Add generic helpers for arch IPI function calls
This adds kernel/smp.c which contains helpers for IPI function calls. In addition to supporting the existing smp_call_function() in a more efficient manner, it also adds a more scalable variant called smp_call_function_single() for calling a given function on a single CPU only. The core of this is based on the x86-64 patch from Nick Piggin, lots of changes since then. "Alan D. Brunelle" <Alan.Brunelle@hp.com> has contributed lots of fixes and suggestions as well. Also thanks to Paul E. McKenney <paulmck@linux.vnet.ibm.com> for reviewing RCU usage and getting rid of the data allocation fallback deadlock. Acked-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe
Родитель
543cf4cb3f
Коммит
3d44223327
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@ -39,3 +39,6 @@ config HAVE_KRETPROBES
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config HAVE_DMA_ATTRS
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def_bool n
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config USE_GENERIC_SMP_HELPERS
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def_bool n
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@ -816,8 +816,9 @@ extern unsigned long xcall_call_function;
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* You must not call this function with disabled interrupts or from a
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* hardware interrupt handler or from a bottom half handler.
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*/
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static int smp_call_function_mask(void (*func)(void *info), void *info,
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int nonatomic, int wait, cpumask_t mask)
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static int sparc64_smp_call_function_mask(void (*func)(void *info), void *info,
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int nonatomic, int wait,
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cpumask_t mask)
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{
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struct call_data_struct data;
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int cpus;
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@ -855,8 +856,8 @@ out_unlock:
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int smp_call_function(void (*func)(void *info), void *info,
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int nonatomic, int wait)
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{
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return smp_call_function_mask(func, info, nonatomic, wait,
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cpu_online_map);
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return sparc64_smp_call_function_mask(func, info, nonatomic, wait,
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cpu_online_map);
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}
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void smp_call_function_client(int irq, struct pt_regs *regs)
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@ -893,7 +894,7 @@ static void tsb_sync(void *info)
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void smp_tsb_sync(struct mm_struct *mm)
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{
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smp_call_function_mask(tsb_sync, mm, 0, 1, mm->cpu_vm_mask);
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sparc64_smp_call_function_mask(tsb_sync, mm, 0, 1, mm->cpu_vm_mask);
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}
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extern unsigned long xcall_flush_tlb_mm;
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@ -7,9 +7,19 @@
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*/
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#include <linux/errno.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/cpumask.h>
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extern void cpu_idle(void);
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struct call_single_data {
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struct list_head list;
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void (*func) (void *info);
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void *info;
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unsigned int flags;
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};
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#ifdef CONFIG_SMP
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#include <linux/preempt.h>
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@ -53,9 +63,28 @@ extern void smp_cpus_done(unsigned int max_cpus);
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* Call a function on all other processors
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*/
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int smp_call_function(void(*func)(void *info), void *info, int retry, int wait);
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int smp_call_function_mask(cpumask_t mask, void(*func)(void *info), void *info,
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int wait);
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int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
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int retry, int wait);
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void __smp_call_function_single(int cpuid, struct call_single_data *data);
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/*
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* Generic and arch helpers
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*/
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#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
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void generic_smp_call_function_single_interrupt(void);
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void generic_smp_call_function_interrupt(void);
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void init_call_single_data(void);
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void ipi_call_lock(void);
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void ipi_call_unlock(void);
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void ipi_call_lock_irq(void);
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void ipi_call_unlock_irq(void);
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#else
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static inline void init_call_single_data(void)
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{
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}
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#endif
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/*
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* Call a function on all processors
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@ -112,7 +141,9 @@ static inline void smp_send_reschedule(int cpu) { }
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})
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#define smp_call_function_mask(mask, func, info, wait) \
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(up_smp_call_function(func, info))
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static inline void init_call_single_data(void)
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{
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}
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#endif /* !SMP */
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/*
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@ -31,6 +31,7 @@
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#include <linux/kernel_stat.h>
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#include <linux/start_kernel.h>
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#include <linux/security.h>
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#include <linux/smp.h>
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#include <linux/workqueue.h>
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#include <linux/profile.h>
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#include <linux/rcupdate.h>
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@ -779,6 +780,7 @@ static void __init do_pre_smp_initcalls(void)
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{
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extern int spawn_ksoftirqd(void);
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init_call_single_data();
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migration_init();
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spawn_ksoftirqd();
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if (!nosoftlockup)
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@ -28,6 +28,7 @@ obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
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obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
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obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
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obj-$(CONFIG_SMP) += cpu.o spinlock.o
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obj-$(CONFIG_USE_GENERIC_SMP_HELPERS) += smp.o
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obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
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obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
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obj-$(CONFIG_UID16) += uid16.o
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@ -0,0 +1,383 @@
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/*
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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/smp.h>
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static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
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static LIST_HEAD(call_function_queue);
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__cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);
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enum {
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CSD_FLAG_WAIT = 0x01,
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CSD_FLAG_ALLOC = 0x02,
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};
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struct call_function_data {
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struct call_single_data csd;
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spinlock_t lock;
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unsigned int refs;
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cpumask_t cpumask;
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struct rcu_head rcu_head;
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};
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struct call_single_queue {
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struct list_head list;
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spinlock_t lock;
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};
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void __cpuinit init_call_single_data(void)
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{
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int i;
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for_each_possible_cpu(i) {
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struct call_single_queue *q = &per_cpu(call_single_queue, i);
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spin_lock_init(&q->lock);
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INIT_LIST_HEAD(&q->list);
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}
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}
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static void csd_flag_wait(struct call_single_data *data)
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{
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/* Wait for response */
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do {
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/*
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* We need to see the flags store in the IPI handler
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*/
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smp_mb();
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if (!(data->flags & CSD_FLAG_WAIT))
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break;
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cpu_relax();
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} while (1);
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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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*/
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static void generic_exec_single(int cpu, struct call_single_data *data)
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{
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struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
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int wait = data->flags & CSD_FLAG_WAIT, ipi;
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unsigned long flags;
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spin_lock_irqsave(&dst->lock, flags);
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ipi = list_empty(&dst->list);
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list_add_tail(&data->list, &dst->list);
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spin_unlock_irqrestore(&dst->lock, flags);
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if (ipi)
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arch_send_call_function_single_ipi(cpu);
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if (wait)
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csd_flag_wait(data);
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}
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static void rcu_free_call_data(struct rcu_head *head)
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{
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struct call_function_data *data;
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data = container_of(head, struct call_function_data, rcu_head);
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kfree(data);
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}
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/*
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* Invoked by arch to handle an IPI for call function. Must be called with
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* interrupts disabled.
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*/
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void generic_smp_call_function_interrupt(void)
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{
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struct call_function_data *data;
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int cpu = get_cpu();
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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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*/
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rcu_read_lock();
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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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if (!cpu_isset(cpu, data->cpumask))
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continue;
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data->csd.func(data->csd.info);
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spin_lock(&data->lock);
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cpu_clear(cpu, data->cpumask);
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WARN_ON(data->refs == 0);
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data->refs--;
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refs = data->refs;
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spin_unlock(&data->lock);
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if (refs)
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continue;
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spin_lock(&call_function_lock);
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list_del_rcu(&data->csd.list);
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spin_unlock(&call_function_lock);
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if (data->csd.flags & CSD_FLAG_WAIT) {
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/*
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* serialize stores to data with the flag clear
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* and wakeup
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*/
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smp_wmb();
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data->csd.flags &= ~CSD_FLAG_WAIT;
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} else
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call_rcu(&data->rcu_head, rcu_free_call_data);
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}
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rcu_read_unlock();
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put_cpu();
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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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*/
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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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/*
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* Need to see other stores to list head for checking whether
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* list is empty without holding q->lock
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*/
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smp_mb();
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while (!list_empty(&q->list)) {
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unsigned int data_flags;
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spin_lock(&q->lock);
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list_replace_init(&q->list, &list);
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spin_unlock(&q->lock);
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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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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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*/
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data_flags = data->flags;
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data->func(data->info);
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if (data_flags & CSD_FLAG_WAIT) {
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smp_wmb();
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data->flags &= ~CSD_FLAG_WAIT;
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} else if (data_flags & CSD_FLAG_ALLOC)
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kfree(data);
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}
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/*
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* See comment on outer loop
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*/
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smp_mb();
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}
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}
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/*
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* smp_call_function_single - Run a function on a specific CPU
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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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* @retry: Unused
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* @wait: If true, wait until function has completed on other CPUs.
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*
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* Returns 0 on success, else a negative status code. Note that @wait
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* will be implicitly turned on in case of allocation failures, since
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* we fall back to on-stack allocation.
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*/
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int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
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int retry, int wait)
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{
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struct call_single_data d;
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unsigned long flags;
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/* prevent preemption and reschedule on another processor */
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int me = 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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local_irq_save(flags);
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func(info);
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local_irq_restore(flags);
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} else {
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struct call_single_data *data = NULL;
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if (!wait) {
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data = kmalloc(sizeof(*data), GFP_ATOMIC);
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if (data)
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data->flags = CSD_FLAG_ALLOC;
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}
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if (!data) {
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data = &d;
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data->flags = CSD_FLAG_WAIT;
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}
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data->func = func;
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data->info = info;
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generic_exec_single(cpu, data);
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}
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put_cpu();
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return 0;
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}
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EXPORT_SYMBOL(smp_call_function_single);
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/**
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* __smp_call_function_single(): Run a function on another CPU
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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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*/
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void __smp_call_function_single(int cpu, struct call_single_data *data)
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{
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/* Can deadlock when called with interrupts disabled */
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WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
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generic_exec_single(cpu, data);
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}
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/**
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* smp_call_function_mask(): Run a function on a set of other CPUs.
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* @mask: The set of cpus to run on.
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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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*
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* Returns 0 on success, else a negative status code.
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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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* we fall back to on-stack allocation.
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*
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* You must not call this function with disabled interrupts or from a
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* hardware interrupt handler or from a bottom half handler. Preemption
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* must be disabled when calling this function.
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*/
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int smp_call_function_mask(cpumask_t mask, void (*func)(void *), void *info,
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int wait)
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{
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struct call_function_data d;
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struct call_function_data *data = NULL;
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cpumask_t allbutself;
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unsigned long flags;
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int cpu, num_cpus;
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/* Can deadlock when called with interrupts disabled */
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WARN_ON(irqs_disabled());
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cpu = smp_processor_id();
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allbutself = cpu_online_map;
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cpu_clear(cpu, allbutself);
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cpus_and(mask, mask, allbutself);
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num_cpus = cpus_weight(mask);
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/*
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* If zero CPUs, return. If just a single CPU, turn this request
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* into a targetted single call instead since it's faster.
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*/
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if (!num_cpus)
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return 0;
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else if (num_cpus == 1) {
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cpu = first_cpu(mask);
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return smp_call_function_single(cpu, func, info, 0, wait);
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}
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if (!wait) {
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data = kmalloc(sizeof(*data), GFP_ATOMIC);
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if (data)
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data->csd.flags = CSD_FLAG_ALLOC;
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}
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if (!data) {
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data = &d;
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data->csd.flags = CSD_FLAG_WAIT;
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}
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spin_lock_init(&data->lock);
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data->csd.func = func;
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data->csd.info = info;
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data->refs = num_cpus;
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data->cpumask = mask;
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spin_lock_irqsave(&call_function_lock, flags);
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list_add_tail_rcu(&data->csd.list, &call_function_queue);
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spin_unlock_irqrestore(&call_function_lock, flags);
|
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/* Send a message to all CPUs in the map */
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arch_send_call_function_ipi(mask);
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/* optionally wait for the CPUs to complete */
|
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if (wait)
|
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csd_flag_wait(&data->csd);
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|
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return 0;
|
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}
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EXPORT_SYMBOL(smp_call_function_mask);
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/**
|
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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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* @natomic: Unused
|
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* @wait: If true, wait (atomically) until function has completed on other CPUs.
|
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*
|
||||
* Returns 0 on success, else a negative status code.
|
||||
*
|
||||
* If @wait is true, then returns once @func has returned; otherwise
|
||||
* it returns just before the target cpu calls @func. In case of allocation
|
||||
* failure, @wait will be implicitly turned on.
|
||||
*
|
||||
* You must not call this function with disabled interrupts or from a
|
||||
* hardware interrupt handler or from a bottom half handler.
|
||||
*/
|
||||
int smp_call_function(void (*func)(void *), void *info, int natomic, int wait)
|
||||
{
|
||||
int ret;
|
||||
|
||||
preempt_disable();
|
||||
ret = smp_call_function_mask(cpu_online_map, func, info, wait);
|
||||
preempt_enable();
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL(smp_call_function);
|
||||
|
||||
void ipi_call_lock(void)
|
||||
{
|
||||
spin_lock(&call_function_lock);
|
||||
}
|
||||
|
||||
void ipi_call_unlock(void)
|
||||
{
|
||||
spin_unlock(&call_function_lock);
|
||||
}
|
||||
|
||||
void ipi_call_lock_irq(void)
|
||||
{
|
||||
spin_lock_irq(&call_function_lock);
|
||||
}
|
||||
|
||||
void ipi_call_unlock_irq(void)
|
||||
{
|
||||
spin_unlock_irq(&call_function_lock);
|
||||
}
|
||||
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