path: root/kernel/irq/internals.h
diff options
authorMika Westerberg <>2015-10-05 13:12:15 +0300
committerThomas Gleixner <>2015-10-09 22:47:27 +0200
commite509bd7da149dc34916037484cd7545b2d48a2b0 (patch)
treec6f5acf97add574cdfa76ab64438fd6717c6ee9f /kernel/irq/internals.h
parent9e7e2b0a6a005941a6854cdabae19c3d9e069dbe (diff)
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: Signed-off-by: Thomas Gleixner <>
Diffstat (limited to 'kernel/irq/internals.h')
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index cd60bb48397f..05c2188271b8 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