tree 15861e6610403c57cf4eca976dea4d59ac7a8e99
parent 33a30ed4bdccd95ed84a1a20c1fef8ac89788ce5
author Vasiliy Kulikov <segoon@openwall.com> 1312396106 +0400
committer Linus Torvalds <torvalds@linux-foundation.org> 1312418755 -1000

shm: optimize exit_shm()

We may optimistically check .in_use == 0 without holding the rw_mutex:
it's the common case, and if it's zero, there certainly won't be any
segments associated with us.

After taking the lock, the idr_for_each() will do the right thing, so we
could now drop the re-check inside the lock without any real cost.  But
it won't hurt.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>