linux-kernel - [PATCH 06/12] ipc: rename ipc_lock() to ipc_lock

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Date:   Mon,  9 Jul 2018 17:10:13 +0200
From:   Manfred Spraul <manfred@...orfullife.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        Dmitry Vyukov <dvyukov@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, 1vier1@....de,
        Kees Cook <keescook@...omium.org>,
        Manfred Spraul <manfred@...orfullife.com>
Subject: [PATCH 06/12] ipc: rename ipc_lock() to ipc_lock_idr()

ipc/util.c contains multiple functions to get the ipc object
pointer given an id number.

There are two sets of function: One set verifies the sequence
counter part of the id number, other functions do not check
the sequence counter.

The standard for function names in ipc/util.c is
- ..._check() functions verify the sequence counter
- ..._idr() functions do not verify the sequence counter

ipc_lock() is an exception: It does not verify the sequence
counter value, but this is not obvious from the function name.

Therefore: Rename the function to ipc_lock_idr(), to make it
obvious that it does not check the sequence counter.

Signed-off-by: Manfred Spraul <manfred@...orfullife.com>
Cc: Davidlohr Bueso <dave@...olabs.net>
---
 ipc/shm.c  |  4 ++--
 ipc/util.c | 10 ++++++----
 ipc/util.h |  2 +-
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index 426ba1039a7b..cd8655c7bb77 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -179,11 +179,11 @@ static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace
  */
 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
-	struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
+	struct kern_ipc_perm *ipcp = ipc_lock_idr(&shm_ids(ns), id);
 
 	/*
 	 * Callers of shm_lock() must validate the status of the returned ipc
-	 * object pointer (as returned by ipc_lock()), and error out as
+	 * object pointer (as returned by ipc_lock_idr()), and error out as
 	 * appropriate.
 	 */
 	if (IS_ERR(ipcp))
diff --git a/ipc/util.c b/ipc/util.c
index 8133f10832a9..8bc166bb4981 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -604,15 +604,17 @@ struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
 }
 
 /**
- * ipc_lock - lock an ipc structure without rwsem held
+ * ipc_lock_idr - lock an ipc structure without rwsem 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 function does not check if the sequence counter matches the
+ * found ipc object.
  *
  * The ipc object is locked on successful exit.
  */
-struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
+struct kern_ipc_perm *ipc_lock_idr(struct ipc_ids *ids, int id)
 {
 	struct kern_ipc_perm *out;
 
@@ -624,8 +626,8 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 	spin_lock(&out->lock);
 
 	/*
-	 * ipc_rmid() may have already freed the ID while ipc_lock()
-	 * was spinning: here verify that the structure is still valid.
+	 * ipc_rmid() may have already freed the ID while waiting for
+	 * the lock. Here verify that the structure is still valid.
 	 * Upon races with RMID, return -EIDRM, thus indicating that
 	 * the ID points to a removed identifier.
 	 */
diff --git a/ipc/util.h b/ipc/util.h
index fcf81425ae98..25d8ee052ac9 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -142,7 +142,7 @@ int ipc_rcu_getref(struct kern_ipc_perm *ptr);
 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 			void (*func)(struct rcu_head *head));
 
-struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
+struct kern_ipc_perm *ipc_lock_idr(struct ipc_ids *ids, int id);
 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);
-- 
2.17.1