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authorTrond Myklebust <Trond.Myklebust@netapp.com>2012-01-17 22:57:37 -0500
committerTrond Myklebust <Trond.Myklebust@netapp.com>2012-01-31 19:28:08 -0500
commit961a828df64979d2a9faeeeee043391670a193b9 (patch)
tree4b7ddaf1a19c589e3c8ec96b6c732faa507f2899 /net/sunrpc/sched.c
parent2aeb98f498ce37742b743080fdc6c8cf64053599 (diff)
SUNRPC: Fix potential races in xprt_lock_write_next()
We have to ensure that the wake up from the waitqueue and the assignment of xprt->snd_task are atomic. We can do this by assigning the snd_task while under the waitqueue spinlock. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'net/sunrpc/sched.c')
-rw-r--r--net/sunrpc/sched.c42
1 files changed, 33 insertions, 9 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 3341d8962786..f982dfe53993 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -422,7 +422,7 @@ EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
/*
* Wake up the next task on a priority queue.
*/
-static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
+static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
{
struct list_head *q;
struct rpc_task *task;
@@ -467,30 +467,54 @@ new_queue:
new_owner:
rpc_set_waitqueue_owner(queue, task->tk_owner);
out:
- rpc_wake_up_task_queue_locked(queue, task);
return task;
}
+static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
+{
+ if (RPC_IS_PRIORITY(queue))
+ return __rpc_find_next_queued_priority(queue);
+ if (!list_empty(&queue->tasks[0]))
+ return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
+ return NULL;
+}
+
/*
- * Wake up the next task on the wait queue.
+ * Wake up the first task on the wait queue.
*/
-struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
+struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
+ bool (*func)(struct rpc_task *, void *), void *data)
{
struct rpc_task *task = NULL;
- dprintk("RPC: wake_up_next(%p \"%s\")\n",
+ dprintk("RPC: wake_up_first(%p \"%s\")\n",
queue, rpc_qname(queue));
spin_lock_bh(&queue->lock);
- if (RPC_IS_PRIORITY(queue))
- task = __rpc_wake_up_next_priority(queue);
- else {
- task_for_first(task, &queue->tasks[0])
+ task = __rpc_find_next_queued(queue);
+ if (task != NULL) {
+ if (func(task, data))
rpc_wake_up_task_queue_locked(queue, task);
+ else
+ task = NULL;
}
spin_unlock_bh(&queue->lock);
return task;
}
+EXPORT_SYMBOL_GPL(rpc_wake_up_first);
+
+static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
+{
+ return true;
+}
+
+/*
+ * Wake up the next task on the wait queue.
+*/
+struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
+{
+ return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
+}
EXPORT_SYMBOL_GPL(rpc_wake_up_next);
/**