Re: RT and Cascade interrupts

[john cooper <john.cooper@timesys.com>]

Trond Myklebust wrote:

> I've appended a patch that
> should check for strict compliance of the above rules. Could you try it
> out and see if it triggers any Oopses?

Yes, the assert in rpc_delete_timer() occurs just before
the cascade list corruption.  This is consistent with
what I have seen.  ie: the timer in a released rpc_task
is still active.

BTW, the patch from Oleg is relative to 2.6.12 and didn't
look to apply to the 2.6.11-derived base with which I'm
working (the RPC_IS_QUEUED() test at the head of rpc_delete_timer()
does not exist).  In any case the relocation of restarted: in
__rpc_execute() did not influence the failure.  I'd like to
move to a 2.6.12-based -RT patch however I'm dealing with
"code in the pipe" and unfortunately don't have that option.

Sorry I'm just responding new.  We're in the middle of a
long holiday weekend.  I will have more time come tomorrow
to analyze this further.

-john


> ------------------------------------------------------------------------
> 
>  sched.c |    8 ++++++++
>  1 files changed, 8 insertions(+)
> 
> Index: linux-2.6.12-rc4/net/sunrpc/sched.c
> ===================================================================
> --- linux-2.6.12-rc4.orig/net/sunrpc/sched.c
> +++ linux-2.6.12-rc4/net/sunrpc/sched.c
> @@ -135,6 +135,8 @@ __rpc_add_timer(struct rpc_task *task, r
>  static void
>  rpc_delete_timer(struct rpc_task *task)
>  {
> +	BUG_ON(test_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate) == 0 &&
> +			timer_pending(&task->tk_timer));
>  	if (RPC_IS_QUEUED(task))
>  		return;
>  	if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
> @@ -337,6 +339,8 @@ static void __rpc_sleep_on(struct rpc_wa
>  void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
>  				rpc_action action, rpc_action timer)
>  {
> +	BUG_ON(test_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate) != 0 ||
> +			timer_pending(&task->tk_timer));
>  	/*
>  	 * Protect the queue operations.
>  	 */
> @@ -594,6 +598,8 @@ static int __rpc_execute(struct rpc_task
>  			unlock_kernel();
>  		}
>  
> +		BUG_ON(test_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate) != 0 ||
> +			timer_pending(&task->tk_timer));
>  		/*
>  		 * Perform the next FSM step.
>  		 * tk_action may be NULL when the task has been killed
> @@ -925,6 +931,8 @@ fail:
>  
>  void rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
>  {
> +	BUG_ON(test_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate) != 0 ||
> +			timer_pending(&task->tk_timer));
>  	spin_lock_bh(&childq.lock);
>  	/* N.B. Is it possible for the child to have already finished? */
>  	__rpc_sleep_on(&childq, task, func, NULL);


-- 
john.cooper@timesys.com