Commit 540a0f75 authored by Trond Myklebust's avatar Trond Myklebust

SUNRPC: We must not use list_for_each_entry_safe() in rpc_wake_up()

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: default avatarAndy Adamson <andros@netapp.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org
parent e49a29bd
...@@ -534,14 +534,18 @@ EXPORT_SYMBOL_GPL(rpc_wake_up_next); ...@@ -534,14 +534,18 @@ EXPORT_SYMBOL_GPL(rpc_wake_up_next);
*/ */
void rpc_wake_up(struct rpc_wait_queue *queue) void rpc_wake_up(struct rpc_wait_queue *queue)
{ {
struct rpc_task *task, *next;
struct list_head *head; struct list_head *head;
spin_lock_bh(&queue->lock); spin_lock_bh(&queue->lock);
head = &queue->tasks[queue->maxpriority]; head = &queue->tasks[queue->maxpriority];
for (;;) { 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); rpc_wake_up_task_queue_locked(queue, task);
}
if (head == &queue->tasks[0]) if (head == &queue->tasks[0])
break; break;
head--; head--;
...@@ -559,13 +563,16 @@ EXPORT_SYMBOL_GPL(rpc_wake_up); ...@@ -559,13 +563,16 @@ EXPORT_SYMBOL_GPL(rpc_wake_up);
*/ */
void rpc_wake_up_status(struct rpc_wait_queue *queue, int status) void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
{ {
struct rpc_task *task, *next;
struct list_head *head; struct list_head *head;
spin_lock_bh(&queue->lock); spin_lock_bh(&queue->lock);
head = &queue->tasks[queue->maxpriority]; head = &queue->tasks[queue->maxpriority];
for (;;) { 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; task->tk_status = status;
rpc_wake_up_task_queue_locked(queue, task); rpc_wake_up_task_queue_locked(queue, task);
} }
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment