hidden>
Acked-by: Hannes Frederic Sowa <email address hidden>
Signed-off-by: David S. Miller <email address hidden>