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authorNadia Derbey <Nadia.Derbey@bull.net>2008-07-25 01:48:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 10:53:42 -0700
commit983bfb7db303cfde56ae5bbf4e0f2f46e38c9576 (patch)
treed107ca3c03e2c84e3d58c6f9e53879d3486e9c5f
parentcf481c20c476ad2c0febdace9ce23f5a4db19582 (diff)
downloadconfigs-983bfb7db303cfde56ae5bbf4e0f2f46e38c9576.tar.gz
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>
-rw-r--r--ipc/util.c9
1 files changed, 0 insertions, 9 deletions
diff --git a/ipc/util.c b/ipc/util.c
index 3339177b336..0f468c34e83 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -688,10 +688,6 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
* 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 *ipc_lock(struct ipc_ids *ids, int id)
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