path: root/arch/mips/kernel/irq_cpu.c
diff options
authorRalf Baechle <ralf@linux-mips.org>2007-11-15 19:37:15 +0000
committerRalf Baechle <ralf@linux-mips.org>2007-11-15 23:21:52 +0000
commit30e748a507919a41f9eb4d10b4954f453325a37d (patch)
treea499fb079d632e401d8313caa229e899f6a251b3 /arch/mips/kernel/irq_cpu.c
parent[MIPS] Sibyte: Fix name of clocksource. (diff)
[MIPS] irq_cpu: use handle_percpu_irq handler to avoid dropping interrupts.
This matters to any sort of device that is wired to one of the CPU interrupt pins on an SMP system. Typically the scenario is most easily triggered with the count/compare timer interrupt where the same interrupt number and thus irq_desc is used on each processor. CPU A CPU B do_IRQ() generic_handle_irq() handle_level_irq() spin_lock(desc_lock) set IRQ_INPROGRESS spin_unlock(desc_lock) do_IRQ() generic_handle_irq() handle_level_irq() spin_lock(desc_lock) IRQ_INPROGRESS set => bail out spin_lock(desc_lock) clear IRQ_INPROGRESS spin_unlock(desc_lock) In case of the cp0 compare interrupt this means the interrupt will be acked and not handled or re-armed on CPU b, so there won't be any timer interrupt until the count register wraps around. With kernels 2.6.20 ... 2.6.23 we usually were lucky that things were just working right on VSMP because the count registers are synchronized on bootup so it takes something that disables interrupts for a long time on one processor to trigger this one. For scenarios where an interrupt is multicasted or broadcasted over several CPUs the existing code was safe and the fix will break it. There is no way to know in the interrupt controller code because it is abstracted from the platform code. I think we do not have such a setup currently, so this should be ok. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/irq_cpu.c')
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/mips/kernel/irq_cpu.c b/arch/mips/kernel/irq_cpu.c
index 7b66e03b5899..0ee2567b780d 100644
--- a/arch/mips/kernel/irq_cpu.c
+++ b/arch/mips/kernel/irq_cpu.c
@@ -116,5 +116,5 @@ void __init mips_cpu_irq_init(void)
for (i = irq_base + 2; i < irq_base + 8; i++)
set_irq_chip_and_handler(i, &mips_cpu_irq_controller,
- handle_level_irq);
+ handle_percpu_irq);