netdev - Re: 2.6.20->2.6.21 - networking dies after random time

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Date:	Thu, 26 Jul 2007 10:31:20 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Jarek Poplawski <jarkao2@...pl>,
	Marcin ??lusarz <marcin.slusarz@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	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>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: 2.6.20->2.6.21 - networking dies after random time


* Thomas Gleixner <tglx@...utronix.de> wrote:

> The other question is:
> 
> Is the driver confused by the resent irq or is the chip-set unhappy 
> about the resend ?
> 
> We could figure the latter out by activating the software based resend 
> method.

yeah. The patch below enables sw-resend on x86, to test the theory 
whether the APIC-driven hardware-vector-resend code has some problem.

Marcin, could you please give this one a try too? Good behavior would be 
a fully working kernel (no hung device) with no extra kernel messages. 
Bad behavior would be any extra kernel message or any non-working 
device.

	Ingo

----------------------------->
Subject: x86: activate HARDIRQS_SW_RESEND
From: Ingo Molnar <mingo@...e.hu>

activate the software-triggered IRQ-resend logic.

it appears some chipsets/cpus do not handle local-APIC driven IRQ
resends all that well, so always use the soft mechanism to trigger
the execution of pending interrupts.

Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/i386/Kconfig   |    4 ++++
 kernel/irq/manage.c |    8 ++++++++
 2 files changed, 12 insertions(+)

Index: linux/arch/i386/Kconfig
===================================================================
--- linux.orig/arch/i386/Kconfig
+++ linux/arch/i386/Kconfig
@@ -1270,6 +1270,10 @@ config GENERIC_PENDING_IRQ
 	depends on GENERIC_HARDIRQS && SMP
 	default y
 
+config HARDIRQS_SW_RESEND
+	bool
+	default y
+
 config X86_SMP
 	bool
 	depends on SMP && !X86_VOYAGER
Index: linux/kernel/irq/manage.c
===================================================================
--- linux.orig/kernel/irq/manage.c
+++ linux/kernel/irq/manage.c
@@ -181,6 +181,14 @@ void enable_irq(unsigned int irq)
 		desc->depth--;
 	}
 	spin_unlock_irqrestore(&desc->lock, flags);
+#ifdef CONFIG_HARDIRQS_SW_RESEND
+	/*
+	 * Do a bh disable/enable pair to trigger any pending
+	 * irq resend logic:
+	 */
+	local_bh_disable();
+	local_bh_enable();
+#endif
 }
 EXPORT_SYMBOL(enable_irq);
 
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