Re: Spinlocking patch for in xprt.c

[David S. Miller]

Trond, did you actually look at how this code works before
you made modifications to my fixes?

xprt_lock serializes sleep/wakeup sequences in the xprt code, so you
cannot remove xprt_lock from the sections where I added holding of
xprt_sock_lock to protect the state of xprt->snd_task.  So for
example, this part of your patch is completely bogus and will create
new corruptions and crashes:

@@ -1143,10 +1143,10 @@
 	struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 
 	if (xprt->snd_task && xprt->snd_task == task) {
-		spin_lock(&xprt_lock);
+		spin_lock_bh(&xprt_sock_lock);
 		xprt->snd_task = NULL;
 		rpc_wake_up_next(&xprt->sending);
-		spin_unlock(&xprt_lock);
+		spin_unlock_bh(&xprt_sock_lock);
 	}
 }

You _must_ hold both xprt_lock and xprt_sock_lock in this
section of code, not just one or just the other.

Linus, please do not apply this patch until these issues
are addressed.

Later,
David S. Miller
[e-mail]