Commit e509bd7d authored by Mika Westerberg's avatar Mika Westerberg Committed by Thomas Gleixner

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: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/1444039935-30475-1-git-send-email-mika.westerberg@linux.intel.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 9e7e2b0a
...@@ -21,6 +21,20 @@ ...@@ -21,6 +21,20 @@
#include "internals.h" #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_set_chip - set the irq chip for an irq
* @irq: irq number * @irq: irq number
...@@ -746,6 +760,8 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle, ...@@ -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) if (desc->irq_data.chip != &no_irq_chip)
mask_ack_irq(desc); mask_ack_irq(desc);
irq_state_set_disabled(desc); irq_state_set_disabled(desc);
if (is_chained)
desc->action = NULL;
desc->depth = 1; desc->depth = 1;
} }
desc->handle_irq = handle; desc->handle_irq = handle;
...@@ -755,6 +771,7 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t 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_noprobe(desc);
irq_settings_set_norequest(desc); irq_settings_set_norequest(desc);
irq_settings_set_nothread(desc); irq_settings_set_nothread(desc);
desc->action = &chained_action;
irq_startup(desc, true); irq_startup(desc, true);
} }
} }
......
...@@ -18,6 +18,8 @@ ...@@ -18,6 +18,8 @@
extern bool noirqdebug; extern bool noirqdebug;
extern struct irqaction chained_action;
/* /*
* Bits used by threaded handlers: * Bits used by threaded handlers:
* IRQTF_RUNTHREAD - signals that the interrupt handler thread should run * IRQTF_RUNTHREAD - signals that the interrupt handler thread should run
......
...@@ -460,7 +460,7 @@ int show_interrupts(struct seq_file *p, void *v) ...@@ -460,7 +460,7 @@ int show_interrupts(struct seq_file *p, void *v)
for_each_online_cpu(j) for_each_online_cpu(j)
any_count |= kstat_irqs_cpu(i, j); any_count |= kstat_irqs_cpu(i, j);
action = desc->action; action = desc->action;
if (!action && !any_count) if ((!action || action == &chained_action) && !any_count)
goto out; goto out;
seq_printf(p, "%*d: ", prec, i); seq_printf(p, "%*d: ", prec, i);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment