ipc: call idr_find() without locking in ipc_lock()
Call idr_find() locklessly from ipc_lock(), since the idr tree is now RCU
protected.
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Jim Houston <jim.houston@comcast.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/ipc/util.c b/ipc/util.c
index 3339177..0f468c3 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -688,10 +688,6 @@
* Look for an id in the ipc ids idr and lock the associated ipc object.
*
* The ipc object is locked on exit.
- *
- * This is the routine that should be called when the rw_mutex is not already
- * held, i.e. idr tree not protected: it protects the idr tree in read mode
- * during the idr_find().
*/
struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
@@ -699,18 +695,13 @@
struct kern_ipc_perm *out;
int lid = ipcid_to_idx(id);
- down_read(&ids->rw_mutex);
-
rcu_read_lock();
out = idr_find(&ids->ipcs_idr, lid);
if (out == NULL) {
rcu_read_unlock();
- up_read(&ids->rw_mutex);
return ERR_PTR(-EINVAL);
}
- up_read(&ids->rw_mutex);
-
spin_lock(&out->lock);
/* ipc_rmid() may have already freed the ID while ipc_lock
