[PATCH]: Fix EJUKEBOX handling

[Olaf Kirch <okir@suse.de>]

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Hi all,

this problem still seems to be present in 2.6.12, or am I
missing something?

The patch I've been using is attached below.

Olaf

On Thu, Feb 24, 2005 at 05:08:35AM +0000, Richard J.Farnsworth wrote:
> There seems to be a bug in the 2.6.11-rc code related to the handling
> of nfsd's EJUNKBOX error return.  The code for __rpc_execute in
> net/sunrpc/sched.c looks like:
> 
> =============================
> 
> static int __rpc_execute(struct rpc_task *task)
> {
> 	int		status = 0;
> 
> 	dprintk("RPC: %4d rpc_execute flgs %x\n",
> 				task->tk_pid, task->tk_flags);
> 
> 	BUG_ON(RPC_IS_QUEUED(task));
> 
>  restarted:
> 	while (1) {
> 		/*
> 		 * Garbage collection of pending timers...
> 		 */
> 		rpc_delete_timer(task);
> 
>  .....
> 
> 	if (task->tk_exit) {
> 		lock_kernel();
> >>>>		task->tk_exit(task);
> 		unlock_kernel();
> 		/* If tk_action is non-null, the user wants us to restart */
> 		if (task->tk_action) {
> 			if (!RPC_ASSASSINATED(task)) {
> 				/* Release RPC slot and buffer memory */
> 				if (task->tk_rqstp)
> 					xprt_release(task);
> 				rpc_free(task);
> 				goto restarted;
> 			}
> 			printk(KERN_ERR "RPC: dead task tries to walk away.\n");
> 		}
> 	}
> 
> =============================
> 
> If the tk_exit procedure (e.g., nfs_read_done) called at ">>>>" above
> detects EJUKEBOX as the result of the call, it will attempt to do
> an rpc_restart and rpc_delay on the task.  The rpc_delay will set a timer.
> However, when the main loop is re-entered via the "goto restarted",
> the first thing that happens is that all timers for the task are removed.
> This results in the RPC task hanging in an uninterruptible wait.
> 
> Am I missing something here or is this really a problem?
> 
> 
> 
> 
> 
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-- 
Olaf Kirch   |  --- o --- Nous sommes du soleil we love when we play
okir@suse.de |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax

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From: Olaf Kirch <okir@suse.de>
Subject: NFS: prevent hangs when NFS server returns EJUKEBOX

When an NFS server returns EJUKEBOX, we restart the RPC task, setting
a delay of a few seconds so that the call is retried a little later.
Unfortunately, we will kill the timer immediately afterwards when we
re-enter the main loop in __rpc_execute.

The fix below will kill the timer only when the task is actually
running.

Signed-off-by: okir@suse.de

Index: linux-2.6.10/net/sunrpc/sched.c
===================================================================
--- linux-2.6.10.orig/net/sunrpc/sched.c
+++ linux-2.6.10/net/sunrpc/sched.c
@@ -569,7 +569,8 @@ static int __rpc_execute(struct rpc_task
 		/*
 		 * Garbage collection of pending timers...
 		 */
-		rpc_delete_timer(task);
+		if (RPC_IS_RUNNING(task))
+			rpc_delete_timer(task);
 
 		/*
 		 * Execute any pending callback.