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ARM: 7872/1: Support arch_irq_work_raise() via self IPIs 

By default, IRQ work is run from the tick interrupt (see
irq_work_run() in update_process_times()). When we're in full
NOHZ mode, restarting the tick requires the use of IRQ work and
if the only place we run IRQ work is in the tick interrupt we
have an unbreakable cycle. Implement arch_irq_work_raise() via
self IPIs to break this cycle and get the tick started again.
Note that we implement this via IPIs which are only available on
SMP builds. This shouldn't be a problem because full NOHZ is only
supported on SMP builds anyway.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Stephen Boyd 2013-10-29 20:32:56 +01:00 committed by Russell King
parent 8d45144254
commit bf18525fd7
2 changed files with 19 additions and 1 deletions
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2
arch/arm/include/asm/hardirq.h
View File

@ -5,7 +5,7 @@
#include <linux/threads.h>
#include <asm/irq.h>
#define NR_IPI 6
#define NR_IPI 7
typedef struct {
unsigned int __softirq_pending;

18
arch/arm/kernel/smp.c
View File

@ -25,6 +25,7 @@
#include <linux/clockchips.h>
#include <linux/completion.h>
#include <linux/cpufreq.h>
#include <linux/irq_work.h>
#include <linux/atomic.h>
#include <asm/smp.h>
@ -66,6 +67,7 @@ enum ipi_msg_type {
IPI_CALL_FUNC,
IPI_CALL_FUNC_SINGLE,
IPI_CPU_STOP,
IPI_IRQ_WORK,
};
static DECLARE_COMPLETION(cpu_running);
@ -448,6 +450,13 @@ void arch_send_call_function_single_ipi(int cpu)
smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
}
#ifdef CONFIG_IRQ_WORK
void arch_irq_work_raise(void)
{
smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
}
#endif
static const char *ipi_types[NR_IPI] = {
#define S(x,s) [x] = s
S(IPI_WAKEUP, "CPU wakeup interrupts"),
@ -456,6 +465,7 @@ static const char *ipi_types[NR_IPI] = {
S(IPI_CALL_FUNC, "Function call interrupts"),
S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
S(IPI_CPU_STOP, "CPU stop interrupts"),
S(IPI_IRQ_WORK, "IRQ work interrupts"),
};
void show_ipi_list(struct seq_file *p, int prec)
@ -565,6 +575,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
irq_exit();
break;
#ifdef CONFIG_IRQ_WORK
case IPI_IRQ_WORK:
irq_enter();
irq_work_run();
irq_exit();
break;
#endif
default:
printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
cpu, ipinr);