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authorTrond Myklebust <Trond.Myklebust@netapp.com>2012-03-19 13:39:35 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2012-03-19 14:15:02 -0400
commit540a0f7584169651f485e8ab67461fcb06934e38 (patch)
tree5a5dede243b80f1dca55f651ff2a78eaccff5c50 /net/sunrpc
parente49a29bd0eacce9d4956c4daf777a330115b369d (diff)
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: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: stable@vger.kernel.org
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/sched.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 1c570a81096a..994cfea2bad6 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -534,14 +534,18 @@ 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--;
@@ -559,13 +563,16 @@ 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);
}