linux-kernel - [S390] prevent softirqs if delay is called disabled

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Message-ID: <20070221100022.GB13419@skybase>
Date:	Wed, 21 Feb 2007 11:00:22 +0100
From:	Martin Schwidefsky <schwidefsky@...ibm.com>
To:	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Subject: [S390] prevent softirqs if delay is called disabled

From: Martin Schwidefsky <schwidefsky@...ibm.com>

[S390] prevent softirqs if delay is called disabled

The new delay implementation uses the clock comparator and an external
interrupt even if it is called disabled for interrupts. To do this
all external interrupt source except clock comparator are switched of
before enabling external interrupts. The external interrupt at the
end of the delay period may not execute softirqs or we can end up in a
dead-lock.

Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
---

 arch/s390/lib/delay.c |    7 +++++++
 1 files changed, 7 insertions(+)

diff -urpN linux-2.6/arch/s390/lib/delay.c linux-2.6-patched/arch/s390/lib/delay.c
--- linux-2.6/arch/s390/lib/delay.c	2007-02-21 10:47:06.000000000 +0100
+++ linux-2.6-patched/arch/s390/lib/delay.c	2007-02-21 10:47:23.000000000 +0100
@@ -15,6 +15,7 @@
 #include <linux/delay.h>
 #include <linux/timex.h>
 #include <linux/irqflags.h>
+#include <linux/interrupt.h>
 
 void __delay(unsigned long loops)
 {
@@ -35,7 +36,11 @@ void __udelay(unsigned long usecs)
 {
 	u64 end, time, jiffy_timer = 0;
 	unsigned long flags, cr0, mask, dummy;
+	int irq_context;
 
+	irq_context = in_interrupt();
+	if (!irq_context)
+		local_bh_disable();
 	local_irq_save(flags);
 	if (raw_irqs_disabled_flags(flags)) {
 		jiffy_timer = S390_lowcore.jiffy_timer;
@@ -62,6 +67,8 @@ void __udelay(unsigned long usecs)
 		__ctl_load(cr0, 0, 0);
 		S390_lowcore.jiffy_timer = jiffy_timer;
 	}
+	if (!irq_context)
+		_local_bh_enable();
 	set_clock_comparator(S390_lowcore.jiffy_timer);
 	local_irq_restore(flags);
 }
-- 
blue skies,              IBM Deutschland Entwicklung GmbH
   Martin                Vorsitzender des Aufsichtsrats: Johann Weihen
                         Geschäftsführung: Herbert Kircher 
Martin Schwidefsky       Sitz der Gesellschaft: Böblingen
Linux on zSeries         Registergericht: Amtsgericht Stuttgart,
   Development           HRB 243294
   
"Reality continues to ruin my life." - Calvin.

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