From: Vasiliy Kulikov <segoon@openwall.com>
Date: Wed, 3 Aug 2011 18:28:26 +0000 (+0400)
Subject: shm: optimize exit_shm()
X-Git-Tag: v3.1-rc1~44
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=298507d4d2cff2248e84afcf646b697301294442;p=pandora-kernel.git

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>
---

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