tree 7efa266f81f6b68861bbea6cbda6baec48267408
parent 4718787d1f626f45ddb239912bc07266b9880044
author Davidlohr Bueso <davidlohr.bueso@hp.com> 1378934786 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1378940383 -0700

ipc: document general ipc locking scheme

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>