linux-kernel - long disable of Softirqs in br_forward_delay_timer

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Message-ID: <45AF79AE.1060102@seskion.de>
Date:	Thu, 18 Jan 2007 14:44:14 +0100
From:	Juergen Pfeiffer <j.pfeiffer@...kion.de>
To:	linux-kernel@...r.kernel.org
Subject: long disable of Softirqs in br_forward_delay_timer_expired()

Hi

I had problems in my implementation of Profibus-protocol, because my 
FDL-State machine is implemented in tasklets and
sometimes there were situations, where Soft-Irqs were disabled for 
20-40mS (Coldfire 5485 / 96MHz).
After inserting some testpoints in kernels source, doing dump_stack(), 
when the jiffie-time get longer then 20mS,
i detected the place of the long Soft-Irq disable in function

static void br_forward_delay_timer_expired(..)
inside file "net/bridge/br_stp_timer.c"

It does a
spin_lock_bh(..);
... some functionality;
spin_unlock_bh(..);

Does anybody know, why the functionality inbetween lock/unlock takes so long
(2-4 jiffies @ HZ=100)

Thank You

Juergen Pfeiffer,
Seskion GmbH
Karlsruher Str. 11/1
70771 Leinfelden-Echterdingen
Germany

j.pfeiffer@...kion.de

www.seskion.de

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