[PATCH] smp_call_function_single() check that local interrupts are enabled
smp_call_function_single() can deadlock if the caller disabled local
interrupts (the target CPU could be spinning on call_lock). Check for that.
Why on earth do these functions use spin_lock_bh()??
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/kernel/smp.c b/arch/i386/kernel/smp.c
index 31e5c65..9827cf9 100644
--- a/arch/i386/kernel/smp.c
+++ b/arch/i386/kernel/smp.c
@@ -699,6 +699,10 @@
put_cpu();
return -EBUSY;
}
+
+ /* Can deadlock when called with interrupts disabled */
+ WARN_ON(irqs_disabled());
+
spin_lock_bh(&call_lock);
__smp_call_function_single(cpu, func, info, nonatomic, wait);
spin_unlock_bh(&call_lock);