ipc: drop ipc_lock_by_ptr

After previous cleanups and optimizations, this function is no longer
heavily used and we don't have a good reason to keep it.  Update the few
remaining callers and get rid of it.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: 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>

ipc/namespace.c

@@ -89,7 +89,8 @@ void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 		perm = idr_find(&ids->ipcs_idr, next_id);
 		if (perm == NULL)
 			continue;
-		ipc_lock_by_ptr(perm);
+		rcu_read_lock();
+		ipc_lock_object(perm);
 		free(ns, perm);
 		total++;
 	}

ipc/util.c

@@ -205,7 +205,8 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
 			continue;
 		}
 
-		ipc_lock_by_ptr(ipc);
+		rcu_read_lock();
+		ipc_lock_object(ipc);
 		return ipc;
 	}
 
@@ -838,7 +839,8 @@ static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 		ipc = idr_find(&ids->ipcs_idr, pos);
 		if (ipc != NULL) {
 			*new_pos = pos + 1;
-			ipc_lock_by_ptr(ipc);
+			rcu_read_lock();
+			ipc_lock_object(ipc);
 			return ipc;
 		}
 	}

ipc/util.h

@@ -171,12 +171,6 @@ static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 	assert_spin_locked(&perm->lock);
 }
 
-static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
-{
-	rcu_read_lock();
-	ipc_lock_object(perm);
-}
-
 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 {
 	ipc_unlock_object(perm);