This is a note to let you know that I've just added the patch titled
SUNRPC: Fix a race between work-queue and rpc_killall_tasks
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
sunrpc-fix-a-race-between-work-queue-and-rpc_killall_tasks.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <sta...@kernel.org> know about it.
>From b55c59892e1f3b6c7d4b9ccffb4263e1486fb990 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.mykleb...@netapp.com>
Date: Wed, 6 Jul 2011 19:58:23 -0400
Subject: SUNRPC: Fix a race between work-queue and rpc_killall_tasks
From: Trond Myklebust <trond.mykleb...@netapp.com>
commit b55c59892e1f3b6c7d4b9ccffb4263e1486fb990 upstream.
Since rpc_killall_tasks may modify the rpc_task's tk_action field
without any locking, we need to be careful when dereferencing it.
Reported-by: Ben Greear <gree...@candelatech.com>
Tested-by: Ben Greear <gree...@candelatech.com>
Signed-off-by: Trond Myklebust <trond.mykleb...@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gre...@suse.de>
---
net/sunrpc/sched.c | 27 +++++++++++----------------
1 file changed, 11 insertions(+), 16 deletions(-)
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -613,30 +613,25 @@ static void __rpc_execute(struct rpc_tas
BUG_ON(RPC_IS_QUEUED(task));
for (;;) {
+ void (*do_action)(struct rpc_task *);
/*
- * Execute any pending callback.
+ * Execute any pending callback first.
*/
- if (task->tk_callback) {
- void (*save_callback)(struct rpc_task *);
-
- /*
- * We set tk_callback to NULL before calling it,
- * in case it sets the tk_callback field itself:
- */
- save_callback = task->tk_callback;
- task->tk_callback = NULL;
- save_callback(task);
- } else {
+ do_action = task->tk_callback;
+ task->tk_callback = NULL;
+ if (do_action == NULL) {
/*
* Perform the next FSM step.
- * tk_action may be NULL when the task has been killed
- * by someone else.
+ * tk_action may be NULL if the task has been killed.
+ * In particular, note that rpc_killall_tasks may
+ * do this at any time, so beware when dereferencing.
*/
- if (task->tk_action == NULL)
+ do_action = task->tk_action;
+ if (do_action == NULL)
break;
- task->tk_action(task);
}
+ do_action(task);
/*
* Lockless check for whether task is sleeping or not.
Patches currently in longterm-queue-2.6.32 which might be from
trond.mykleb...@netapp.com are
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/sunrpc-fix-use-of-static-variable-in-rpcb_getport_async.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/sunrpc-fix-a-race-between-work-queue-and-rpc_killall_tasks.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/nfsv4.1-update-nfs4_fattr_bitmap_maxsz.patch
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