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generic-ipi: cleanups
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
parent
6e2756376c
commit
0b13fda1e0
1 changed files with 88 additions and 78 deletions
116
kernel/smp.c
116
kernel/smp.c
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@ -2,13 +2,12 @@
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* Generic helpers for smp ipi calls
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*
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* (C) Jens Axboe <jens.axboe@oracle.com> 2008
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*
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/percpu.h>
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#include <linux/rcupdate.h>
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#include <linux/rculist.h>
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#include <linux/module.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/cpu.h>
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@ -17,7 +16,8 @@ static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
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static struct {
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struct list_head queue;
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spinlock_t lock;
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} call_function __cacheline_aligned_in_smp = {
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} call_function __cacheline_aligned_in_smp =
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{
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.queue = LIST_HEAD_INIT(call_function.queue),
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.lock = __SPIN_LOCK_UNLOCKED(call_function.lock),
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};
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@ -96,9 +96,9 @@ early_initcall(init_call_single_data);
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/*
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* csd_lock/csd_unlock used to serialize access to per-cpu csd resources
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*
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* For non-synchronous ipi calls the csd can still be in use by the previous
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* function call. For multi-cpu calls its even more interesting as we'll have
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* to ensure no other cpu is observing our csd.
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* For non-synchronous ipi calls the csd can still be in use by the
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* previous function call. For multi-cpu calls its even more interesting
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* as we'll have to ensure no other cpu is observing our csd.
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*/
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static void csd_lock_wait(struct call_single_data *data)
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{
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@ -112,27 +112,29 @@ static void csd_lock(struct call_single_data *data)
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data->flags = CSD_FLAG_LOCK;
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/*
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* prevent CPU from reordering the above assignment to ->flags
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* with any subsequent assignments to other fields of the
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* specified call_single_data structure.
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* prevent CPU from reordering the above assignment
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* to ->flags with any subsequent assignments to other
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* fields of the specified call_single_data structure:
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*/
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smp_mb();
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}
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static void csd_unlock(struct call_single_data *data)
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{
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WARN_ON(!(data->flags & CSD_FLAG_LOCK));
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/*
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* ensure we're all done before releasing data
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* ensure we're all done before releasing data:
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*/
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smp_mb();
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data->flags &= ~CSD_FLAG_LOCK;
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}
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/*
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* Insert a previously allocated call_single_data element for execution
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* on the given CPU. data must already have ->func, ->info, and ->flags set.
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* Insert a previously allocated call_single_data element
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* for execution on the given CPU. data must already have
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* ->func, ->info, and ->flags set.
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*/
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static
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void generic_exec_single(int cpu, struct call_single_data *data, int wait)
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@ -154,10 +156,9 @@ void generic_exec_single(int cpu, struct call_single_data *data, int wait)
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* If IPIs can go out of order to the cache coherency protocol
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* in an architecture, sufficient synchronisation should be added
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* to arch code to make it appear to obey cache coherency WRT
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* locking and barrier primitives. Generic code isn't really equipped
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* to do the right thing...
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* locking and barrier primitives. Generic code isn't really
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* equipped to do the right thing...
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*/
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if (ipi)
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arch_send_call_function_single_ipi(cpu);
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@ -183,8 +184,8 @@ void generic_smp_call_function_interrupt(void)
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smp_mb();
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/*
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* It's ok to use list_for_each_rcu() here even though we may delete
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* 'pos', since list_del_rcu() doesn't clear ->next
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* It's ok to use list_for_each_rcu() here even though we may
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* delete 'pos', since list_del_rcu() doesn't clear ->next
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*/
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list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
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int refs;
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@ -219,14 +220,14 @@ void generic_smp_call_function_interrupt(void)
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}
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/*
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* Invoked by arch to handle an IPI for call function single. Must be called
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* from the arch with interrupts disabled.
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* Invoked by arch to handle an IPI for call function single. Must be
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* called from the arch with interrupts disabled.
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*/
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void generic_smp_call_function_single_interrupt(void)
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{
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struct call_single_queue *q = &__get_cpu_var(call_single_queue);
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LIST_HEAD(list);
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unsigned int data_flags;
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LIST_HEAD(list);
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spin_lock(&q->lock);
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list_replace_init(&q->list, &list);
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@ -235,22 +236,20 @@ void generic_smp_call_function_single_interrupt(void)
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while (!list_empty(&list)) {
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struct call_single_data *data;
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data = list_entry(list.next, struct call_single_data,
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list);
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data = list_entry(list.next, struct call_single_data, list);
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list_del(&data->list);
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/*
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* 'data' can be invalid after this call if
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* flags == 0 (when called through
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* generic_exec_single(), so save them away before
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* making the call.
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* 'data' can be invalid after this call if flags == 0
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* (when called through generic_exec_single()),
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* so save them away before making the call:
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*/
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data_flags = data->flags;
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data->func(data->info);
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/*
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* Unlocked CSDs are valid through generic_exec_single()
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* Unlocked CSDs are valid through generic_exec_single():
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*/
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if (data_flags & CSD_FLAG_LOCK)
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csd_unlock(data);
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@ -276,19 +275,24 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
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.flags = 0,
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};
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unsigned long flags;
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/* prevent preemption and reschedule on another processor,
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as well as CPU removal */
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int me = get_cpu();
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int this_cpu;
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int err = 0;
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/*
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* prevent preemption and reschedule on another processor,
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* as well as CPU removal
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*/
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this_cpu = get_cpu();
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/* Can deadlock when called with interrupts disabled */
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WARN_ON(irqs_disabled());
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if (cpu == me) {
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if (cpu == this_cpu) {
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local_irq_save(flags);
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func(info);
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local_irq_restore(flags);
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} else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
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} else {
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if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
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struct call_single_data *data = &d;
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if (!wait)
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@ -302,8 +306,10 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
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} else {
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err = -ENXIO; /* CPU not online */
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}
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}
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put_cpu();
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return err;
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}
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EXPORT_SYMBOL(smp_call_function_single);
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@ -313,10 +319,9 @@ EXPORT_SYMBOL(smp_call_function_single);
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* @cpu: The CPU to run on.
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* @data: Pre-allocated and setup data structure
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*
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* Like smp_call_function_single(), but allow caller to pass in a pre-allocated
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* data structure. Useful for embedding @data inside other structures, for
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* instance.
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*
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* Like smp_call_function_single(), but allow caller to pass in a
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* pre-allocated data structure. Useful for embedding @data inside
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* other structures, for instance.
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*/
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void __smp_call_function_single(int cpu, struct call_single_data *data,
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int wait)
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@ -329,7 +334,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
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generic_exec_single(cpu, data, wait);
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}
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/* FIXME: Shim for archs using old arch_send_call_function_ipi API. */
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/* Deprecated: shim for archs using old arch_send_call_function_ipi API. */
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#ifndef arch_send_call_function_ipi_mask
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# define arch_send_call_function_ipi_mask(maskp) \
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arch_send_call_function_ipi(*(maskp))
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@ -340,7 +346,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
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* @mask: The set of cpus to run on (only runs on online subset).
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait (atomically) until function has completed on other CPUs.
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* @wait: If true, wait (atomically) until function has completed
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* on other CPUs.
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*
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* If @wait is true, then returns once @func has returned. Note that @wait
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* will be implicitly turned on in case of allocation failures, since
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@ -351,27 +358,27 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
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* must be disabled when calling this function.
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*/
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void smp_call_function_many(const struct cpumask *mask,
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void (*func)(void *), void *info,
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bool wait)
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void (*func)(void *), void *info, bool wait)
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{
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struct call_function_data *data;
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unsigned long flags;
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int cpu, next_cpu, me = smp_processor_id();
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int cpu, next_cpu, this_cpu = smp_processor_id();
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/* Can deadlock when called with interrupts disabled */
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WARN_ON(irqs_disabled());
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/* So, what's a CPU they want? Ignoring this one. */
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cpu = cpumask_first_and(mask, cpu_online_mask);
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if (cpu == me)
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if (cpu == this_cpu)
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cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
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/* No online cpus? We're done. */
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if (cpu >= nr_cpu_ids)
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return;
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/* Do we have another CPU which isn't us? */
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next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
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if (next_cpu == me)
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if (next_cpu == this_cpu)
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next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
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/* Fastpath: do that cpu by itself. */
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@ -387,30 +394,31 @@ void smp_call_function_many(const struct cpumask *mask,
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data->csd.func = func;
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data->csd.info = info;
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cpumask_and(data->cpumask, mask, cpu_online_mask);
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cpumask_clear_cpu(me, data->cpumask);
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cpumask_clear_cpu(this_cpu, data->cpumask);
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data->refs = cpumask_weight(data->cpumask);
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spin_lock(&call_function.lock);
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/*
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* Place entry at the _HEAD_ of the list, so that any cpu still
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* observing the entry in generic_smp_call_function_interrupt() will
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* not miss any other list entries.
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* observing the entry in generic_smp_call_function_interrupt()
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* will not miss any other list entries:
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*/
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list_add_rcu(&data->csd.list, &call_function.queue);
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spin_unlock(&call_function.lock);
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spin_unlock_irqrestore(&data->lock, flags);
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/*
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* Make the list addition visible before sending the ipi.
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* (IPIs must obey or appear to obey normal Linux cache coherency
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* rules -- see comment in generic_exec_single).
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* (IPIs must obey or appear to obey normal Linux cache
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* coherency rules -- see comment in generic_exec_single).
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*/
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smp_mb();
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/* Send a message to all CPUs in the map */
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arch_send_call_function_ipi_mask(data->cpumask);
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/* optionally wait for the CPUs to complete */
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/* Optionally wait for the CPUs to complete */
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if (wait)
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csd_lock_wait(&data->csd);
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}
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@ -420,7 +428,8 @@ EXPORT_SYMBOL(smp_call_function_many);
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* smp_call_function(): Run a function on all other CPUs.
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait (atomically) until function has completed on other CPUs.
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* @wait: If true, wait (atomically) until function has completed
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* on other CPUs.
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*
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* Returns 0.
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*
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@ -436,6 +445,7 @@ int smp_call_function(void (*func)(void *), void *info, int wait)
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preempt_disable();
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smp_call_function_many(cpu_online_mask, func, info, wait);
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preempt_enable();
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return 0;
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}
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EXPORT_SYMBOL(smp_call_function);
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