ipc/util: drop ipc_rcu_alloc()

No callers remain for ipc_rcu_alloc().  Drop the function.

[manfred@colorfullife.com: Rediff because the memset was temporarily inside ipc_rcu_free()]
Link: http://lkml.kernel.org/r/20170525185107.12869-13-manfred@colorfullife.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/util.c

@@ -394,27 +394,6 @@ void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 	ipcp->deleted = true;
 }
 
-/**
- * ipc_rcu_alloc - allocate ipc space
- * @size: size desired
- *
- * Allocate memory for an ipc object.
- * The first member must be struct kern_ipc_perm.
- */
-struct kern_ipc_perm *ipc_rcu_alloc(int size)
-{
-	/*
-	 * We prepend the allocation with the rcu struct
-	 */
-	struct kern_ipc_perm *out = kvmalloc(size, GFP_KERNEL);
-	if (unlikely(!out))
-		return NULL;
-
-	memset(out, 0, size);
-	atomic_set(&out->refcount, 1);
-	return out;
-}
-
 int ipc_rcu_getref(struct kern_ipc_perm *ptr)
 {
 	return atomic_inc_not_zero(&ptr->refcount);

ipc/util.h

@@ -112,10 +112,7 @@ int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
  * Objects are reference counted, they start with reference count 1.
  * getref increases the refcount, the putref call that reduces the recount
  * to 0 schedules the rcu destruction. Caller must guarantee locking.
- *
- * struct kern_ipc_perm must be the first member in the allocated structure.
  */
-struct kern_ipc_perm *ipc_rcu_alloc(int size);
 int ipc_rcu_getref(struct kern_ipc_perm *ptr);
 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 			void (*func)(struct rcu_head *head));