[PATCH] thinko in APIC_LOCKUP_DEBUG can cause SMP hang (2.4.7+)

[James Bottomley]

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This one looks like it would trip if the lockup debug code encounters a shared 
level interrupt which would cause it to loop forever.

James Bottomley

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Index: arch/i386/kernel/io_apic.c
===================================================================
RCS file: /home/jejb/CVSROOT/linux/2.4/arch/i386/kernel/io_apic.c,v
retrieving revision 1.1.1.22
diff -u -r1.1.1.22 io_apic.c
--- arch/i386/kernel/io_apic.c	2001/09/25 23:59:50	1.1.1.22
+++ arch/i386/kernel/io_apic.c	2001/10/31 01:34:49
@@ -1236,6 +1236,9 @@
 	ack_APIC_irq();
 
 	if (!(v & (1 << (i & 0x1f)))) {
+#ifdef APIC_LOCKUP_DEBUG
+		struct irq_pin_list *entry = irq_2_pin + irq;
+#endif
 #ifdef APIC_MISMATCH_DEBUG
 		atomic_inc(&irq_mis_count);
 #endif
@@ -1243,7 +1246,6 @@
 		__mask_and_edge_IO_APIC_irq(irq);
 #ifdef APIC_LOCKUP_DEBUG
 		for (;;) {
-			struct irq_pin_list *entry = irq_2_pin + irq;
 			unsigned int reg;
 
 			if (entry->pin == -1)

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