ipc: rename ipcctl_pre_down_nolock()

Both the comment and the name of ipcctl_pre_down_nolock() are misleading:
The function must be called while holdling the rw semaphore.

Therefore the patch renames the function to ipcctl_obtain_check(): This
name matches the other names used in util.c:

- "obtain" function look up a pointer in the idr, without
  acquiring the object lock.
- The caller is responsible for locking.
- _check means that the sequence number is checked.

Link: http://lkml.kernel.org/r/20180712185241.4017-5-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 8 insertions, 8 deletions

diff --git a/ipc/msg.c b/ipc/msg.c
index 3132aa27ff88..b9b47d6cd7ee 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -386,7 +386,7 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
         down_write(&msg_ids(ns).rwsem);
         rcu_read_lock();
 
-        ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
+        ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd,
                                       &msqid64->msg_perm, msqid64->msg_qbytes);
         if (IS_ERR(ipcp)) {
                 err = PTR_ERR(ipcp);
diff --git a/ipc/sem.c b/ipc/sem.c
index 8e72037b894a..cf2ba4509f0d 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1596,7 +1596,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
         down_write(&sem_ids(ns).rwsem);
         rcu_read_lock();
 
-        ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd,
+        ipcp = ipcctl_obtain_check(ns, &sem_ids(ns), semid, cmd,
                                       &semid64->sem_perm, 0);
         if (IS_ERR(ipcp)) {
                 err = PTR_ERR(ipcp);
diff --git a/ipc/shm.c b/ipc/shm.c
index 6e7bd9830549..a413ddf74dac 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -881,7 +881,7 @@ static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
         down_write(&shm_ids(ns).rwsem);
         rcu_read_lock();
 
-        ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
+        ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
                                       &shmid64->shm_perm, 0);
         if (IS_ERR(ipcp)) {
                 err = PTR_ERR(ipcp);
diff --git a/ipc/util.c b/ipc/util.c
index 465bbd21d234..1d88dffd75e7 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -688,7 +688,7 @@ int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 }
 
 /**
- * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
+ * ipcctl_obtain_check - retrieve an ipc object and check permissions
  * @ns:  ipc namespace
  * @ids:  the table of ids where to look for the ipc
  * @id:   the id of the ipc to retrieve
@@ -698,16 +698,16 @@ int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
  *
  * This function does some common audit and permissions check for some IPC_XXX
  * cmd and is called from semctl_down, shmctl_down and msgctl_down.
- * It must be called without any lock held and:
  *
- *   - retrieves the ipc with the given id in the given table.
+ * It:
+ *   - retrieves the ipc object with the given id in the given table.
  *   - performs some audit and permission check, depending on the given cmd
  *   - returns a pointer to the ipc object or otherwise, the corresponding
  *     error.
  *
  * Call holding the both the rwsem and the rcu read lock.
  */
-struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
+struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
                                         struct ipc_ids *ids, int id, int cmd,
                                         struct ipc64_perm *perm, int extra_perm)
 {
diff --git a/ipc/util.h b/ipc/util.h
index 0aba3230d007..fcf81425ae98 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -148,7 +148,7 @@ struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
-struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
+struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
                                              struct ipc_ids *ids, int id, int cmd,
                                              struct ipc64_perm *perm, int extra_perm);