This is a note to let you know that I've just added the patch titled
SUNRPC: We must not use list_for_each_entry_safe() in rpc_wake_up()
to the 3.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sunrpc-we-must-not-use-list_for_each_entry_safe-in-rpc_wake_up.patch
and it can be found in the queue-3.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 540a0f7584169651f485e8ab67461fcb06934e38 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <[email protected]>
Date: Mon, 19 Mar 2012 13:39:35 -0400
Subject: SUNRPC: We must not use list_for_each_entry_safe() in rpc_wake_up()
From: Trond Myklebust <[email protected]>
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 <[email protected]>
Signed-off-by: Trond Myklebust <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/sunrpc/sched.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -501,14 +501,18 @@ 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--;
@@ -526,13 +530,16 @@ 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);
}
Patches currently in stable-queue which might be from
[email protected] are
queue-3.3/sunrpc-we-must-not-use-list_for_each_entry_safe-in-rpc_wake_up.patch
queue-3.3/nfsv4-return-the-delegation-if-the-server-returns-nfs4err_openmode.patch
queue-3.3/nfs-properly-handle-the-case-where-the-delegation-is-revoked.patch
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