From e03b2c37702a406580d63e7092d9894c665c23c2 Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Mon, 5 Oct 2015 13:12:15 +0300 Subject: [PATCH] genirq: Allow migration of chained interrupts by installing default action When a CPU is offlined all interrupts that have an action are migrated to other still online CPUs. However, if the interrupt has chained handler installed this is not done. Chained handlers are used by GPIO drivers which support interrupts, for instance. When the affinity is not corrected properly we end up in situation where most interrupts are not arriving to the online CPUs anymore. For example on Intel Braswell system which has SD-card card detection signal connected to a GPIO the IO-APIC routing entries look like below after CPU1 is offlined: pin30, enabled , level, low , V(52), IRR(0), S(0), logical , D(03), M(1) pin31, enabled , level, low , V(42), IRR(0), S(0), logical , D(03), M(1) pin32, enabled , level, low , V(62), IRR(0), S(0), logical , D(03), M(1) pin5b, enabled , level, low , V(72), IRR(0), S(0), logical , D(03), M(1) The problem here is that the destination mask still contains both CPUs even if CPU1 is already offline. This means that the IO-APIC still routes interrupts to the other CPU as well. We solve the problem by providing a default action for chained interrupts. This action allows the migration code to correct affinity (as it finds desc->action != NULL). Also make the default action handler to emit a warning if for some reason a chained handler ends up calling it. Signed-off-by: Mika Westerberg Cc: Jiang Liu Link: http://lkml.kernel.org/r/1444039935-30475-1-git-send-email-mika.westerberg@linux.intel.com Signed-off-by: Thomas Gleixner --- kernel/irq/chip.c | 17 +++++++++++++++++ kernel/irq/internals.h | 2 ++ kernel/irq/proc.c | 2 +- 3 files changed, 20 insertions(+), 1 deletion(-) diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index 46f1fb505b168..4aa00d325b8c8 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -21,6 +21,20 @@ #include "internals.h" +static irqreturn_t bad_chained_irq(int irq, void *dev_id) +{ + WARN_ONCE(1, "Chained irq %d should not call an action\n", irq); + return IRQ_NONE; +} + +/* + * Chained handlers should never call action on their IRQ. This default + * action will emit warning if such thing happens. + */ +struct irqaction chained_action = { + .handler = bad_chained_irq, +}; + /** * irq_set_chip - set the irq chip for an irq * @irq: irq number @@ -746,6 +760,8 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle, if (desc->irq_data.chip != &no_irq_chip) mask_ack_irq(desc); irq_state_set_disabled(desc); + if (is_chained) + desc->action = NULL; desc->depth = 1; } desc->handle_irq = handle; @@ -755,6 +771,7 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle, irq_settings_set_noprobe(desc); irq_settings_set_norequest(desc); irq_settings_set_nothread(desc); + desc->action = &chained_action; irq_startup(desc, true); } } diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index cd60bb48397f9..05c2188271b86 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -18,6 +18,8 @@ extern bool noirqdebug; +extern struct irqaction chained_action; + /* * Bits used by threaded handlers: * IRQTF_RUNTHREAD - signals that the interrupt handler thread should run diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c index e3a8c9577ba64..7d6090519630b 100644 --- a/kernel/irq/proc.c +++ b/kernel/irq/proc.c @@ -460,7 +460,7 @@ int show_interrupts(struct seq_file *p, void *v) for_each_online_cpu(j) any_count |= kstat_irqs_cpu(i, j); action = desc->action; - if (!action && !any_count) + if ((!action || action == &chained_action) && !any_count) goto out; seq_printf(p, "%*d: ", prec, i); -- 2.39.5