[PATCH][PPC32] Don't synchronize in disable_irq() if no handler

[Paul Mackerras]

This patch is the ppc32 counterpart to a fix that went into
arch/i386/kernel/irq.c last October.  The bug was noted by Al Viro: if
no handler exists, and we have IRQ_INPROGRESS set because of an
earlier irq that got through, synchronize_irq() will end up waiting
forever.

Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>

diff -urN linux-2.5/arch/ppc/kernel/irq.c pmac-2.5/arch/ppc/kernel/irq.c
--- linux-2.5/arch/ppc/kernel/irq.c	2004-02-23 12:05:11.000000000 +1100
+++ pmac-2.5/arch/ppc/kernel/irq.c	2004-03-11 16:49:24.000000000 +1100
@@ -304,8 +304,10 @@
 
 void disable_irq(unsigned int irq)
 {
+	irq_desc_t *desc = irq_desc + irq;
 	disable_irq_nosync(irq);
-	synchronize_irq(irq);
+	if (desc->action)
+		synchronize_irq(irq);
 }
 
 /**
-
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