diff options
| author | Davidlohr Bueso <[email protected]> | 2013-09-11 14:26:26 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2013-09-11 15:59:43 -0700 |
| commit | 05603c44a7627793219b0bd9a7b236099dc9cd9d (patch) | |
| tree | 7efa266f81f6b68861bbea6cbda6baec48267408 | |
| parent | 4718787d1f626f45ddb239912bc07266b9880044 (diff) | |
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 <[email protected]>
Tested-by: Sedat Dilek <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | ipc/util.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/ipc/util.c b/ipc/util.c index 9a1d779a20e2..1ddadcf9a2ab 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -15,6 +15,14 @@ * Jun 2006 - namespaces ssupport * OpenVZ, SWsoft Inc. * Pavel Emelianov <[email protected]> + * + * General sysv ipc locking scheme: + * when doing ipc id lookups, take the ids->rwsem + * rcu_read_lock() + * obtain the ipc object (kern_ipc_perm) + * perform security, capabilities, auditing and permission checks, etc. + * acquire the ipc lock (kern_ipc_perm.lock) throught ipc_lock_object() + * perform data updates (ie: SET, RMID, LOCK/UNLOCK commands) */ #include <linux/mm.h> |