linux-kernel - [PATCH 4/6] ipc/sem.c: Change perform_atomic

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Date:	Sat, 10 May 2014 12:03:17 +0200
From:	Manfred Spraul <manfred@...orfullife.com>
To:	Davidlohr Bueso <davidlohr.bueso@...com>,
	Michael Kerrisk <mtk.manpages@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>, 1vier1@....de,
	Manfred Spraul <manfred@...orfullife.com>
Subject: [PATCH 4/6] ipc/sem.c: Change perform_atomic_semop parameters

Right now, perform_atomic_semop gets the content of sem_queue as individual
fields.
Changes that, instead pass a pointer to sem_queue.

This is a preparation for the next patch: it uses
sem_queue to store the reason why a task must sleep.

Signed-off-by: Manfred Spraul <manfred@...orfullife.com>
---
 ipc/sem.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/ipc/sem.c b/ipc/sem.c
index 821aba7..3962cca 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -585,21 +585,23 @@ SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
 /**
  * perform_atomic_semop - Perform (if possible) a semaphore operation
  * @sma: semaphore array
- * @sops: array with operations that should be checked
- * @nsops: number of operations
- * @un: undo array
- * @pid: pid that did the change
+ * @q: struct sem_queue that describes the operation
  *
  * Returns 0 if the operation was possible.
  * Returns 1 if the operation is impossible, the caller must sleep.
  * Negative values are error codes.
  */
-static int perform_atomic_semop(struct sem_array *sma, struct sembuf *sops,
-			     int nsops, struct sem_undo *un, int pid)
+static int perform_atomic_semop(struct sem_array *sma, struct sem_queue *q)
 {
-	int result, sem_op;
+	int result, sem_op, nsops, pid;
 	struct sembuf *sop;
 	struct sem *curr;
+	struct sembuf *sops;
+	struct sem_undo *un;
+
+	sops = q->sops;
+	nsops = q->nsops;
+	un = q->undo;
 
 	for (sop = sops; sop < sops + nsops; sop++) {
 		curr = sma->sem_base + sop->sem_num;
@@ -627,6 +629,7 @@ static int perform_atomic_semop(struct sem_array *sma, struct sembuf *sops,
 	}
 
 	sop--;
+	pid = q->pid;
 	while (sop >= sops) {
 		sma->sem_base[sop->sem_num].sempid = pid;
 		sop--;
@@ -779,8 +782,7 @@ static int wake_const_ops(struct sem_array *sma, int semnum,
 		q = container_of(walk, struct sem_queue, list);
 		walk = walk->next;
 
-		error = perform_atomic_semop(sma, q->sops, q->nsops,
-						 q->undo, q->pid);
+		error = perform_atomic_semop(sma, q);
 
 		if (error <= 0) {
 			/* operation completed, remove from queue & wakeup */
@@ -892,8 +894,7 @@ again:
 		if (semnum != -1 && sma->sem_base[semnum].semval == 0)
 			break;
 
-		error = perform_atomic_semop(sma, q->sops, q->nsops,
-					 q->undo, q->pid);
+		error = perform_atomic_semop(sma, q);
 
 		/* Does q->sleeper still need to sleep? */
 		if (error > 0)
@@ -1873,8 +1874,13 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
 	if (un && un->semid == -1)
 		goto out_unlock_free;
 
-	error = perform_atomic_semop(sma, sops, nsops, un,
-					task_tgid_vnr(current));
+	queue.sops = sops;
+	queue.nsops = nsops;
+	queue.undo = un;
+	queue.pid = task_tgid_vnr(current);
+	queue.alter = alter;
+
+	error = perform_atomic_semop(sma, &queue);
 	if (error == 0) {
 		/* If the operation was successful, then do
 		 * the required updates.
@@ -1891,12 +1897,6 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
 	 * task into the pending queue and go to sleep.
 	 */
 
-	queue.sops = sops;
-	queue.nsops = nsops;
-	queue.undo = un;
-	queue.pid = task_tgid_vnr(current);
-	queue.alter = alter;
-
 	if (nsops == 1) {
 		struct sem *curr;
 		curr = &sma->sem_base[sops->sem_num];
-- 
1.9.0

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