Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c642b8391cf8efc3622cc97329a0f46e7cbb70b8
Commit: c642b8391cf8efc3622cc97329a0f46e7cbb70b8
Parent: 57d5f66b86079efac5c9a7843cce2a9bcbe58fb8
Author: Russ Anderson <[EMAIL PROTECTED]>
AuthorDate: Wed Nov 14 17:00:15 2007 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Nov 14 18:45:43 2007 -0800
__do_IRQ does not check IRQ_DISABLED when IRQ_PER_CPU is set
In __do_IRQ(), the normal case is that IRQ_DISABLED is checked and if set
the handler (handle_IRQ_event()) is not called.
Earlier in __do_IRQ(), if IRQ_PER_CPU is set the code does not check
IRQ_DISABLED and calls the handler even though IRQ_DISABLED is set. This
behavior seems unintentional.
One user encountering this behavior is the CPE handler (in
arch/ia64/kernel/mca.c). When the CPE handler encounters too many CPEs
(such as a solid single bit error), it sets up a polling timer and disables
the CPE interrupt (to avoid excessive overhead logging the stream of single
bit errors). disable_irq_nosync() is called which sets IRQ_DISABLED. The
IRQ_PER_CPU flag was previously set (in ia64_mca_late_init()). The net
result is the CPE handler gets called even though it is marked disabled.
If the behavior of not checking IRQ_DISABLED when IRQ_PER_CPU is set is
intentional, it would be worthy of a comment describing the intended
behavior. disable_irq_nosync() does call chip->disable() to provide a
chipset specifiec interface for disabling the interrupt, which avoids this
issue when used.
Signed-off-by: Russ Anderson <[EMAIL PROTECTED]>
Cc: "Luck, Tony" <[EMAIL PROTECTED]>
Cc: Thomas Gleixner <[EMAIL PROTECTED]>
Cc: Ingo Molnar <[EMAIL PROTECTED]>
Cc: Bjorn Helgaas <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
kernel/irq/handle.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index e391cbb..dc335ad 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -178,9 +178,11 @@ fastcall unsigned int __do_IRQ(unsigned int irq)
*/
if (desc->chip->ack)
desc->chip->ack(irq);
- action_ret = handle_IRQ_event(irq, desc->action);
- if (!noirqdebug)
- note_interrupt(irq, desc, action_ret);
+ if (likely(!(desc->status & IRQ_DISABLED))) {
+ action_ret = handle_IRQ_event(irq, desc->action);
+ if (!noirqdebug)
+ note_interrupt(irq, desc, action_ret);
+ }
desc->chip->end(irq);
return 1;
}
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
