[tip:sched/locking] sched: Provide scheduler_ipi() callback in response to smp_send_reschedule()

From: tip-bot for Peter Zijlstra
Date: Thu Apr 14 2011 - 04:33:38 EST

Commit-ID: 184748cc50b2dceb8287f9fb657eda48ff8fcfe7
Gitweb: http://git.kernel.org/tip/184748cc50b2dceb8287f9fb657eda48ff8fcfe7
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Tue, 5 Apr 2011 17:23:39 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 14 Apr 2011 08:52:32 +0200

sched: Provide scheduler_ipi() callback in response to smp_send_reschedule()

For future rework of try_to_wake_up() we'd like to push part of that
function onto the CPU the task is actually going to run on.

In order to do so we need a generic callback from the existing scheduler IPI.

This patch introduces such a generic callback: scheduler_ipi() and
implements it as a NOP.

BenH notes: PowerPC might use this IPI on offline CPUs under rare conditions!

Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Acked-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Acked-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Acked-by: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
Acked-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Reviewed-by: Frank Rowand <frank.rowand@xxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20110405152728.744338123@xxxxxxxxx
---
arch/alpha/kernel/smp.c | 3 +--
arch/arm/kernel/smp.c | 5 +----
arch/blackfin/mach-common/smp.c | 3 +++
arch/cris/arch-v32/kernel/smp.c | 13 ++++++++-----
arch/ia64/kernel/irq_ia64.c | 2 ++
arch/ia64/xen/irq_xen.c | 10 +++++++++-
arch/m32r/kernel/smp.c | 4 +---
arch/mips/cavium-octeon/smp.c | 2 ++
arch/mips/kernel/smtc.c | 2 +-
arch/mips/mti-malta/malta-int.c | 2 ++
arch/mips/pmc-sierra/yosemite/smp.c | 4 ++++
arch/mips/sgi-ip27/ip27-irq.c | 2 ++
arch/mips/sibyte/bcm1480/smp.c | 7 +++----
arch/mips/sibyte/sb1250/smp.c | 7 +++----
arch/mn10300/kernel/smp.c | 5 +----
arch/parisc/kernel/smp.c | 5 +----
arch/powerpc/kernel/smp.c | 4 ++--
arch/s390/kernel/smp.c | 6 +++---
arch/sh/kernel/smp.c | 2 ++
arch/sparc/kernel/smp_32.c | 4 +++-
arch/sparc/kernel/smp_64.c | 1 +
arch/tile/kernel/smp.c | 6 +-----
arch/um/kernel/smp.c | 2 +-
arch/x86/kernel/smp.c | 5 ++---
arch/x86/xen/smp.c | 5 ++---
include/linux/sched.h | 2 ++
26 files changed, 63 insertions(+), 50 deletions(-)

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 42aa078..5a621c6 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -585,8 +585,7 @@ handle_ipi(struct pt_regs *regs)

switch (which) {
case IPI_RESCHEDULE:
- /* Reschedule callback. Everything to be done
- is done by the interrupt return path. */
+ scheduler_ipi();
break;

case IPI_CALL_FUNC:
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 8fe05ad..7a561eb 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -560,10 +560,7 @@ asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
break;

case IPI_RESCHEDULE:
- /*
- * nothing more to do - eveything is
- * done on the interrupt return path
- */
+ scheduler_ipi();
break;

case IPI_CALL_FUNC:
diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c
index 6e17a26..326bb86 100644
--- a/arch/blackfin/mach-common/smp.c
+++ b/arch/blackfin/mach-common/smp.c
@@ -164,6 +164,9 @@ static irqreturn_t ipi_handler_int1(int irq, void *dev_instance)
while (msg_queue->count) {
msg = &msg_queue->ipi_message[msg_queue->head];
switch (msg->type) {
+ case BFIN_IPI_RESCHEDULE:
+ scheduler_ipi();
+ break;
case BFIN_IPI_CALL_FUNC:
spin_unlock_irqrestore(&msg_queue->lock, flags);
ipi_call_function(cpu, msg);
diff --git a/arch/cris/arch-v32/kernel/smp.c b/arch/cris/arch-v32/kernel/smp.c
index 4c9e3e1..66cc756 100644
--- a/arch/cris/arch-v32/kernel/smp.c
+++ b/arch/cris/arch-v32/kernel/smp.c
@@ -342,15 +342,18 @@ irqreturn_t crisv32_ipi_interrupt(int irq, void *dev_id)

ipi = REG_RD(intr_vect, irq_regs[smp_processor_id()], rw_ipi);

+ if (ipi.vector & IPI_SCHEDULE) {
+ scheduler_ipi();
+ }
if (ipi.vector & IPI_CALL) {
- func(info);
+ func(info);
}
if (ipi.vector & IPI_FLUSH_TLB) {
- if (flush_mm == FLUSH_ALL)
- __flush_tlb_all();
- else if (flush_vma == FLUSH_ALL)
+ if (flush_mm == FLUSH_ALL)
+ __flush_tlb_all();
+ else if (flush_vma == FLUSH_ALL)
__flush_tlb_mm(flush_mm);
- else
+ else
__flush_tlb_page(flush_vma, flush_addr);
}

diff --git a/arch/ia64/kernel/irq_ia64.c b/arch/ia64/kernel/irq_ia64.c
index 5b70474..782c3a35 100644
--- a/arch/ia64/kernel/irq_ia64.c
+++ b/arch/ia64/kernel/irq_ia64.c
@@ -31,6 +31,7 @@
#include <linux/irq.h>
#include <linux/ratelimit.h>
#include <linux/acpi.h>
+#include <linux/sched.h>

#include <asm/delay.h>
#include <asm/intrinsics.h>
@@ -496,6 +497,7 @@ ia64_handle_irq (ia64_vector vector, struct pt_regs *regs)
smp_local_flush_tlb();
kstat_incr_irqs_this_cpu(irq, desc);
} else if (unlikely(IS_RESCHEDULE(vector))) {
+ scheduler_ipi();
kstat_incr_irqs_this_cpu(irq, desc);
} else {
ia64_setreg(_IA64_REG_CR_TPR, vector);
diff --git a/arch/ia64/xen/irq_xen.c b/arch/ia64/xen/irq_xen.c
index 108bb85..b279e14 100644
--- a/arch/ia64/xen/irq_xen.c
+++ b/arch/ia64/xen/irq_xen.c
@@ -92,6 +92,8 @@ static unsigned short saved_irq_cnt;
static int xen_slab_ready;

#ifdef CONFIG_SMP
+#include <linux/sched.h>
+
/* Dummy stub. Though we may check XEN_RESCHEDULE_VECTOR before __do_IRQ,
* it ends up to issue several memory accesses upon percpu data and
* thus adds unnecessary traffic to other paths.
@@ -99,7 +101,13 @@ static int xen_slab_ready;
static irqreturn_t
xen_dummy_handler(int irq, void *dev_id)
{
+ return IRQ_HANDLED;
+}

+static irqreturn_t
+xen_resched_handler(int irq, void *dev_id)
+{
+ scheduler_ipi();
return IRQ_HANDLED;
}

@@ -110,7 +118,7 @@ static struct irqaction xen_ipi_irqaction = {
};

static struct irqaction xen_resched_irqaction = {
- .handler = xen_dummy_handler,
+ .handler = xen_resched_handler,
.flags = IRQF_DISABLED,
.name = "resched"
};
diff --git a/arch/m32r/kernel/smp.c b/arch/m32r/kernel/smp.c
index 31cef20..fc10b39 100644
--- a/arch/m32r/kernel/smp.c
+++ b/arch/m32r/kernel/smp.c
@@ -122,8 +122,6 @@ void smp_send_reschedule(int cpu_id)
*
* Description: This routine executes on CPU which received
* 'RESCHEDULE_IPI'.
- * Rescheduling is processed at the exit of interrupt
- * operation.
*
* Born on Date: 2002.02.05
*
@@ -138,7 +136,7 @@ void smp_send_reschedule(int cpu_id)
*==========================================================================*/
void smp_reschedule_interrupt(void)
{
- /* nothing to do */
+ scheduler_ipi();
}

/*==========================================================================*
diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
index ba78b21..76923ee 100644
--- a/arch/mips/cavium-octeon/smp.c
+++ b/arch/mips/cavium-octeon/smp.c
@@ -44,6 +44,8 @@ static irqreturn_t mailbox_interrupt(int irq, void *dev_id)

if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
+ if (action & SMP_RESCHEDULE_YOURSELF)
+ scheduler_ipi();

/* Check if we've been told to flush the icache */
if (action & SMP_ICACHE_FLUSH)
diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c
index 5a88cc4..cedac46 100644
--- a/arch/mips/kernel/smtc.c
+++ b/arch/mips/kernel/smtc.c
@@ -929,7 +929,7 @@ static void post_direct_ipi(int cpu, struct smtc_ipi *pipi)

static void ipi_resched_interrupt(void)
{
- /* Return from interrupt should be enough to cause scheduler check */
+ scheduler_ipi();
}

static void ipi_call_interrupt(void)
diff --git a/arch/mips/mti-malta/malta-int.c b/arch/mips/mti-malta/malta-int.c
index 9027061..7d93e6f 100644
--- a/arch/mips/mti-malta/malta-int.c
+++ b/arch/mips/mti-malta/malta-int.c
@@ -309,6 +309,8 @@ static void ipi_call_dispatch(void)

static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
{
+ scheduler_ipi();
+
return IRQ_HANDLED;
}

diff --git a/arch/mips/pmc-sierra/yosemite/smp.c b/arch/mips/pmc-sierra/yosemite/smp.c
index efc9e88..2608752 100644
--- a/arch/mips/pmc-sierra/yosemite/smp.c
+++ b/arch/mips/pmc-sierra/yosemite/smp.c
@@ -55,6 +55,8 @@ void titan_mailbox_irq(void)

if (status & 0x2)
smp_call_function_interrupt();
+ if (status & 0x4)
+ scheduler_ipi();
break;

case 1:
@@ -63,6 +65,8 @@ void titan_mailbox_irq(void)

if (status & 0x2)
smp_call_function_interrupt();
+ if (status & 0x4)
+ scheduler_ipi();
break;
}
}
diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c
index 0a04603..b18b04e 100644
--- a/arch/mips/sgi-ip27/ip27-irq.c
+++ b/arch/mips/sgi-ip27/ip27-irq.c
@@ -147,8 +147,10 @@ static void ip27_do_irq_mask0(void)
#ifdef CONFIG_SMP
if (pend0 & (1UL << CPU_RESCHED_A_IRQ)) {
LOCAL_HUB_CLR_INTR(CPU_RESCHED_A_IRQ);
+ scheduler_ipi();
} else if (pend0 & (1UL << CPU_RESCHED_B_IRQ)) {
LOCAL_HUB_CLR_INTR(CPU_RESCHED_B_IRQ);
+ scheduler_ipi();
} else if (pend0 & (1UL << CPU_CALL_A_IRQ)) {
LOCAL_HUB_CLR_INTR(CPU_CALL_A_IRQ);
smp_call_function_interrupt();
diff --git a/arch/mips/sibyte/bcm1480/smp.c b/arch/mips/sibyte/bcm1480/smp.c
index 47b347c..d667875 100644
--- a/arch/mips/sibyte/bcm1480/smp.c
+++ b/arch/mips/sibyte/bcm1480/smp.c
@@ -20,6 +20,7 @@
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
+#include <linux/sched.h>

#include <asm/mmu_context.h>
#include <asm/io.h>
@@ -189,10 +190,8 @@ void bcm1480_mailbox_interrupt(void)
/* Clear the mailbox to clear the interrupt */
__raw_writeq(((u64)action)<<48, mailbox_0_clear_regs[cpu]);

- /*
- * Nothing to do for SMP_RESCHEDULE_YOURSELF; returning from the
- * interrupt will do the reschedule for us
- */
+ if (action & SMP_RESCHEDULE_YOURSELF)
+ scheduler_ipi();

if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
diff --git a/arch/mips/sibyte/sb1250/smp.c b/arch/mips/sibyte/sb1250/smp.c
index c00a5cb..38e7f6b 100644
--- a/arch/mips/sibyte/sb1250/smp.c
+++ b/arch/mips/sibyte/sb1250/smp.c
@@ -21,6 +21,7 @@
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
+#include <linux/sched.h>

#include <asm/mmu_context.h>
#include <asm/io.h>
@@ -177,10 +178,8 @@ void sb1250_mailbox_interrupt(void)
/* Clear the mailbox to clear the interrupt */
____raw_writeq(((u64)action) << 48, mailbox_clear_regs[cpu]);

- /*
- * Nothing to do for SMP_RESCHEDULE_YOURSELF; returning from the
- * interrupt will do the reschedule for us
- */
+ if (action & SMP_RESCHEDULE_YOURSELF)
+ scheduler_ipi();

if (action & SMP_CALL_FUNCTION)
smp_call_function_interrupt();
diff --git a/arch/mn10300/kernel/smp.c b/arch/mn10300/kernel/smp.c
index 226c826..83fb279 100644
--- a/arch/mn10300/kernel/smp.c
+++ b/arch/mn10300/kernel/smp.c
@@ -494,14 +494,11 @@ void smp_send_stop(void)
* @irq: The interrupt number.
* @dev_id: The device ID.
*
- * We need do nothing here, since the scheduling will be effected on our way
- * back through entry.S.
- *
* Returns IRQ_HANDLED to indicate we handled the interrupt successfully.
*/
static irqreturn_t smp_reschedule_interrupt(int irq, void *dev_id)
{
- /* do nothing */
+ scheduler_ipi();
return IRQ_HANDLED;
}

diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index 69d63d3..828305f 100644
--- a/arch/parisc/kernel/smp.c
+++ b/arch/parisc/kernel/smp.c
@@ -155,10 +155,7 @@ ipi_interrupt(int irq, void *dev_id)

case IPI_RESCHEDULE:
smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
- /*
- * Reschedule callback. Everything to be
- * done is done by the interrupt return path.
- */
+ scheduler_ipi();
break;

case IPI_CALL_FUNC:
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index cbdbb14..9f9c204 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -116,7 +116,7 @@ void smp_message_recv(int msg)
generic_smp_call_function_interrupt();
break;
case PPC_MSG_RESCHEDULE:
- /* we notice need_resched on exit */
+ scheduler_ipi();
break;
case PPC_MSG_CALL_FUNC_SINGLE:
generic_smp_call_function_single_interrupt();
@@ -146,7 +146,7 @@ static irqreturn_t call_function_action(int irq, void *data)

static irqreturn_t reschedule_action(int irq, void *data)
{
- /* we just need the return path side effect of checking need_resched */
+ scheduler_ipi();
return IRQ_HANDLED;
}

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 63a97db..63c7d9f 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -165,12 +165,12 @@ static void do_ext_call_interrupt(unsigned int ext_int_code,
kstat_cpu(smp_processor_id()).irqs[EXTINT_IPI]++;
/*
* handle bit signal external calls
- *
- * For the ec_schedule signal we have to do nothing. All the work
- * is done automatically when we return from the interrupt.
*/
bits = xchg(&S390_lowcore.ext_call_fast, 0);

+ if (test_bit(ec_schedule, &bits))
+ scheduler_ipi();
+
if (test_bit(ec_call_function, &bits))
generic_smp_call_function_interrupt();

diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index 509b36b..6207561 100644
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -20,6 +20,7 @@
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/interrupt.h>
+#include <linux/sched.h>
#include <asm/atomic.h>
#include <asm/processor.h>
#include <asm/system.h>
@@ -323,6 +324,7 @@ void smp_message_recv(unsigned int msg)
generic_smp_call_function_interrupt();
break;
case SMP_MSG_RESCHEDULE:
+ scheduler_ipi();
break;
case SMP_MSG_FUNCTION_SINGLE:
generic_smp_call_function_single_interrupt();
diff --git a/arch/sparc/kernel/smp_32.c b/arch/sparc/kernel/smp_32.c
index 91c10fb..f95690c 100644
--- a/arch/sparc/kernel/smp_32.c
+++ b/arch/sparc/kernel/smp_32.c
@@ -125,7 +125,9 @@ struct linux_prom_registers smp_penguin_ctable __cpuinitdata = { 0 };

void smp_send_reschedule(int cpu)
{
- /* See sparc64 */
+ /*
+ * XXX missing reschedule IPI, see scheduler_ipi()
+ */
}

void smp_send_stop(void)
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 3e94a8c..9478da7 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1368,6 +1368,7 @@ void smp_send_reschedule(int cpu)
void __irq_entry smp_receive_signal_client(int irq, struct pt_regs *regs)
{
clear_softint(1 << irq);
+ scheduler_ipi();
}

/* This is a nop because we capture all other cpus
diff --git a/arch/tile/kernel/smp.c b/arch/tile/kernel/smp.c
index a429310..c52224d 100644
--- a/arch/tile/kernel/smp.c
+++ b/arch/tile/kernel/smp.c
@@ -189,12 +189,8 @@ void flush_icache_range(unsigned long start, unsigned long end)
/* Called when smp_send_reschedule() triggers IRQ_RESCHEDULE. */
static irqreturn_t handle_reschedule_ipi(int irq, void *token)
{
- /*
- * Nothing to do here; when we return from interrupt, the
- * rescheduling will occur there. But do bump the interrupt
- * profiler count in the meantime.
- */
__get_cpu_var(irq_stat).irq_resched_count++;
+ scheduler_ipi();

return IRQ_HANDLED;
}
diff --git a/arch/um/kernel/smp.c b/arch/um/kernel/smp.c
index 106bf27..eefb107 100644
--- a/arch/um/kernel/smp.c
+++ b/arch/um/kernel/smp.c
@@ -173,7 +173,7 @@ void IPI_handler(int cpu)
break;

case 'R':
- set_tsk_need_resched(current);
+ scheduler_ipi();
break;

case 'S':
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 513deac..013e7eb 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -194,14 +194,13 @@ static void native_stop_other_cpus(int wait)
}

/*
- * Reschedule call back. Nothing to do,
- * all the work is done automatically when
- * we return from the interrupt.
+ * Reschedule call back.
*/
void smp_reschedule_interrupt(struct pt_regs *regs)
{
ack_APIC_irq();
inc_irq_stat(irq_resched_count);
+ scheduler_ipi();
/*
* KVM uses this interrupt to force a cpu out of guest mode
*/
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 3061244..762b46a 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -46,13 +46,12 @@ static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id);

/*
- * Reschedule call back. Nothing to do,
- * all the work is done automatically when
- * we return from the interrupt.
+ * Reschedule call back.
*/
static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
{
inc_irq_stat(irq_resched_count);
+ scheduler_ipi();

return IRQ_HANDLED;
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4ec2c02..758e27a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2189,8 +2189,10 @@ extern void set_task_comm(struct task_struct *tsk, char *from);
extern char *get_task_comm(char *to, struct task_struct *tsk);

#ifdef CONFIG_SMP
+static inline void scheduler_ipi(void) { }
extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
#else
+static inline void scheduler_ipi(void) { }
static inline unsigned long wait_task_inactive(struct task_struct *p,
long match_state)
{
--
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