linux-kernel - Re: 2.6.20->2.6.21 - networking dies after random time

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Message-ID: <20070724094202.GA11610@elte.hu>
Date:	Tue, 24 Jul 2007 11:42:02 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Marcin ??lusarz <marcin.slusarz@...il.com>
Cc:	Jarek Poplawski <jarkao2@...pl>,
	Jean-Baptiste Vignaud <vignaud@...dmail.fr>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	shemminger <shemminger@...ux-foundation.org>,
	linux-net <linux-net@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: 2.6.20->2.6.21 - networking dies after random time


* Ingo Molnar <mingo@...e.hu> wrote:

> thanks for tracking it down! Could you try the patch below (ontop an 
> otherwise unmodified kernel)? This tests the theory whether the 
> problem is related to the disable_irq_nosync() call in the ne2k 
> driver's xmit path. Does this solve the hangs too?

please try the patch below instead.

	Ingo

Index: linux/kernel/irq/chip.c
===================================================================
--- linux.orig/kernel/irq/chip.c
+++ linux/kernel/irq/chip.c
@@ -231,7 +231,7 @@ static void default_enable(unsigned int 
 /*
  * default disable function
  */
-static void default_disable(unsigned int irq)
+void default_disable(unsigned int irq)
 {
 }
 
Index: linux/kernel/irq/internals.h
===================================================================
--- linux.orig/kernel/irq/internals.h
+++ linux/kernel/irq/internals.h
@@ -10,6 +10,8 @@ extern void irq_chip_set_defaults(struct
 /* Set default handler: */
 extern void compat_irq_chip_set_default_handler(struct irq_desc *desc);
 
+extern void default_disable(unsigned int irq);
+
 #ifdef CONFIG_PROC_FS
 extern void register_irq_proc(unsigned int irq);
 extern void register_handler_proc(unsigned int irq, struct irqaction *action);
Index: linux/kernel/irq/manage.c
===================================================================
--- linux.orig/kernel/irq/manage.c
+++ linux/kernel/irq/manage.c
@@ -102,7 +102,19 @@ void disable_irq_nosync(unsigned int irq
 	spin_lock_irqsave(&desc->lock, flags);
 	if (!desc->depth++) {
 		desc->status |= IRQ_DISABLED;
-		desc->chip->disable(irq);
+		/*
+		 * the _nosync variant of irq-disable suggests that the
+		 * caller is not worried about concurrency but about the
+		 * ordering of the irq flow itself. (such as hardware
+		 * getting confused about certain, normally valid irq
+		 * handling sequences.) So if the default disable handler
+		 * is in place then try the more conservative masking
+		 * instead:
+		 */
+		if (desc->chip->disable == default_disable && desc->chip->mask)
+			desc->chip->mask(irq);
+		else
+			desc->chip->disable(irq);
 	}
 	spin_unlock_irqrestore(&desc->lock, flags);
 }
-
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