The ia64_mca_cpe_int_handler() in 2.6.24 goes something like this: ia64_mca_cpe_int_handler (int cpe_irq, void *arg) { ... /* SAL spec states this should run w/ interrupts enabled */ local_irq_enable(); spin_lock(&cpe_history_lock); ... spin_unlock(&cpe_history_lock); ia64_mca_log_sal_error_record(SAL_INFO_TYPE_CPE); } I think the interrupts are enabled too early. I just have caught a dead lock: I have got nested ia64_mca_cpe_int_handler()-s, the first instance has been interrupted somewhere between spin_lock(&cpe_history_lock) and spin_unlock(&cpe_history_lock). Obviously, the second instance will never get the lock. The previous versions, e.g. 2.6.18, were not safe either: ia64_mca_cpe_int_handler (int cpe_irq, void *arg, struct pt_regs *ptregs) { ... /* SAL spec states this should run w/ interrupts enabled */ local_irq_enable(); /* Get the CPE error record and log it */ ia64_mca_log_sal_error_record(SAL_INFO_TYPE_CPE); spin_lock(&cpe_history_lock); ... spin_unlock(&cpe_history_lock); } I think the interrupts have to be blocked while we are inside the lock- protected region. I can think of something like this below. Please have a look at this patch. Thanks, Zoltan Menyhart
--- linux-2.6.24-old/arch/ia64/kernel/mca.c 2008-02-22 18:09:12.000000000 +0100 +++ linux-2.6.24/arch/ia64/kernel/mca.c 2008-02-22 18:09:26.000000000 +0100 @@ -436,6 +436,10 @@ static const char * const rec_name[] = { "MCA", "INIT", "CMC", "CPE" }; #endif + if (irq_safe){ + /* SAL spec states this should run w/ interrupts enabled */ + local_irq_enable(); + } size = ia64_log_get(sal_info_type, &buffer, irq_safe); if (!size) return; @@ -512,9 +516,6 @@ IA64_MCA_DEBUG("%s: received interrupt vector = %#x on CPU %d\n", __FUNCTION__, cpe_irq, smp_processor_id()); - /* SAL spec states this should run w/ interrupts enabled */ - local_irq_enable(); - spin_lock(&cpe_history_lock); if (!cpe_poll_enabled && cpe_vector >= 0) { @@ -1324,9 +1325,6 @@ IA64_MCA_DEBUG("%s: received interrupt vector = %#x on CPU %d\n", __FUNCTION__, cmc_irq, smp_processor_id()); - /* SAL spec states this should run w/ interrupts enabled */ - local_irq_enable(); - spin_lock(&cmc_history_lock); if (!cmc_polling_enabled) { int i, count = 1; /* we know 1 happened now */
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