From 76e677e25dd3d8af77d0b3810eacaacaf2f93f2f Mon Sep 17 00:00:00 2001 From: Bryan Sutula Date: Wed, 5 Oct 2005 11:02:06 -0600 Subject: [PATCH] [IA64] Avoid kernel hang during CMC interrupt storm I've noticed a kernel hang during a storm of CMC interrupts, which was tracked down to the continual execution of the interrupt handler. There's code in the CMC handler that's supposed to disable CMC interrupts and switch to polling mode when it sees a bunch of CMCs. Because disabling CMCs across all CPUs isn't safe in interrupt context, the disable is done with a schedule_work(). But with continual CMC interrupts, the schedule_work() never gets executed. The following patch immediately disables CMC interrupts for the current CPU. This then allows (at least) one CPU to ignore CMC interrupts, execute the schedule_work() code, and disable CMC interrupts on the rest of the CPUs. Acked-by: Keith Owens Signed-off-by: Bryan Sutula Signed-off-by: Tony Luck --- arch/ia64/kernel/mca.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/ia64/kernel/mca.c b/arch/ia64/kernel/mca.c index 6dc726ad7137..d0a5106fba24 100644 --- a/arch/ia64/kernel/mca.c +++ b/arch/ia64/kernel/mca.c @@ -1016,6 +1016,11 @@ ia64_mca_cmc_int_handler(int cmc_irq, void *arg, struct pt_regs *ptregs) cmc_polling_enabled = 1; spin_unlock(&cmc_history_lock); + /* If we're being hit with CMC interrupts, we won't + * ever execute the schedule_work() below. Need to + * disable CMC interrupts on this processor now. + */ + ia64_mca_cmc_vector_disable(NULL); schedule_work(&cmc_disable_work); /*