Merge branch 'fixes-jgarzik' of git://git.kernel.org/pub/scm/linux/kernel/git/linvill...

[linux-2.6] / kernel / irq / manage.c

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 80eab7a0420597ec0c27fe7eaefe12a5868674b9..1f314221d534be091d809628b39f12ccba4e997e 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -29,12 +29,28 @@
 void synchronize_irq(unsigned int irq)
 {
        struct irq_desc *desc = irq_desc + irq;
+       unsigned int status;
 
        if (irq >= NR_IRQS)
                return;
 
-       while (desc->status & IRQ_INPROGRESS)
-               cpu_relax();
+       do {
+               unsigned long flags;
+
+               /*
+                * Wait until we're out of the critical section.  This might
+                * give the wrong answer due to the lack of memory barriers.
+                */
+               while (desc->status & IRQ_INPROGRESS)
+                       cpu_relax();
+
+               /* Ok, that indicated we're done: double-check carefully. */
+               spin_lock_irqsave(&desc->lock, flags);
+               status = desc->status;
+               spin_unlock_irqrestore(&desc->lock, flags);
+
+               /* Oops, that failed? */
+       } while (status & IRQ_INPROGRESS);
 }
 EXPORT_SYMBOL(synchronize_irq);