[PATCH] SUNRPC: Fix potential deadlock in RPC code
In rpc_wake_up() and rpc_wake_up_status(), it is possible for the call to
__rpc_wake_up_task() to fail if another thread happens to be calling
rpc_wake_up_task() on the same rpc_task.
Problem noticed by Bruno Faccini.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 802d4fe..e838d04 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -515,16 +515,14 @@
*/
void rpc_wake_up(struct rpc_wait_queue *queue)
{
- struct rpc_task *task;
-
+ struct rpc_task *task, *next;
struct list_head *head;
+
spin_lock_bh(&queue->lock);
head = &queue->tasks[queue->maxpriority];
for (;;) {
- while (!list_empty(head)) {
- task = list_entry(head->next, struct rpc_task, u.tk_wait.list);
+ list_for_each_entry_safe(task, next, head, u.tk_wait.list)
__rpc_wake_up_task(task);
- }
if (head == &queue->tasks[0])
break;
head--;
@@ -541,14 +539,13 @@
*/
void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
{
+ struct rpc_task *task, *next;
struct list_head *head;
- struct rpc_task *task;
spin_lock_bh(&queue->lock);
head = &queue->tasks[queue->maxpriority];
for (;;) {
- while (!list_empty(head)) {
- task = list_entry(head->next, struct rpc_task, u.tk_wait.list);
+ list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
task->tk_status = status;
__rpc_wake_up_task(task);
}