Techwizz/kernel-fxtec-pro1x
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

generic-ipi: cleanups

Browse source 
Andrew pointed out that there's some small amount of
style rot in kernel/smp.c.

Clean it up.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-02-25 16:52:11 +01:00
parent 6e2756376c
commit 0b13fda1e0
1 changed files with 88 additions and 78 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

166
kernel/smp.c
View file

@ -2,13 +2,12 @@
* Generic helpers for smp ipi calls * Generic helpers for smp ipi calls
* *
* (C) Jens Axboe <jens.axboe@oracle.com> 2008 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
*
*/ */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/rcupdate.h> #include <linux/rcupdate.h>
#include <linux/rculist.h> #include <linux/rculist.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/smp.h> #include <linux/smp.h>
#include <linux/cpu.h> #include <linux/cpu.h>
@ -17,29 +16,30 @@ static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
static struct { static struct {
struct list_head queue; struct list_head queue;
spinlock_t lock; spinlock_t lock;
} call_function __cacheline_aligned_in_smp = { } call_function __cacheline_aligned_in_smp =
.queue = LIST_HEAD_INIT(call_function.queue), {
.lock = __SPIN_LOCK_UNLOCKED(call_function.lock), .queue = LIST_HEAD_INIT(call_function.queue),
}; .lock = __SPIN_LOCK_UNLOCKED(call_function.lock),
};
enum { enum {
CSD_FLAG_LOCK = 0x01, CSD_FLAG_LOCK = 0x01,
}; };
struct call_function_data { struct call_function_data {
struct call_single_data csd; struct call_single_data csd;
spinlock_t lock; spinlock_t lock;
unsigned int refs; unsigned int refs;
cpumask_var_t cpumask; cpumask_var_t cpumask;
}; };
struct call_single_queue { struct call_single_queue {
struct list_head list; struct list_head list;
spinlock_t lock; spinlock_t lock;
}; };
static DEFINE_PER_CPU(struct call_function_data, cfd_data) = { static DEFINE_PER_CPU(struct call_function_data, cfd_data) = {
.lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock), .lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock),
}; };
static int static int
@ -71,7 +71,7 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
} }
static struct notifier_block __cpuinitdata hotplug_cfd_notifier = { static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
.notifier_call = hotplug_cfd, .notifier_call = hotplug_cfd,
}; };
static int __cpuinit init_call_single_data(void) static int __cpuinit init_call_single_data(void)
@ -96,9 +96,9 @@ early_initcall(init_call_single_data);
/* /*
* csd_lock/csd_unlock used to serialize access to per-cpu csd resources * 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 * For non-synchronous ipi calls the csd can still be in use by the
* function call. For multi-cpu calls its even more interesting as we'll have * previous function call. For multi-cpu calls its even more interesting
* to ensure no other cpu is observing our csd. * as we'll have to ensure no other cpu is observing our csd.
*/ */
static void csd_lock_wait(struct call_single_data *data) static void csd_lock_wait(struct call_single_data *data)
{ {
@ -112,27 +112,29 @@ static void csd_lock(struct call_single_data *data)
data->flags = CSD_FLAG_LOCK; data->flags = CSD_FLAG_LOCK;
/* /*
* prevent CPU from reordering the above assignment to ->flags * prevent CPU from reordering the above assignment
* with any subsequent assignments to other fields of the * to ->flags with any subsequent assignments to other
* specified call_single_data structure. * fields of the specified call_single_data structure:
*/ */
smp_mb(); smp_mb();
} }
static void csd_unlock(struct call_single_data *data) static void csd_unlock(struct call_single_data *data)
{ {
WARN_ON(!(data->flags & CSD_FLAG_LOCK)); WARN_ON(!(data->flags & CSD_FLAG_LOCK));
/* /*
* ensure we're all done before releasing data * ensure we're all done before releasing data:
*/ */
smp_mb(); smp_mb();
data->flags &= ~CSD_FLAG_LOCK; data->flags &= ~CSD_FLAG_LOCK;
} }
/* /*
* Insert a previously allocated call_single_data element for execution * Insert a previously allocated call_single_data element
* on the given CPU. data must already have ->func, ->info, and ->flags set. * for execution on the given CPU. data must already have
* ->func, ->info, and ->flags set.
*/ */
static static
void generic_exec_single(int cpu, struct call_single_data *data, int wait) void generic_exec_single(int cpu, struct call_single_data *data, int wait)
@ -154,10 +156,9 @@ void generic_exec_single(int cpu, struct call_single_data *data, int wait)
* If IPIs can go out of order to the cache coherency protocol * If IPIs can go out of order to the cache coherency protocol
* in an architecture, sufficient synchronisation should be added * in an architecture, sufficient synchronisation should be added
* to arch code to make it appear to obey cache coherency WRT * to arch code to make it appear to obey cache coherency WRT
* locking and barrier primitives. Generic code isn't really equipped * locking and barrier primitives. Generic code isn't really
* to do the right thing... * equipped to do the right thing...
*/ */
if (ipi) if (ipi)
arch_send_call_function_single_ipi(cpu); arch_send_call_function_single_ipi(cpu);
@ -183,8 +184,8 @@ void generic_smp_call_function_interrupt(void)
smp_mb(); smp_mb();
/* /*
* It's ok to use list_for_each_rcu() here even though we may delete * It's ok to use list_for_each_rcu() here even though we may
* 'pos', since list_del_rcu() doesn't clear ->next * delete 'pos', since list_del_rcu() doesn't clear ->next
*/ */
list_for_each_entry_rcu(data, &call_function.queue, csd.list) { list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
int refs; int refs;
@ -219,14 +220,14 @@ void generic_smp_call_function_interrupt(void)
} }
/* /*
* Invoked by arch to handle an IPI for call function single. Must be called * Invoked by arch to handle an IPI for call function single. Must be
* from the arch with interrupts disabled. * called from the arch with interrupts disabled.
*/ */
void generic_smp_call_function_single_interrupt(void) void generic_smp_call_function_single_interrupt(void)
{ {
struct call_single_queue *q = &__get_cpu_var(call_single_queue); struct call_single_queue *q = &__get_cpu_var(call_single_queue);
LIST_HEAD(list);
unsigned int data_flags; unsigned int data_flags;
LIST_HEAD(list);
spin_lock(&q->lock); spin_lock(&q->lock);
list_replace_init(&q->list, &list); list_replace_init(&q->list, &list);
@ -235,22 +236,20 @@ void generic_smp_call_function_single_interrupt(void)
while (!list_empty(&list)) { while (!list_empty(&list)) {
struct call_single_data *data; struct call_single_data *data;
data = list_entry(list.next, struct call_single_data, data = list_entry(list.next, struct call_single_data, list);
list);
list_del(&data->list); list_del(&data->list);
/* /*
* 'data' can be invalid after this call if * 'data' can be invalid after this call if flags == 0
* flags == 0 (when called through * (when called through generic_exec_single()),
* generic_exec_single(), so save them away before * so save them away before making the call:
* making the call.
*/ */
data_flags = data->flags; data_flags = data->flags;
data->func(data->info); data->func(data->info);
/* /*
* Unlocked CSDs are valid through generic_exec_single() * Unlocked CSDs are valid through generic_exec_single():
*/ */
if (data_flags & CSD_FLAG_LOCK) if (data_flags & CSD_FLAG_LOCK)
csd_unlock(data); csd_unlock(data);
@ -276,34 +275,41 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
.flags = 0, .flags = 0,
}; };
unsigned long flags; unsigned long flags;
/* prevent preemption and reschedule on another processor, int this_cpu;
as well as CPU removal */
int me = get_cpu();
int err = 0; 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 */ /* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled()); WARN_ON(irqs_disabled());
if (cpu == me) { if (cpu == this_cpu) {
local_irq_save(flags); local_irq_save(flags);
func(info); func(info);
local_irq_restore(flags); local_irq_restore(flags);
} else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
struct call_single_data *data = &d;
if (!wait)
data = &__get_cpu_var(csd_data);
csd_lock(data);
data->func = func;
data->info = info;
generic_exec_single(cpu, data, wait);
} else { } else {
err = -ENXIO; /* CPU not online */ if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
struct call_single_data *data = &d;
if (!wait)
data = &__get_cpu_var(csd_data);
csd_lock(data);
data->func = func;
data->info = info;
generic_exec_single(cpu, data, wait);
} else {
err = -ENXIO; /* CPU not online */
}
} }
put_cpu(); put_cpu();
return err; return err;
} }
EXPORT_SYMBOL(smp_call_function_single); EXPORT_SYMBOL(smp_call_function_single);
@ -313,10 +319,9 @@ EXPORT_SYMBOL(smp_call_function_single);
* @cpu: The CPU to run on. * @cpu: The CPU to run on.
* @data: Pre-allocated and setup data structure * @data: Pre-allocated and setup data structure
* *
* Like smp_call_function_single(), but allow caller to pass in a pre-allocated * Like smp_call_function_single(), but allow caller to pass in a
* data structure. Useful for embedding @data inside other structures, for * pre-allocated data structure. Useful for embedding @data inside
* instance. * 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) int wait)
@ -329,10 +334,11 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
generic_exec_single(cpu, data, wait); 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 #ifndef arch_send_call_function_ipi_mask
#define arch_send_call_function_ipi_mask(maskp) \ # define arch_send_call_function_ipi_mask(maskp) \
arch_send_call_function_ipi(*(maskp)) arch_send_call_function_ipi(*(maskp))
#endif #endif
/** /**
@ -340,7 +346,8 @@ 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). * @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. * @func: The function to run. This must be fast and non-blocking.
* @info: An arbitrary pointer to pass to the function. * @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 * If @wait is true, then returns once @func has returned. Note that @wait
* will be implicitly turned on in case of allocation failures, since * will be implicitly turned on in case of allocation failures, since
@ -351,27 +358,27 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
* must be disabled when calling this function. * must be disabled when calling this function.
*/ */
void smp_call_function_many(const struct cpumask *mask, void smp_call_function_many(const struct cpumask *mask,
void (*func)(void *), void *info, void (*func)(void *), void *info, bool wait)
bool wait)
{ {
struct call_function_data *data; struct call_function_data *data;
unsigned long flags; unsigned long flags;
int cpu, next_cpu, me = smp_processor_id(); int cpu, next_cpu, this_cpu = smp_processor_id();
/* Can deadlock when called with interrupts disabled */ /* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled()); WARN_ON(irqs_disabled());
/* 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); cpu = cpumask_first_and(mask, cpu_online_mask);
if (cpu == me) if (cpu == this_cpu)
cpu = cpumask_next_and(cpu, mask, cpu_online_mask); cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
/* No online cpus? We're done. */ /* No online cpus? We're done. */
if (cpu >= nr_cpu_ids) if (cpu >= nr_cpu_ids)
return; return;
/* Do we have another CPU which isn't us? */ /* Do we have another CPU which isn't us? */
next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
if (next_cpu == me) if (next_cpu == this_cpu)
next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
/* Fastpath: do that cpu by itself. */ /* Fastpath: do that cpu by itself. */
@ -387,30 +394,31 @@ void smp_call_function_many(const struct cpumask *mask,
data->csd.func = func; data->csd.func = func;
data->csd.info = info; data->csd.info = info;
cpumask_and(data->cpumask, mask, cpu_online_mask); cpumask_and(data->cpumask, mask, cpu_online_mask);
cpumask_clear_cpu(me, data->cpumask); cpumask_clear_cpu(this_cpu, data->cpumask);
data->refs = cpumask_weight(data->cpumask); data->refs = cpumask_weight(data->cpumask);
spin_lock(&call_function.lock); spin_lock(&call_function.lock);
/* /*
* Place entry at the _HEAD_ of the list, so that any cpu still * Place entry at the _HEAD_ of the list, so that any cpu still
* observing the entry in generic_smp_call_function_interrupt() will * observing the entry in generic_smp_call_function_interrupt()
* not miss any other list entries. * will not miss any other list entries:
*/ */
list_add_rcu(&data->csd.list, &call_function.queue); list_add_rcu(&data->csd.list, &call_function.queue);
spin_unlock(&call_function.lock); spin_unlock(&call_function.lock);
spin_unlock_irqrestore(&data->lock, flags); spin_unlock_irqrestore(&data->lock, flags);
/* /*
* Make the list addition visible before sending the ipi. * Make the list addition visible before sending the ipi.
* (IPIs must obey or appear to obey normal Linux cache coherency * (IPIs must obey or appear to obey normal Linux cache
* rules -- see comment in generic_exec_single). * coherency rules -- see comment in generic_exec_single).
*/ */
smp_mb(); smp_mb();
/* Send a message to all CPUs in the map */ /* Send a message to all CPUs in the map */
arch_send_call_function_ipi_mask(data->cpumask); arch_send_call_function_ipi_mask(data->cpumask);
/* optionally wait for the CPUs to complete */ /* Optionally wait for the CPUs to complete */
if (wait) if (wait)
csd_lock_wait(&data->csd); csd_lock_wait(&data->csd);
} }
@ -420,7 +428,8 @@ EXPORT_SYMBOL(smp_call_function_many);
* smp_call_function(): Run a function on all other CPUs. * smp_call_function(): Run a function on all other CPUs.
* @func: The function to run. This must be fast and non-blocking. * @func: The function to run. This must be fast and non-blocking.
* @info: An arbitrary pointer to pass to the function. * @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. * Returns 0.
* *
@ -436,6 +445,7 @@ int smp_call_function(void (*func)(void *), void *info, int wait)
preempt_disable(); preempt_disable();
smp_call_function_many(cpu_online_mask, func, info, wait); smp_call_function_many(cpu_online_mask, func, info, wait);
preempt_enable(); preempt_enable();
return 0; return 0;
} }
EXPORT_SYMBOL(smp_call_function); EXPORT_SYMBOL(smp_call_function);