diff options
| author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2012-03-19 13:39:35 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-04-02 09:52:51 -0700 |
| commit | b8d535ac89519bda67bc3cab419a29953b1eb74e (patch) | |
| tree | 39dc40423786933973de4f0774e5372df8961f4e /net/sunrpc/sched.c | |
| parent | 8617e195f2213c885c5aae3578c545a5ace9477b (diff) | |
SUNRPC: We must not use list_for_each_entry_safe() in rpc_wake_up()
commit 540a0f7584169651f485e8ab67461fcb06934e38 upstream.
The problem is that for the case of priority queues, we
have to assume that __rpc_remove_wait_queue_priority will move new
elements from the tk_wait.links lists into the queue->tasks[] list.
We therefore cannot use list_for_each_entry_safe() on queue->tasks[],
since that will skip these new tasks that __rpc_remove_wait_queue_priority
is adding.
Without this fix, rpc_wake_up and rpc_wake_up_status will both fail
to wake up all functions on priority wait queues, which can result
in some nasty hangs.
Reported-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/sunrpc/sched.c')
| -rw-r--r-- | net/sunrpc/sched.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 00a1a2acd58..4e2b3b454ab 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -500,14 +500,18 @@ EXPORT_SYMBOL_GPL(rpc_wake_up_next); */ void rpc_wake_up(struct rpc_wait_queue *queue) { - struct rpc_task *task, *next; struct list_head *head; spin_lock_bh(&queue->lock); head = &queue->tasks[queue->maxpriority]; for (;;) { - list_for_each_entry_safe(task, next, head, u.tk_wait.list) + while (!list_empty(head)) { + struct rpc_task *task; + task = list_first_entry(head, + struct rpc_task, + u.tk_wait.list); rpc_wake_up_task_queue_locked(queue, task); + } if (head == &queue->tasks[0]) break; head--; @@ -525,13 +529,16 @@ EXPORT_SYMBOL_GPL(rpc_wake_up); */ void rpc_wake_up_status(struct rpc_wait_queue *queue, int status) { - struct rpc_task *task, *next; struct list_head *head; spin_lock_bh(&queue->lock); head = &queue->tasks[queue->maxpriority]; for (;;) { - list_for_each_entry_safe(task, next, head, u.tk_wait.list) { + while (!list_empty(head)) { + struct rpc_task *task; + task = list_first_entry(head, + struct rpc_task, + u.tk_wait.list); task->tk_status = status; rpc_wake_up_task_queue_locked(queue, task); } |