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MIPS: SMP: Don't increment irq_count multiple times for call function IPIs 

The majority of SMP platforms handle their IPIs through do_IRQ()
which calls irq_{enter/exit}(). When a call function IPI is received,
smp_call_function_interrupt() is called which also calls
irq_{enter,exit}(), meaning irq_count is raised twice.

When tick broadcasting is used (which is implemented via a call
function IPI), this incorrectly causes all CPU idle time on the core
receiving broadcast ticks to be accounted as time spent servicing
IRQs, as account_process_tick() will account as such if irq_count is
greater than 1. This results in 100% CPU usage being reported on a
core which receives its ticks via broadcast.

This patch removes the SMP smp_call_function_interrupt() wrapper which
calls irq_{enter,exit}(). Platforms which handle their IPIs through
do_IRQ() now call generic_smp_call_function_interrupt() directly to
avoid incrementing irq_count a second time. Platforms which don't
(loongson, sgi-ip27, sibyte) call generic_smp_call_function_interrupt()
wrapped in irq_{enter,exit}().

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10770/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Alex Smith 2015-07-24 16:57:49 +01:00 committed by Ralf Baechle
parent 55fdcb2d56
commit 4ace6139bf
14 changed files with 30 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/mips/cavium-octeon/smp.c
View File

@ -42,7 +42,7 @@ static irqreturn_t mailbox_interrupt(int irq, void *dev_id)
cvmx_write_csr(CVMX_CIU_MBOX_CLRX(coreid), action);
if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
if (action & SMP_RESCHEDULE_YOURSELF)
scheduler_ipi();

2
arch/mips/include/asm/smp.h
View File

@ -83,8 +83,6 @@ static inline void __cpu_die(unsigned int cpu)
extern void play_dead(void);
#endif
extern asmlinkage void smp_call_function_interrupt(void);
static inline void arch_send_call_function_single_ipi(int cpu)
{
extern struct plat_smp_ops *mp_ops; /* private */

4
arch/mips/kernel/smp-bmips.c
View File

@ -284,7 +284,7 @@ static irqreturn_t bmips5000_ipi_interrupt(int irq, void *dev_id)
if (action == 0)
scheduler_ipi();
else
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}
@ -336,7 +336,7 @@ static irqreturn_t bmips43xx_ipi_interrupt(int irq, void *dev_id)
if (action & SMP_RESCHEDULE_YOURSELF)
scheduler_ipi();
if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}

10
arch/mips/kernel/smp.c
View File

@ -192,16 +192,6 @@ asmlinkage void start_secondary(void)
cpu_startup_entry(CPUHP_ONLINE);
}
/*
* Call into both interrupt handlers, as we share the IPI for them
*/
void __irq_entry smp_call_function_interrupt(void)
{
irq_enter();
generic_smp_call_function_interrupt();
irq_exit();
}
static void stop_this_cpu(void *dummy)
{
/*

2
arch/mips/lantiq/irq.c
View File

@ -293,7 +293,7 @@ static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
{
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}

7
arch/mips/loongson64/loongson-3/smp.c
View File

@ -266,8 +266,11 @@ void loongson3_ipi_interrupt(struct pt_regs *regs)
if (action & SMP_RESCHEDULE_YOURSELF)
scheduler_ipi();
if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
if (action & SMP_CALL_FUNCTION) {
irq_enter();
generic_smp_call_function_interrupt();
irq_exit();
}
if (action & SMP_ASK_C0COUNT) {
BUG_ON(cpu != 0);

2
arch/mips/mti-malta/malta-int.c
View File

@ -222,7 +222,7 @@ static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
{
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}

2
arch/mips/netlogic/common/smp.c
View File

@ -86,7 +86,7 @@ void nlm_smp_function_ipi_handler(unsigned int irq, struct irq_desc *desc)
{
clear_c0_eimr(irq);
ack_c0_eirr(irq);
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
set_c0_eimr(irq);
}

2
arch/mips/paravirt/paravirt-smp.c
View File

@ -114,7 +114,7 @@ static irqreturn_t paravirt_reched_interrupt(int irq, void *dev_id)
static irqreturn_t paravirt_function_interrupt(int irq, void *dev_id)
{
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}

2
arch/mips/pmcs-msp71xx/msp_smp.c
View File

@ -44,7 +44,7 @@ static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
{
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}

8
arch/mips/sgi-ip27/ip27-irq.c
View File

@ -107,10 +107,14 @@ static void ip27_do_irq_mask0(void)
scheduler_ipi();
} else if (pend0 & (1UL << CPU_CALL_A_IRQ)) {
LOCAL_HUB_CLR_INTR(CPU_CALL_A_IRQ);
smp_call_function_interrupt();
irq_enter();
generic_smp_call_function_interrupt();
irq_exit();
} else if (pend0 & (1UL << CPU_CALL_B_IRQ)) {
LOCAL_HUB_CLR_INTR(CPU_CALL_B_IRQ);
smp_call_function_interrupt();
irq_enter();
generic_smp_call_function_interrupt();
irq_exit();
} else
#endif
{

9
arch/mips/sibyte/bcm1480/smp.c
View File

@ -29,8 +29,6 @@
#include <asm/sibyte/bcm1480_regs.h>
#include <asm/sibyte/bcm1480_int.h>
extern void smp_call_function_interrupt(void);
/*
* These are routines for dealing with the bcm1480 smp capabilities
* independent of board/firmware
@ -184,6 +182,9 @@ void bcm1480_mailbox_interrupt(void)
if (action & SMP_RESCHEDULE_YOURSELF)
scheduler_ipi();
if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
if (action & SMP_CALL_FUNCTION) {
irq_enter();
generic_smp_call_function_interrupt();
irq_exit();
}
}

7
arch/mips/sibyte/sb1250/smp.c
View File

@ -172,6 +172,9 @@ void sb1250_mailbox_interrupt(void)
if (action & SMP_RESCHEDULE_YOURSELF)
scheduler_ipi();
if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
if (action & SMP_CALL_FUNCTION) {
irq_enter();
generic_smp_call_function_interrupt();
irq_exit();
}
}

2
drivers/irqchip/irq-mips-gic.c
View File

@ -538,7 +538,7 @@ static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
{
smp_call_function_interrupt();
generic_smp_call_function_interrupt();
return IRQ_HANDLED;
}