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Message-ID: <20090331122557.GA12975@elte.hu>
Date: Tue, 31 Mar 2009 14:25:57 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
Jens Axboe <jens.axboe@...cle.com>,
Nick Piggin <npiggin@...e.de>
Cc: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Thomas Gleixner <tglx@...utronix.de>
Subject: [GIT PULL] IPI updates for v2.6.30
Linus,
Please pull the latest ipi-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git ipi-for-linus
Highlights:
- Removal of the kmalloc() from smp_call_function*() and the
resulting simplification and refactoring, as discussed in
great detail at:
http://lkml.org/lkml/2009/2/16/217
Known risks:
- The removal of the kmalloc() might in theory affect performance
on large SMP systems:
8969a5e: generic-ipi: remove kmalloc()
There are no known regressions.
Thanks,
Ingo
------------------>
Heiko Carstens (1):
s390: remove arch specific smp_send_stop()
Ingo Molnar (5):
generic-ipi: cleanups
generic-ipi: eliminate WARN_ON()s during oops/panic
panic: decrease oops_in_progress only after having done the panic
panic, smp: provide smp_send_stop() wrapper on UP too
panic: clean up kernel/panic.c
Nick Piggin (1):
generic IPI: simplify barriers and locking
Peter Zijlstra (2):
generic-ipi: remove kmalloc()
generic-ipi: remove CSD_FLAG_WAIT
arch/s390/include/asm/smp.h | 6 -
block/blk-softirq.c | 2 +-
include/linux/smp.h | 7 +-
kernel/panic.c | 115 ++++++------
kernel/sched.c | 2 +-
kernel/smp.c | 432 +++++++++++++++++++++++--------------------
kernel/softirq.c | 2 +-
7 files changed, 304 insertions(+), 262 deletions(-)
diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index 2009158..72137bc 100644
--- a/arch/s390/include/asm/smp.h
+++ b/arch/s390/include/asm/smp.h
@@ -92,12 +92,6 @@ extern void arch_send_call_function_ipi(cpumask_t mask);
#endif
#ifndef CONFIG_SMP
-static inline void smp_send_stop(void)
-{
- /* Disable all interrupts/machine checks */
- __load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
-}
-
#define hard_smp_processor_id() 0
#define smp_cpu_not_running(cpu) 1
#endif
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index ce0efc6..ee9c216 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -64,7 +64,7 @@ static int raise_blk_irq(int cpu, struct request *rq)
data->info = rq;
data->flags = 0;
- __smp_call_function_single(cpu, data);
+ __smp_call_function_single(cpu, data, 0);
return 0;
}
diff --git a/include/linux/smp.h b/include/linux/smp.h
index bbacb7b..a69db82 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -38,7 +38,7 @@ int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
/*
* main cross-CPU interfaces, handles INIT, TLB flush, STOP, etc.
* (defined in asm header):
- */
+ */
/*
* stops all CPUs but the current one:
@@ -82,7 +82,8 @@ smp_call_function_mask(cpumask_t mask, void(*func)(void *info), void *info,
return 0;
}
-void __smp_call_function_single(int cpuid, struct call_single_data *data);
+void __smp_call_function_single(int cpuid, struct call_single_data *data,
+ int wait);
/*
* Generic and arch helpers
@@ -121,6 +122,8 @@ extern unsigned int setup_max_cpus;
#else /* !SMP */
+static inline void smp_send_stop(void) { }
+
/*
* These macros fold the SMP functionality into a single CPU system
*/
diff --git a/kernel/panic.c b/kernel/panic.c
index 32fe4ef..3fd8c5b 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -8,19 +8,19 @@
* This function is used through-out the kernel (including mm and fs)
* to indicate a major problem.
*/
+#include <linux/debug_locks.h>
+#include <linux/interrupt.h>
+#include <linux/kallsyms.h>
+#include <linux/notifier.h>
#include <linux/module.h>
-#include <linux/sched.h>
-#include <linux/delay.h>
+#include <linux/random.h>
#include <linux/reboot.h>
-#include <linux/notifier.h>
-#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/kexec.h>
+#include <linux/sched.h>
#include <linux/sysrq.h>
-#include <linux/interrupt.h>
+#include <linux/init.h>
#include <linux/nmi.h>
-#include <linux/kexec.h>
-#include <linux/debug_locks.h>
-#include <linux/random.h>
-#include <linux/kallsyms.h>
#include <linux/dmi.h>
int panic_on_oops;
@@ -52,19 +52,15 @@ EXPORT_SYMBOL(panic_blink);
*
* This function never returns.
*/
-
NORET_TYPE void panic(const char * fmt, ...)
{
- long i;
static char buf[1024];
va_list args;
-#if defined(CONFIG_S390)
- unsigned long caller = (unsigned long) __builtin_return_address(0);
-#endif
+ long i;
/*
- * It's possible to come here directly from a panic-assertion and not
- * have preempt disabled. Some functions called from here want
+ * It's possible to come here directly from a panic-assertion and
+ * not have preempt disabled. Some functions called from here want
* preempt to be disabled. No point enabling it later though...
*/
preempt_disable();
@@ -77,7 +73,6 @@ NORET_TYPE void panic(const char * fmt, ...)
#ifdef CONFIG_DEBUG_BUGVERBOSE
dump_stack();
#endif
- bust_spinlocks(0);
/*
* If we have crashed and we have a crash kernel loaded let it handle
@@ -86,14 +81,12 @@ NORET_TYPE void panic(const char * fmt, ...)
*/
crash_kexec(NULL);
-#ifdef CONFIG_SMP
/*
* Note smp_send_stop is the usual smp shutdown function, which
* unfortunately means it may not be hardened to work in a panic
* situation.
*/
smp_send_stop();
-#endif
atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
@@ -102,19 +95,21 @@ NORET_TYPE void panic(const char * fmt, ...)
if (panic_timeout > 0) {
/*
- * Delay timeout seconds before rebooting the machine.
- * We can't use the "normal" timers since we just panicked..
- */
- printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
+ * Delay timeout seconds before rebooting the machine.
+ * We can't use the "normal" timers since we just panicked.
+ */
+ printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
+
for (i = 0; i < panic_timeout*1000; ) {
touch_nmi_watchdog();
i += panic_blink(i);
mdelay(1);
i++;
}
- /* This will not be a clean reboot, with everything
- * shutting down. But if there is a chance of
- * rebooting the system it will be rebooted.
+ /*
+ * This will not be a clean reboot, with everything
+ * shutting down. But if there is a chance of
+ * rebooting the system it will be rebooted.
*/
emergency_restart();
}
@@ -127,38 +122,44 @@ NORET_TYPE void panic(const char * fmt, ...)
}
#endif
#if defined(CONFIG_S390)
- disabled_wait(caller);
+ {
+ unsigned long caller;
+
+ caller = (unsigned long)__builtin_return_address(0);
+ disabled_wait(caller);
+ }
#endif
local_irq_enable();
- for (i = 0;;) {
+ for (i = 0; ; ) {
touch_softlockup_watchdog();
i += panic_blink(i);
mdelay(1);
i++;
}
+ bust_spinlocks(0);
}
EXPORT_SYMBOL(panic);
struct tnt {
- u8 bit;
- char true;
- char false;
+ u8 bit;
+ char true;
+ char false;
};
static const struct tnt tnts[] = {
- { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
- { TAINT_FORCED_MODULE, 'F', ' ' },
- { TAINT_UNSAFE_SMP, 'S', ' ' },
- { TAINT_FORCED_RMMOD, 'R', ' ' },
- { TAINT_MACHINE_CHECK, 'M', ' ' },
- { TAINT_BAD_PAGE, 'B', ' ' },
- { TAINT_USER, 'U', ' ' },
- { TAINT_DIE, 'D', ' ' },
- { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
- { TAINT_WARN, 'W', ' ' },
- { TAINT_CRAP, 'C', ' ' },
+ { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
+ { TAINT_FORCED_MODULE, 'F', ' ' },
+ { TAINT_UNSAFE_SMP, 'S', ' ' },
+ { TAINT_FORCED_RMMOD, 'R', ' ' },
+ { TAINT_MACHINE_CHECK, 'M', ' ' },
+ { TAINT_BAD_PAGE, 'B', ' ' },
+ { TAINT_USER, 'U', ' ' },
+ { TAINT_DIE, 'D', ' ' },
+ { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
+ { TAINT_WARN, 'W', ' ' },
+ { TAINT_CRAP, 'C', ' ' },
};
/**
@@ -195,7 +196,8 @@ const char *print_tainted(void)
*s = 0;
} else
snprintf(buf, sizeof(buf), "Not tainted");
- return(buf);
+
+ return buf;
}
int test_taint(unsigned flag)
@@ -211,7 +213,8 @@ unsigned long get_taint(void)
void add_taint(unsigned flag)
{
- debug_locks = 0; /* can't trust the integrity of the kernel anymore */
+ /* can't trust the integrity of the kernel anymore: */
+ debug_locks = 0;
set_bit(flag, &tainted_mask);
}
EXPORT_SYMBOL(add_taint);
@@ -266,8 +269,8 @@ static void do_oops_enter_exit(void)
}
/*
- * Return true if the calling CPU is allowed to print oops-related info. This
- * is a bit racy..
+ * Return true if the calling CPU is allowed to print oops-related info.
+ * This is a bit racy..
*/
int oops_may_print(void)
{
@@ -276,20 +279,22 @@ int oops_may_print(void)
/*
* Called when the architecture enters its oops handler, before it prints
- * anything. If this is the first CPU to oops, and it's oopsing the first time
- * then let it proceed.
+ * anything. If this is the first CPU to oops, and it's oopsing the first
+ * time then let it proceed.
*
- * This is all enabled by the pause_on_oops kernel boot option. We do all this
- * to ensure that oopses don't scroll off the screen. It has the side-effect
- * of preventing later-oopsing CPUs from mucking up the display, too.
+ * This is all enabled by the pause_on_oops kernel boot option. We do all
+ * this to ensure that oopses don't scroll off the screen. It has the
+ * side-effect of preventing later-oopsing CPUs from mucking up the display,
+ * too.
*
- * It turns out that the CPU which is allowed to print ends up pausing for the
- * right duration, whereas all the other CPUs pause for twice as long: once in
- * oops_enter(), once in oops_exit().
+ * It turns out that the CPU which is allowed to print ends up pausing for
+ * the right duration, whereas all the other CPUs pause for twice as long:
+ * once in oops_enter(), once in oops_exit().
*/
void oops_enter(void)
{
- debug_locks_off(); /* can't trust the integrity of the kernel anymore */
+ /* can't trust the integrity of the kernel anymore: */
+ debug_locks_off();
do_oops_enter_exit();
}
diff --git a/kernel/sched.c b/kernel/sched.c
index 196d48b..518ffe5 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1110,7 +1110,7 @@ static void hrtick_start(struct rq *rq, u64 delay)
if (rq == this_rq()) {
hrtimer_restart(timer);
} else if (!rq->hrtick_csd_pending) {
- __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd);
+ __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
rq->hrtick_csd_pending = 1;
}
}
diff --git a/kernel/smp.c b/kernel/smp.c
index bbedbb7..858baac 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -2,40 +2,82 @@
* Generic helpers for smp ipi calls
*
* (C) Jens Axboe <jens.axboe@...cle.com> 2008
- *
*/
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/percpu.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
#include <linux/smp.h>
+#include <linux/cpu.h>
static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
-static LIST_HEAD(call_function_queue);
-__cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);
+
+static struct {
+ struct list_head queue;
+ spinlock_t lock;
+} call_function __cacheline_aligned_in_smp =
+ {
+ .queue = LIST_HEAD_INIT(call_function.queue),
+ .lock = __SPIN_LOCK_UNLOCKED(call_function.lock),
+ };
enum {
- CSD_FLAG_WAIT = 0x01,
- CSD_FLAG_ALLOC = 0x02,
- CSD_FLAG_LOCK = 0x04,
+ CSD_FLAG_LOCK = 0x01,
};
struct call_function_data {
- struct call_single_data csd;
- spinlock_t lock;
- unsigned int refs;
- struct rcu_head rcu_head;
- unsigned long cpumask_bits[];
+ struct call_single_data csd;
+ spinlock_t lock;
+ unsigned int refs;
+ cpumask_var_t cpumask;
};
struct call_single_queue {
- struct list_head list;
- spinlock_t lock;
+ struct list_head list;
+ spinlock_t lock;
+};
+
+static DEFINE_PER_CPU(struct call_function_data, cfd_data) = {
+ .lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock),
+};
+
+static int
+hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+ long cpu = (long)hcpu;
+ struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ if (!alloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
+ cpu_to_node(cpu)))
+ return NOTIFY_BAD;
+ break;
+
+#ifdef CONFIG_CPU_HOTPLUG
+ case CPU_UP_CANCELED:
+ case CPU_UP_CANCELED_FROZEN:
+
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ free_cpumask_var(cfd->cpumask);
+ break;
+#endif
+ };
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
+ .notifier_call = hotplug_cfd,
};
static int __cpuinit init_call_single_data(void)
{
+ void *cpu = (void *)(long)smp_processor_id();
int i;
for_each_possible_cpu(i) {
@@ -44,29 +86,63 @@ static int __cpuinit init_call_single_data(void)
spin_lock_init(&q->lock);
INIT_LIST_HEAD(&q->list);
}
+
+ hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
+ register_cpu_notifier(&hotplug_cfd_notifier);
+
return 0;
}
early_initcall(init_call_single_data);
-static void csd_flag_wait(struct call_single_data *data)
+/*
+ * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
+ *
+ * For non-synchronous ipi calls the csd can still be in use by the
+ * previous function call. For multi-cpu calls its even more interesting
+ * as we'll have to ensure no other cpu is observing our csd.
+ */
+static void csd_lock_wait(struct call_single_data *data)
{
- /* Wait for response */
- do {
- if (!(data->flags & CSD_FLAG_WAIT))
- break;
+ while (data->flags & CSD_FLAG_LOCK)
cpu_relax();
- } while (1);
+}
+
+static void csd_lock(struct call_single_data *data)
+{
+ csd_lock_wait(data);
+ data->flags = CSD_FLAG_LOCK;
+
+ /*
+ * prevent CPU from reordering the above assignment
+ * to ->flags with any subsequent assignments to other
+ * fields of the specified call_single_data structure:
+ */
+ smp_mb();
+}
+
+static void csd_unlock(struct call_single_data *data)
+{
+ WARN_ON(!(data->flags & CSD_FLAG_LOCK));
+
+ /*
+ * ensure we're all done before releasing data:
+ */
+ smp_mb();
+
+ data->flags &= ~CSD_FLAG_LOCK;
}
/*
- * Insert a previously allocated call_single_data element for execution
- * on the given CPU. data must already have ->func, ->info, and ->flags set.
+ * Insert a previously allocated call_single_data element
+ * for execution on the given CPU. data must already have
+ * ->func, ->info, and ->flags set.
*/
-static void generic_exec_single(int cpu, struct call_single_data *data)
+static
+void generic_exec_single(int cpu, struct call_single_data *data, int wait)
{
struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
- int wait = data->flags & CSD_FLAG_WAIT, ipi;
unsigned long flags;
+ int ipi;
spin_lock_irqsave(&dst->lock, flags);
ipi = list_empty(&dst->list);
@@ -74,24 +150,21 @@ static void generic_exec_single(int cpu, struct call_single_data *data)
spin_unlock_irqrestore(&dst->lock, flags);
/*
- * Make the list addition visible before sending the ipi.
+ * The list addition should be visible before sending the IPI
+ * handler locks the list to pull the entry off it because of
+ * normal cache coherency rules implied by spinlocks.
+ *
+ * If IPIs can go out of order to the cache coherency protocol
+ * in an architecture, sufficient synchronisation should be added
+ * to arch code to make it appear to obey cache coherency WRT
+ * locking and barrier primitives. Generic code isn't really
+ * equipped to do the right thing...
*/
- smp_mb();
-
if (ipi)
arch_send_call_function_single_ipi(cpu);
if (wait)
- csd_flag_wait(data);
-}
-
-static void rcu_free_call_data(struct rcu_head *head)
-{
- struct call_function_data *data;
-
- data = container_of(head, struct call_function_data, rcu_head);
-
- kfree(data);
+ csd_lock_wait(data);
}
/*
@@ -104,99 +177,83 @@ void generic_smp_call_function_interrupt(void)
int cpu = get_cpu();
/*
- * It's ok to use list_for_each_rcu() here even though we may delete
- * 'pos', since list_del_rcu() doesn't clear ->next
+ * Ensure entry is visible on call_function_queue after we have
+ * entered the IPI. See comment in smp_call_function_many.
+ * If we don't have this, then we may miss an entry on the list
+ * and never get another IPI to process it.
+ */
+ smp_mb();
+
+ /*
+ * It's ok to use list_for_each_rcu() here even though we may
+ * delete 'pos', since list_del_rcu() doesn't clear ->next
*/
- rcu_read_lock();
- list_for_each_entry_rcu(data, &call_function_queue, csd.list) {
+ list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
int refs;
- if (!cpumask_test_cpu(cpu, to_cpumask(data->cpumask_bits)))
+ spin_lock(&data->lock);
+ if (!cpumask_test_cpu(cpu, data->cpumask)) {
+ spin_unlock(&data->lock);
continue;
+ }
+ cpumask_clear_cpu(cpu, data->cpumask);
+ spin_unlock(&data->lock);
data->csd.func(data->csd.info);
spin_lock(&data->lock);
- cpumask_clear_cpu(cpu, to_cpumask(data->cpumask_bits));
WARN_ON(data->refs == 0);
- data->refs--;
- refs = data->refs;
+ refs = --data->refs;
+ if (!refs) {
+ spin_lock(&call_function.lock);
+ list_del_rcu(&data->csd.list);
+ spin_unlock(&call_function.lock);
+ }
spin_unlock(&data->lock);
if (refs)
continue;
- spin_lock(&call_function_lock);
- list_del_rcu(&data->csd.list);
- spin_unlock(&call_function_lock);
-
- if (data->csd.flags & CSD_FLAG_WAIT) {
- /*
- * serialize stores to data with the flag clear
- * and wakeup
- */
- smp_wmb();
- data->csd.flags &= ~CSD_FLAG_WAIT;
- }
- if (data->csd.flags & CSD_FLAG_ALLOC)
- call_rcu(&data->rcu_head, rcu_free_call_data);
+ csd_unlock(&data->csd);
}
- rcu_read_unlock();
put_cpu();
}
/*
- * Invoked by arch to handle an IPI for call function single. Must be called
- * from the arch with interrupts disabled.
+ * Invoked by arch to handle an IPI for call function single. Must be
+ * called from the arch with interrupts disabled.
*/
void generic_smp_call_function_single_interrupt(void)
{
struct call_single_queue *q = &__get_cpu_var(call_single_queue);
+ unsigned int data_flags;
LIST_HEAD(list);
- /*
- * Need to see other stores to list head for checking whether
- * list is empty without holding q->lock
- */
- smp_read_barrier_depends();
- while (!list_empty(&q->list)) {
- unsigned int data_flags;
-
- spin_lock(&q->lock);
- list_replace_init(&q->list, &list);
- spin_unlock(&q->lock);
-
- while (!list_empty(&list)) {
- struct call_single_data *data;
-
- data = list_entry(list.next, struct call_single_data,
- list);
- list_del(&data->list);
-
- /*
- * 'data' can be invalid after this call if
- * flags == 0 (when called through
- * generic_exec_single(), so save them away before
- * making the call.
- */
- data_flags = data->flags;
-
- data->func(data->info);
-
- if (data_flags & CSD_FLAG_WAIT) {
- smp_wmb();
- data->flags &= ~CSD_FLAG_WAIT;
- } else if (data_flags & CSD_FLAG_LOCK) {
- smp_wmb();
- data->flags &= ~CSD_FLAG_LOCK;
- } else if (data_flags & CSD_FLAG_ALLOC)
- kfree(data);
- }
+ spin_lock(&q->lock);
+ list_replace_init(&q->list, &list);
+ spin_unlock(&q->lock);
+
+ while (!list_empty(&list)) {
+ struct call_single_data *data;
+
+ data = list_entry(list.next, struct call_single_data, list);
+ list_del(&data->list);
+
+ /*
+ * 'data' can be invalid after this call if flags == 0
+ * (when called through generic_exec_single()),
+ * so save them away before making the call:
+ */
+ data_flags = data->flags;
+
+ data->func(data->info);
+
/*
- * See comment on outer loop
+ * Unlocked CSDs are valid through generic_exec_single():
*/
- smp_read_barrier_depends();
+ if (data_flags & CSD_FLAG_LOCK)
+ csd_unlock(data);
}
}
@@ -215,65 +272,45 @@ static DEFINE_PER_CPU(struct call_single_data, csd_data);
int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
int wait)
{
- struct call_single_data d;
+ struct call_single_data d = {
+ .flags = 0,
+ };
unsigned long flags;
- /* prevent preemption and reschedule on another processor,
- as well as CPU removal */
- int me = get_cpu();
+ int this_cpu;
int err = 0;
+ /*
+ * prevent preemption and reschedule on another processor,
+ * as well as CPU removal
+ */
+ this_cpu = get_cpu();
+
/* Can deadlock when called with interrupts disabled */
- WARN_ON(irqs_disabled());
+ WARN_ON_ONCE(irqs_disabled() && !oops_in_progress);
- if (cpu == me) {
+ if (cpu == this_cpu) {
local_irq_save(flags);
func(info);
local_irq_restore(flags);
- } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
- struct call_single_data *data;
+ } else {
+ if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
+ struct call_single_data *data = &d;
+
+ if (!wait)
+ data = &__get_cpu_var(csd_data);
- if (!wait) {
- /*
- * We are calling a function on a single CPU
- * and we are not going to wait for it to finish.
- * We first try to allocate the data, but if we
- * fail, we fall back to use a per cpu data to pass
- * the information to that CPU. Since all callers
- * of this code will use the same data, we must
- * synchronize the callers to prevent a new caller
- * from corrupting the data before the callee
- * can access it.
- *
- * The CSD_FLAG_LOCK is used to let us know when
- * the IPI handler is done with the data.
- * The first caller will set it, and the callee
- * will clear it. The next caller must wait for
- * it to clear before we set it again. This
- * will make sure the callee is done with the
- * data before a new caller will use it.
- */
- data = kmalloc(sizeof(*data), GFP_ATOMIC);
- if (data)
- data->flags = CSD_FLAG_ALLOC;
- else {
- data = &per_cpu(csd_data, me);
- while (data->flags & CSD_FLAG_LOCK)
- cpu_relax();
- data->flags = CSD_FLAG_LOCK;
- }
+ csd_lock(data);
+
+ data->func = func;
+ data->info = info;
+ generic_exec_single(cpu, data, wait);
} else {
- data = &d;
- data->flags = CSD_FLAG_WAIT;
+ err = -ENXIO; /* CPU not online */
}
-
- data->func = func;
- data->info = info;
- generic_exec_single(cpu, data);
- } else {
- err = -ENXIO; /* CPU not online */
}
put_cpu();
+
return err;
}
EXPORT_SYMBOL(smp_call_function_single);
@@ -283,23 +320,26 @@ EXPORT_SYMBOL(smp_call_function_single);
* @cpu: The CPU to run on.
* @data: Pre-allocated and setup data structure
*
- * Like smp_call_function_single(), but allow caller to pass in a pre-allocated
- * data structure. Useful for embedding @data inside other structures, for
- * instance.
- *
+ * Like smp_call_function_single(), but allow caller to pass in a
+ * pre-allocated data structure. Useful for embedding @data inside
+ * other structures, for instance.
*/
-void __smp_call_function_single(int cpu, struct call_single_data *data)
+void __smp_call_function_single(int cpu, struct call_single_data *data,
+ int wait)
{
+ csd_lock(data);
+
/* Can deadlock when called with interrupts disabled */
- WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
+ WARN_ON_ONCE(wait && irqs_disabled() && !oops_in_progress);
- generic_exec_single(cpu, data);
+ generic_exec_single(cpu, data, wait);
}
-/* FIXME: Shim for archs using old arch_send_call_function_ipi API. */
+/* Deprecated: shim for archs using old arch_send_call_function_ipi API. */
+
#ifndef arch_send_call_function_ipi_mask
-#define arch_send_call_function_ipi_mask(maskp) \
- arch_send_call_function_ipi(*(maskp))
+# define arch_send_call_function_ipi_mask(maskp) \
+ arch_send_call_function_ipi(*(maskp))
#endif
/**
@@ -307,7 +347,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
* @mask: The set of cpus to run on (only runs on online subset).
* @func: The function to run. This must be fast and non-blocking.
* @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed on other CPUs.
+ * @wait: If true, wait (atomically) until function has completed
+ * on other CPUs.
*
* If @wait is true, then returns once @func has returned. Note that @wait
* will be implicitly turned on in case of allocation failures, since
@@ -318,27 +359,27 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
* must be disabled when calling this function.
*/
void smp_call_function_many(const struct cpumask *mask,
- void (*func)(void *), void *info,
- bool wait)
+ void (*func)(void *), void *info, bool wait)
{
struct call_function_data *data;
unsigned long flags;
- int cpu, next_cpu;
+ int cpu, next_cpu, this_cpu = smp_processor_id();
/* Can deadlock when called with interrupts disabled */
- WARN_ON(irqs_disabled());
+ WARN_ON_ONCE(irqs_disabled() && !oops_in_progress);
- /* So, what's a CPU they want? Ignoring this one. */
+ /* So, what's a CPU they want? Ignoring this one. */
cpu = cpumask_first_and(mask, cpu_online_mask);
- if (cpu == smp_processor_id())
+ if (cpu == this_cpu)
cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+
/* No online cpus? We're done. */
if (cpu >= nr_cpu_ids)
return;
/* Do we have another CPU which isn't us? */
next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
- if (next_cpu == smp_processor_id())
+ if (next_cpu == this_cpu)
next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
/* Fastpath: do that cpu by itself. */
@@ -347,43 +388,40 @@ void smp_call_function_many(const struct cpumask *mask,
return;
}
- data = kmalloc(sizeof(*data) + cpumask_size(), GFP_ATOMIC);
- if (unlikely(!data)) {
- /* Slow path. */
- for_each_online_cpu(cpu) {
- if (cpu == smp_processor_id())
- continue;
- if (cpumask_test_cpu(cpu, mask))
- smp_call_function_single(cpu, func, info, wait);
- }
- return;
- }
+ data = &__get_cpu_var(cfd_data);
+ csd_lock(&data->csd);
- spin_lock_init(&data->lock);
- data->csd.flags = CSD_FLAG_ALLOC;
- if (wait)
- data->csd.flags |= CSD_FLAG_WAIT;
+ spin_lock_irqsave(&data->lock, flags);
data->csd.func = func;
data->csd.info = info;
- cpumask_and(to_cpumask(data->cpumask_bits), mask, cpu_online_mask);
- cpumask_clear_cpu(smp_processor_id(), to_cpumask(data->cpumask_bits));
- data->refs = cpumask_weight(to_cpumask(data->cpumask_bits));
+ cpumask_and(data->cpumask, mask, cpu_online_mask);
+ cpumask_clear_cpu(this_cpu, data->cpumask);
+ data->refs = cpumask_weight(data->cpumask);
- spin_lock_irqsave(&call_function_lock, flags);
- list_add_tail_rcu(&data->csd.list, &call_function_queue);
- spin_unlock_irqrestore(&call_function_lock, flags);
+ spin_lock(&call_function.lock);
+ /*
+ * Place entry at the _HEAD_ of the list, so that any cpu still
+ * observing the entry in generic_smp_call_function_interrupt()
+ * will not miss any other list entries:
+ */
+ list_add_rcu(&data->csd.list, &call_function.queue);
+ spin_unlock(&call_function.lock);
+
+ spin_unlock_irqrestore(&data->lock, flags);
/*
* Make the list addition visible before sending the ipi.
+ * (IPIs must obey or appear to obey normal Linux cache
+ * coherency rules -- see comment in generic_exec_single).
*/
smp_mb();
/* Send a message to all CPUs in the map */
- arch_send_call_function_ipi_mask(to_cpumask(data->cpumask_bits));
+ arch_send_call_function_ipi_mask(data->cpumask);
- /* optionally wait for the CPUs to complete */
+ /* Optionally wait for the CPUs to complete */
if (wait)
- csd_flag_wait(&data->csd);
+ csd_lock_wait(&data->csd);
}
EXPORT_SYMBOL(smp_call_function_many);
@@ -391,7 +429,8 @@ EXPORT_SYMBOL(smp_call_function_many);
* smp_call_function(): Run a function on all other CPUs.
* @func: The function to run. This must be fast and non-blocking.
* @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed on other CPUs.
+ * @wait: If true, wait (atomically) until function has completed
+ * on other CPUs.
*
* Returns 0.
*
@@ -407,26 +446,27 @@ int smp_call_function(void (*func)(void *), void *info, int wait)
preempt_disable();
smp_call_function_many(cpu_online_mask, func, info, wait);
preempt_enable();
+
return 0;
}
EXPORT_SYMBOL(smp_call_function);
void ipi_call_lock(void)
{
- spin_lock(&call_function_lock);
+ spin_lock(&call_function.lock);
}
void ipi_call_unlock(void)
{
- spin_unlock(&call_function_lock);
+ spin_unlock(&call_function.lock);
}
void ipi_call_lock_irq(void)
{
- spin_lock_irq(&call_function_lock);
+ spin_lock_irq(&call_function.lock);
}
void ipi_call_unlock_irq(void)
{
- spin_unlock_irq(&call_function_lock);
+ spin_unlock_irq(&call_function.lock);
}
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 57d3f67..c349a03 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -496,7 +496,7 @@ static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softir
cp->flags = 0;
cp->priv = softirq;
- __smp_call_function_single(cpu, cp);
+ __smp_call_function_single(cpu, cp, 0);
return 0;
}
return 1;
--
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