Messages in this thread Patch in this message | | | Subject | [PATCH] RPC: killing RPC tasks races fixed | From | Stanislav Kinsbursky <> | Date | Thu, 17 Mar 2011 15:16:55 +0300 |
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task->tk_waitqueue must be checked for NULL before trying to wake up task in rpc_killall_tasks() because it can be NULL.
Here is an example:
CPU 0 CPU 1 CPU 2 -------------------- --------------------- -------------------------- nfs4_run_open_task rpc_run_task rpc_execute rpc_set_active rpc_make_runnable (waiting) rpc_async_schedule nfs4_open_prepare nfs_wait_on_sequence nfs_umount_begin rpc_killall_tasks rpc_wake_up_task rpc_wake_up_queued_task spin_lock(tk_waitqueue == NULL) BUG() rpc_sleep_on spin_lock(&q->lock) __rpc_sleep_on task->tk_waitqueue = q
Signed-off-by: Stanislav Kinsbursky <skinsbursky@openvz.org>
--- net/sunrpc/clnt.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 57d344c..24039fe 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -436,7 +436,9 @@ void rpc_killall_tasks(struct rpc_clnt *clnt) if (!(rovr->tk_flags & RPC_TASK_KILLED)) { rovr->tk_flags |= RPC_TASK_KILLED; rpc_exit(rovr, -EIO); - rpc_wake_up_queued_task(rovr->tk_waitqueue, rovr); + if (rovr->tk_waitqueue) + rpc_wake_up_queued_task(rovr->tk_waitqueue, + rovr); } } spin_unlock(&clnt->cl_lock);
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