ipc: document general ipc locking scheme
authorDavidlohr Bueso <davidlohr.bueso@hp.com>
Wed, 11 Sep 2013 21:26:26 +0000 (14:26 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 18 Oct 2013 14:45:48 +0000 (07:45 -0700)
commita5daa172ff0897c52eb4c6da18b092c757264b2f
treeaeb3016441cb6024df6a1a283edc762c72d9dcf1
parentc143813735d3246637e4ad60bfd4cf042189b83c
ipc: document general ipc locking scheme

commit 05603c44a7627793219b0bd9a7b236099dc9cd9d upstream.

As suggested by Andrew, add a generic initial locking scheme used
throughout all sysv ipc mechanisms.  Documenting the ids rwsem, how rcu
can be enough to do the initial checks and when to actually acquire the
kern_ipc_perm.lock spinlock.

I found that adding it to util.c was generic enough.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ipc/util.c