[PATCH 8/9] Call idr_find() without locking in ipc_lock()

[Nadia . Derbey]

[PATCH 08/09]

This patch makes idr_find() called locklessly in ipc_lock(), since the idr
tree is now RCU protected.

Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>

---
 ipc/util.c |    9 ---------
 1 file changed, 9 deletions(-)

Index: linux-2.6.25-mm1/ipc/util.c
===================================================================
--- linux-2.6.25-mm1.orig/ipc/util.c	2008-05-06 17:15:10.000000000 +0200
+++ linux-2.6.25-mm1/ipc/util.c	2008-05-07 09:56:20.000000000 +0200
@@ -688,10 +688,6 @@ void ipc64_perm_to_ipc_perm (struct ipc6
  * 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 ip
 	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

--
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