mm: make lru_add_drain_all() selective

[cascardo/linux.git] / ipc / util.c

diff --git a/ipc/util.c b/ipc/util.c
index 9a1d779..e829da9 100644 (file)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -15,6 +15,14 @@
  * Jun 2006 - namespaces ssupport
  *            OpenVZ, SWsoft Inc.
  *            Pavel Emelianov <xemul@openvz.org>
+ *
+ * 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>
@@ -197,7 +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;
        }
 
@@ -677,22 +686,6 @@ out:
        return out;
 }
 
-struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
-{
-       struct kern_ipc_perm *out;
-
-       out = ipc_lock(ids, id);
-       if (IS_ERR(out))
-               return out;
-
-       if (ipc_checkid(out, id)) {
-               ipc_unlock(out);
-               return ERR_PTR(-EIDRM);
-       }
-
-       return out;
-}
-
 /**
  * ipcget - Common sys_*get() code
  * @ns : namsepace
@@ -830,7 +823,8 @@ 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;
                }
        }