17.03.2011 16:01, Trond Myklebust ÐÐÑÐÑ:
On Thu, 2011-03-17 at 15:16 +0300, Stanislav Kinsbursky wrote: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@xxxxxxxxxx> --- 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);Testing for RPC_IS_QUEUED(rovr) would be better, since that would optimise away the call to rpc_wake_up_queued_task() altogether for those tasks that aren't queued.
Yes, I agree with testing RPC_IS_QUEUED(rovr) since such approach looks clearer and in 2.6.38 tk_waitqueue is initialized prior to set RPC_TASK_QUEUED bit. But I found this problem in 2.6.32 rhel kernel where this set sequence is inversed. Will send fixed version soon.
} } spin_unlock(&clnt->cl_lock);
-- Best regards, Stanislav Kinsbursky -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
