ipc: get rid of ipc_lock_down()

Remove the ipc_lock_down() routines: they used to call idr_find() locklessly
(given that the ipc ids lock was already held), so they are not needed
anymore.

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>

3 files changed, 4 insertions, 75 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index a726aebce7d7..e77ec698cf40 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -112,23 +112,8 @@ void __init shm_init (void)
 }
 
 /*
- * shm_lock_(check_)down routines are called in the paths where the rw_mutex
- * is held to protect access to the idr tree.
- */
-static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns,
-                                                int id)
-{
-        struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id);
-
-        if (IS_ERR(ipcp))
-                return (struct shmid_kernel *)ipcp;
-
-        return container_of(ipcp, struct shmid_kernel, shm_perm);
-}
-
-/*
  * shm_lock_(check_) routines are called in the paths where the rw_mutex
- * is not held.
+ * is not necessarily held.
  */
 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
@@ -211,7 +196,7 @@ static void shm_close(struct vm_area_struct *vma)
 
         down_write(&shm_ids(ns).rw_mutex);
         /* remove from the list of attaches of the shm segment */
-        shp = shm_lock_down(ns, sfd->id);
+        shp = shm_lock(ns, sfd->id);
         BUG_ON(IS_ERR(shp));
         shp->shm_lprid = task_tgid_vnr(current);
         shp->shm_dtim = get_seconds();
@@ -932,7 +917,7 @@ invalid:
 
 out_nattch:
         down_write(&shm_ids(ns).rw_mutex);
-        shp = shm_lock_down(ns, shmid);
+        shp = shm_lock(ns, shmid);
         BUG_ON(IS_ERR(shp));
         shp->shm_nattch--;
         if(shp->shm_nattch == 0 &&
diff --git a/ipc/util.c b/ipc/util.c
index 0f468c34e83c..49b3ea615dc5 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -716,56 +716,6 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
         return out;
 }
 
-/**
- * ipc_lock_down - Lock an ipc structure with rw_sem held
- * @ids: IPC identifier set
- * @id: ipc id to look for
- *
- * 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 already
- * held, i.e. idr tree protected.
- */
-
-struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id)
-{
-        struct kern_ipc_perm *out;
-        int lid = ipcid_to_idx(id);
-
-        rcu_read_lock();
-        out = idr_find(&ids->ipcs_idr, lid);
-        if (out == NULL) {
-                rcu_read_unlock();
-                return ERR_PTR(-EINVAL);
-        }
-
-        spin_lock(&out->lock);
-
-        /*
-         * No need to verify that the structure is still valid since the
-         * rw_mutex is held.
-         */
-        return out;
-}
-
-struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id)
-{
-        struct kern_ipc_perm *out;
-
-        out = ipc_lock_down(ids, id);
-        if (IS_ERR(out))
-                return out;
-
-        if (ipc_checkid(out, id)) {
-                ipc_unlock(out);
-                return ERR_PTR(-EIDRM);
-        }
-
-        return out;
-}
-
 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
 {
         struct kern_ipc_perm *out;
@@ -837,7 +787,7 @@ struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
         int err;
 
         down_write(&ids->rw_mutex);
-        ipcp = ipc_lock_check_down(ids, id);
+        ipcp = ipc_lock_check(ids, id);
         if (IS_ERR(ipcp)) {
                 err = PTR_ERR(ipcp);
                 goto out_up;
diff --git a/ipc/util.h b/ipc/util.h
index cdb966aebe07..3646b45a03c9 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -102,11 +102,6 @@ void* ipc_rcu_alloc(int size);
 void ipc_rcu_getref(void *ptr);
 void ipc_rcu_putref(void *ptr);
 
-/*
- * ipc_lock_down: called with rw_mutex held
- * ipc_lock: called without that lock held
- */
-struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 
 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
@@ -155,7 +150,6 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)
         rcu_read_unlock();
 }
 
-struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id);
 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
                         struct ipc_ops *ops, struct ipc_params *params);