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![Arnd Bergmann](/assets/img/avatar_default.png)
As of commit966a967116
("smp: Avoid using two cache lines for struct call_single_data"), the smp code prefers 32-byte aligned call_single_data objects for performance reasons, but the block layer includes an instance of this structure in the main 'struct request' that is more senstive to size than to performance here, see4ccafe0320
("block: unalign call_single_data in struct request"). The result is a violation of the calling conventions that clang correctly points out: block/blk-mq.c:630:39: warning: passing 8-byte aligned argument to 32-byte aligned parameter 2 of 'smp_call_function_single_async' may result in an unaligned pointer access [-Walign-mismatch] smp_call_function_single_async(cpu, &rq->csd); It does seem that the usage of the call_single_data without cache line alignment should still be allowed by the smp code, so just change the function prototype so it accepts both, but leave the default alignment unchanged for the other users. This seems better to me than adding a local hack to shut up an otherwise correct warning in the caller. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Jens Axboe <axboe@kernel.dk> Link: https://lkml.kernel.org/r/20210505211300.3174456-1-arnd@kernel.org
1231 lines
33 KiB
C
1231 lines
33 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/irq_work.h>
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#include <linux/rcupdate.h>
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#include <linux/rculist.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/gfp.h>
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#include <linux/smp.h>
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#include <linux/cpu.h>
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#include <linux/sched.h>
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#include <linux/sched/idle.h>
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#include <linux/hypervisor.h>
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#include <linux/sched/clock.h>
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#include <linux/nmi.h>
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#include <linux/sched/debug.h>
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#include <linux/jump_label.h>
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#include "smpboot.h"
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#include "sched/smp.h"
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#define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK)
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#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
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union cfd_seq_cnt {
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u64 val;
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struct {
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u64 src:16;
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u64 dst:16;
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#define CFD_SEQ_NOCPU 0xffff
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u64 type:4;
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#define CFD_SEQ_QUEUE 0
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#define CFD_SEQ_IPI 1
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#define CFD_SEQ_NOIPI 2
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#define CFD_SEQ_PING 3
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#define CFD_SEQ_PINGED 4
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#define CFD_SEQ_HANDLE 5
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#define CFD_SEQ_DEQUEUE 6
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#define CFD_SEQ_IDLE 7
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#define CFD_SEQ_GOTIPI 8
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#define CFD_SEQ_HDLEND 9
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u64 cnt:28;
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} u;
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};
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static char *seq_type[] = {
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[CFD_SEQ_QUEUE] = "queue",
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[CFD_SEQ_IPI] = "ipi",
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[CFD_SEQ_NOIPI] = "noipi",
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[CFD_SEQ_PING] = "ping",
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[CFD_SEQ_PINGED] = "pinged",
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[CFD_SEQ_HANDLE] = "handle",
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[CFD_SEQ_DEQUEUE] = "dequeue (src CPU 0 == empty)",
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[CFD_SEQ_IDLE] = "idle",
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[CFD_SEQ_GOTIPI] = "gotipi",
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[CFD_SEQ_HDLEND] = "hdlend (src CPU 0 == early)",
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};
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struct cfd_seq_local {
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u64 ping;
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u64 pinged;
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u64 handle;
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u64 dequeue;
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u64 idle;
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u64 gotipi;
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u64 hdlend;
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};
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#endif
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struct cfd_percpu {
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call_single_data_t csd;
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#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
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u64 seq_queue;
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u64 seq_ipi;
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u64 seq_noipi;
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#endif
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};
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struct call_function_data {
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struct cfd_percpu __percpu *pcpu;
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cpumask_var_t cpumask;
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cpumask_var_t cpumask_ipi;
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};
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static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
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static void flush_smp_call_function_queue(bool warn_cpu_offline);
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int smpcfd_prepare_cpu(unsigned int cpu)
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{
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struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
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if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
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cpu_to_node(cpu)))
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return -ENOMEM;
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if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
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cpu_to_node(cpu))) {
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free_cpumask_var(cfd->cpumask);
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return -ENOMEM;
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}
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cfd->pcpu = alloc_percpu(struct cfd_percpu);
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if (!cfd->pcpu) {
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free_cpumask_var(cfd->cpumask);
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free_cpumask_var(cfd->cpumask_ipi);
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return -ENOMEM;
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}
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return 0;
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}
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int smpcfd_dead_cpu(unsigned int cpu)
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{
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struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
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free_cpumask_var(cfd->cpumask);
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free_cpumask_var(cfd->cpumask_ipi);
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free_percpu(cfd->pcpu);
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return 0;
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}
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int smpcfd_dying_cpu(unsigned int cpu)
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{
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/*
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* The IPIs for the smp-call-function callbacks queued by other
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* CPUs might arrive late, either due to hardware latencies or
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* because this CPU disabled interrupts (inside stop-machine)
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* before the IPIs were sent. So flush out any pending callbacks
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* explicitly (without waiting for the IPIs to arrive), to
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* ensure that the outgoing CPU doesn't go offline with work
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* still pending.
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*/
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flush_smp_call_function_queue(false);
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irq_work_run();
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return 0;
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}
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void __init call_function_init(void)
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{
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int i;
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for_each_possible_cpu(i)
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init_llist_head(&per_cpu(call_single_queue, i));
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smpcfd_prepare_cpu(smp_processor_id());
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}
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#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
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static DEFINE_STATIC_KEY_FALSE(csdlock_debug_enabled);
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static DEFINE_STATIC_KEY_FALSE(csdlock_debug_extended);
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static int __init csdlock_debug(char *str)
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{
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unsigned int val = 0;
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if (str && !strcmp(str, "ext")) {
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val = 1;
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static_branch_enable(&csdlock_debug_extended);
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} else
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get_option(&str, &val);
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if (val)
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static_branch_enable(&csdlock_debug_enabled);
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return 0;
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}
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early_param("csdlock_debug", csdlock_debug);
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static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
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static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
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static DEFINE_PER_CPU(void *, cur_csd_info);
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static DEFINE_PER_CPU(struct cfd_seq_local, cfd_seq_local);
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#define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC)
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static atomic_t csd_bug_count = ATOMIC_INIT(0);
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static u64 cfd_seq;
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#define CFD_SEQ(s, d, t, c) \
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(union cfd_seq_cnt){ .u.src = s, .u.dst = d, .u.type = t, .u.cnt = c }
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static u64 cfd_seq_inc(unsigned int src, unsigned int dst, unsigned int type)
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{
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union cfd_seq_cnt new, old;
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new = CFD_SEQ(src, dst, type, 0);
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do {
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old.val = READ_ONCE(cfd_seq);
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new.u.cnt = old.u.cnt + 1;
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} while (cmpxchg(&cfd_seq, old.val, new.val) != old.val);
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return old.val;
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}
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#define cfd_seq_store(var, src, dst, type) \
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do { \
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if (static_branch_unlikely(&csdlock_debug_extended)) \
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var = cfd_seq_inc(src, dst, type); \
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} while (0)
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/* Record current CSD work for current CPU, NULL to erase. */
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static void __csd_lock_record(struct __call_single_data *csd)
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{
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if (!csd) {
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smp_mb(); /* NULL cur_csd after unlock. */
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__this_cpu_write(cur_csd, NULL);
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return;
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}
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__this_cpu_write(cur_csd_func, csd->func);
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__this_cpu_write(cur_csd_info, csd->info);
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smp_wmb(); /* func and info before csd. */
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__this_cpu_write(cur_csd, csd);
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smp_mb(); /* Update cur_csd before function call. */
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/* Or before unlock, as the case may be. */
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}
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static __always_inline void csd_lock_record(struct __call_single_data *csd)
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{
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if (static_branch_unlikely(&csdlock_debug_enabled))
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__csd_lock_record(csd);
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}
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static int csd_lock_wait_getcpu(struct __call_single_data *csd)
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{
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unsigned int csd_type;
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csd_type = CSD_TYPE(csd);
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if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC)
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return csd->node.dst; /* Other CSD_TYPE_ values might not have ->dst. */
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return -1;
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}
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static void cfd_seq_data_add(u64 val, unsigned int src, unsigned int dst,
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unsigned int type, union cfd_seq_cnt *data,
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unsigned int *n_data, unsigned int now)
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{
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union cfd_seq_cnt new[2];
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unsigned int i, j, k;
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new[0].val = val;
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new[1] = CFD_SEQ(src, dst, type, new[0].u.cnt + 1);
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for (i = 0; i < 2; i++) {
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if (new[i].u.cnt <= now)
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new[i].u.cnt |= 0x80000000U;
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for (j = 0; j < *n_data; j++) {
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if (new[i].u.cnt == data[j].u.cnt) {
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/* Direct read value trumps generated one. */
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if (i == 0)
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data[j].val = new[i].val;
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break;
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}
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if (new[i].u.cnt < data[j].u.cnt) {
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for (k = *n_data; k > j; k--)
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data[k].val = data[k - 1].val;
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data[j].val = new[i].val;
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(*n_data)++;
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break;
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}
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}
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if (j == *n_data) {
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data[j].val = new[i].val;
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(*n_data)++;
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}
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}
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}
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static const char *csd_lock_get_type(unsigned int type)
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{
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return (type >= ARRAY_SIZE(seq_type)) ? "?" : seq_type[type];
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}
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static void csd_lock_print_extended(struct __call_single_data *csd, int cpu)
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{
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struct cfd_seq_local *seq = &per_cpu(cfd_seq_local, cpu);
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unsigned int srccpu = csd->node.src;
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struct call_function_data *cfd = per_cpu_ptr(&cfd_data, srccpu);
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struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
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unsigned int now;
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union cfd_seq_cnt data[2 * ARRAY_SIZE(seq_type)];
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unsigned int n_data = 0, i;
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data[0].val = READ_ONCE(cfd_seq);
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now = data[0].u.cnt;
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cfd_seq_data_add(pcpu->seq_queue, srccpu, cpu, CFD_SEQ_QUEUE, data, &n_data, now);
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cfd_seq_data_add(pcpu->seq_ipi, srccpu, cpu, CFD_SEQ_IPI, data, &n_data, now);
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cfd_seq_data_add(pcpu->seq_noipi, srccpu, cpu, CFD_SEQ_NOIPI, data, &n_data, now);
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cfd_seq_data_add(per_cpu(cfd_seq_local.ping, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PING, data, &n_data, now);
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cfd_seq_data_add(per_cpu(cfd_seq_local.pinged, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PINGED, data, &n_data, now);
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cfd_seq_data_add(seq->idle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_IDLE, data, &n_data, now);
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cfd_seq_data_add(seq->gotipi, CFD_SEQ_NOCPU, cpu, CFD_SEQ_GOTIPI, data, &n_data, now);
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cfd_seq_data_add(seq->handle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HANDLE, data, &n_data, now);
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cfd_seq_data_add(seq->dequeue, CFD_SEQ_NOCPU, cpu, CFD_SEQ_DEQUEUE, data, &n_data, now);
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cfd_seq_data_add(seq->hdlend, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HDLEND, data, &n_data, now);
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for (i = 0; i < n_data; i++) {
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pr_alert("\tcsd: cnt(%07x): %04x->%04x %s\n",
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data[i].u.cnt & ~0x80000000U, data[i].u.src,
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data[i].u.dst, csd_lock_get_type(data[i].u.type));
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}
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pr_alert("\tcsd: cnt now: %07x\n", now);
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}
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/*
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* Complain if too much time spent waiting. Note that only
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* the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
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* so waiting on other types gets much less information.
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*/
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static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *ts1, int *bug_id)
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{
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int cpu = -1;
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int cpux;
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bool firsttime;
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u64 ts2, ts_delta;
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call_single_data_t *cpu_cur_csd;
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unsigned int flags = READ_ONCE(csd->node.u_flags);
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if (!(flags & CSD_FLAG_LOCK)) {
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if (!unlikely(*bug_id))
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return true;
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cpu = csd_lock_wait_getcpu(csd);
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pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
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*bug_id, raw_smp_processor_id(), cpu);
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return true;
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}
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ts2 = sched_clock();
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ts_delta = ts2 - *ts1;
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if (likely(ts_delta <= CSD_LOCK_TIMEOUT))
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return false;
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firsttime = !*bug_id;
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if (firsttime)
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*bug_id = atomic_inc_return(&csd_bug_count);
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cpu = csd_lock_wait_getcpu(csd);
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if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
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cpux = 0;
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else
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cpux = cpu;
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cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
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pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n",
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firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), ts2 - ts0,
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cpu, csd->func, csd->info);
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if (cpu_cur_csd && csd != cpu_cur_csd) {
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pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
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*bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
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READ_ONCE(per_cpu(cur_csd_info, cpux)));
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} else {
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pr_alert("\tcsd: CSD lock (#%d) %s.\n",
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*bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
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}
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if (cpu >= 0) {
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if (static_branch_unlikely(&csdlock_debug_extended))
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csd_lock_print_extended(csd, cpu);
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if (!trigger_single_cpu_backtrace(cpu))
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dump_cpu_task(cpu);
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if (!cpu_cur_csd) {
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pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
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arch_send_call_function_single_ipi(cpu);
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}
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}
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dump_stack();
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*ts1 = ts2;
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return false;
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}
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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
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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 *csd)
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{
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int bug_id = 0;
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u64 ts0, ts1;
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ts1 = ts0 = sched_clock();
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for (;;) {
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if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id))
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break;
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cpu_relax();
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}
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smp_acquire__after_ctrl_dep();
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}
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static __always_inline void csd_lock_wait(struct __call_single_data *csd)
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{
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if (static_branch_unlikely(&csdlock_debug_enabled)) {
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__csd_lock_wait(csd);
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return;
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}
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smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
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}
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static void __smp_call_single_queue_debug(int cpu, struct llist_node *node)
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{
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unsigned int this_cpu = smp_processor_id();
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struct cfd_seq_local *seq = this_cpu_ptr(&cfd_seq_local);
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struct call_function_data *cfd = this_cpu_ptr(&cfd_data);
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struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
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cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
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if (llist_add(node, &per_cpu(call_single_queue, cpu))) {
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cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
|
|
cfd_seq_store(seq->ping, this_cpu, cpu, CFD_SEQ_PING);
|
|
send_call_function_single_ipi(cpu);
|
|
cfd_seq_store(seq->pinged, this_cpu, cpu, CFD_SEQ_PINGED);
|
|
} else {
|
|
cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
|
|
}
|
|
}
|
|
#else
|
|
#define cfd_seq_store(var, src, dst, type)
|
|
|
|
static void csd_lock_record(struct __call_single_data *csd)
|
|
{
|
|
}
|
|
|
|
static __always_inline void csd_lock_wait(struct __call_single_data *csd)
|
|
{
|
|
smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
|
|
}
|
|
#endif
|
|
|
|
static __always_inline void csd_lock(struct __call_single_data *csd)
|
|
{
|
|
csd_lock_wait(csd);
|
|
csd->node.u_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_t structure:
|
|
*/
|
|
smp_wmb();
|
|
}
|
|
|
|
static __always_inline void csd_unlock(struct __call_single_data *csd)
|
|
{
|
|
WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK));
|
|
|
|
/*
|
|
* ensure we're all done before releasing data:
|
|
*/
|
|
smp_store_release(&csd->node.u_flags, 0);
|
|
}
|
|
|
|
static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
|
|
|
|
void __smp_call_single_queue(int cpu, struct llist_node *node)
|
|
{
|
|
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
|
|
if (static_branch_unlikely(&csdlock_debug_extended)) {
|
|
unsigned int type;
|
|
|
|
type = CSD_TYPE(container_of(node, call_single_data_t,
|
|
node.llist));
|
|
if (type == CSD_TYPE_SYNC || type == CSD_TYPE_ASYNC) {
|
|
__smp_call_single_queue_debug(cpu, node);
|
|
return;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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...
|
|
*/
|
|
if (llist_add(node, &per_cpu(call_single_queue, cpu)))
|
|
send_call_function_single_ipi(cpu);
|
|
}
|
|
|
|
/*
|
|
* Insert a previously allocated call_single_data_t element
|
|
* for execution on the given CPU. data must already have
|
|
* ->func, ->info, and ->flags set.
|
|
*/
|
|
static int generic_exec_single(int cpu, struct __call_single_data *csd)
|
|
{
|
|
if (cpu == smp_processor_id()) {
|
|
smp_call_func_t func = csd->func;
|
|
void *info = csd->info;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* We can unlock early even for the synchronous on-stack case,
|
|
* since we're doing this from the same CPU..
|
|
*/
|
|
csd_lock_record(csd);
|
|
csd_unlock(csd);
|
|
local_irq_save(flags);
|
|
func(info);
|
|
csd_lock_record(NULL);
|
|
local_irq_restore(flags);
|
|
return 0;
|
|
}
|
|
|
|
if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
|
|
csd_unlock(csd);
|
|
return -ENXIO;
|
|
}
|
|
|
|
__smp_call_single_queue(cpu, &csd->node.llist);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
|
|
*
|
|
* Invoked by arch to handle an IPI for call function single.
|
|
* Must be called with interrupts disabled.
|
|
*/
|
|
void generic_smp_call_function_single_interrupt(void)
|
|
{
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->gotipi, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_GOTIPI);
|
|
flush_smp_call_function_queue(true);
|
|
}
|
|
|
|
/**
|
|
* flush_smp_call_function_queue - Flush pending smp-call-function callbacks
|
|
*
|
|
* @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
|
|
* offline CPU. Skip this check if set to 'false'.
|
|
*
|
|
* Flush any pending smp-call-function callbacks queued on this CPU. This is
|
|
* invoked by the generic IPI handler, as well as by a CPU about to go offline,
|
|
* to ensure that all pending IPI callbacks are run before it goes completely
|
|
* offline.
|
|
*
|
|
* Loop through the call_single_queue and run all the queued callbacks.
|
|
* Must be called with interrupts disabled.
|
|
*/
|
|
static void flush_smp_call_function_queue(bool warn_cpu_offline)
|
|
{
|
|
call_single_data_t *csd, *csd_next;
|
|
struct llist_node *entry, *prev;
|
|
struct llist_head *head;
|
|
static bool warned;
|
|
|
|
lockdep_assert_irqs_disabled();
|
|
|
|
head = this_cpu_ptr(&call_single_queue);
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->handle, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_HANDLE);
|
|
entry = llist_del_all(head);
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->dequeue,
|
|
/* Special meaning of source cpu: 0 == queue empty */
|
|
entry ? CFD_SEQ_NOCPU : 0,
|
|
smp_processor_id(), CFD_SEQ_DEQUEUE);
|
|
entry = llist_reverse_order(entry);
|
|
|
|
/* There shouldn't be any pending callbacks on an offline CPU. */
|
|
if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
|
|
!warned && !llist_empty(head))) {
|
|
warned = true;
|
|
WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
|
|
|
|
/*
|
|
* We don't have to use the _safe() variant here
|
|
* because we are not invoking the IPI handlers yet.
|
|
*/
|
|
llist_for_each_entry(csd, entry, node.llist) {
|
|
switch (CSD_TYPE(csd)) {
|
|
case CSD_TYPE_ASYNC:
|
|
case CSD_TYPE_SYNC:
|
|
case CSD_TYPE_IRQ_WORK:
|
|
pr_warn("IPI callback %pS sent to offline CPU\n",
|
|
csd->func);
|
|
break;
|
|
|
|
case CSD_TYPE_TTWU:
|
|
pr_warn("IPI task-wakeup sent to offline CPU\n");
|
|
break;
|
|
|
|
default:
|
|
pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
|
|
CSD_TYPE(csd));
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* First; run all SYNC callbacks, people are waiting for us.
|
|
*/
|
|
prev = NULL;
|
|
llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
|
|
/* Do we wait until *after* callback? */
|
|
if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
|
|
smp_call_func_t func = csd->func;
|
|
void *info = csd->info;
|
|
|
|
if (prev) {
|
|
prev->next = &csd_next->node.llist;
|
|
} else {
|
|
entry = &csd_next->node.llist;
|
|
}
|
|
|
|
csd_lock_record(csd);
|
|
func(info);
|
|
csd_unlock(csd);
|
|
csd_lock_record(NULL);
|
|
} else {
|
|
prev = &csd->node.llist;
|
|
}
|
|
}
|
|
|
|
if (!entry) {
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend,
|
|
0, smp_processor_id(),
|
|
CFD_SEQ_HDLEND);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Second; run all !SYNC callbacks.
|
|
*/
|
|
prev = NULL;
|
|
llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
|
|
int type = CSD_TYPE(csd);
|
|
|
|
if (type != CSD_TYPE_TTWU) {
|
|
if (prev) {
|
|
prev->next = &csd_next->node.llist;
|
|
} else {
|
|
entry = &csd_next->node.llist;
|
|
}
|
|
|
|
if (type == CSD_TYPE_ASYNC) {
|
|
smp_call_func_t func = csd->func;
|
|
void *info = csd->info;
|
|
|
|
csd_lock_record(csd);
|
|
csd_unlock(csd);
|
|
func(info);
|
|
csd_lock_record(NULL);
|
|
} else if (type == CSD_TYPE_IRQ_WORK) {
|
|
irq_work_single(csd);
|
|
}
|
|
|
|
} else {
|
|
prev = &csd->node.llist;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Third; only CSD_TYPE_TTWU is left, issue those.
|
|
*/
|
|
if (entry)
|
|
sched_ttwu_pending(entry);
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_HDLEND);
|
|
}
|
|
|
|
void flush_smp_call_function_from_idle(void)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (llist_empty(this_cpu_ptr(&call_single_queue)))
|
|
return;
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_IDLE);
|
|
local_irq_save(flags);
|
|
flush_smp_call_function_queue(true);
|
|
if (local_softirq_pending())
|
|
do_softirq();
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/*
|
|
* smp_call_function_single - Run a function on a specific CPU
|
|
* @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 until function has completed on other CPUs.
|
|
*
|
|
* Returns 0 on success, else a negative status code.
|
|
*/
|
|
int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
|
|
int wait)
|
|
{
|
|
call_single_data_t *csd;
|
|
call_single_data_t csd_stack = {
|
|
.node = { .u_flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, },
|
|
};
|
|
int this_cpu;
|
|
int err;
|
|
|
|
/*
|
|
* prevent preemption and reschedule on another processor,
|
|
* as well as CPU removal
|
|
*/
|
|
this_cpu = get_cpu();
|
|
|
|
/*
|
|
* Can deadlock when called with interrupts disabled.
|
|
* We allow cpu's that are not yet online though, as no one else can
|
|
* send smp call function interrupt to this cpu and as such deadlocks
|
|
* can't happen.
|
|
*/
|
|
WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
|
&& !oops_in_progress);
|
|
|
|
/*
|
|
* When @wait we can deadlock when we interrupt between llist_add() and
|
|
* arch_send_call_function_ipi*(); when !@wait we can deadlock due to
|
|
* csd_lock() on because the interrupt context uses the same csd
|
|
* storage.
|
|
*/
|
|
WARN_ON_ONCE(!in_task());
|
|
|
|
csd = &csd_stack;
|
|
if (!wait) {
|
|
csd = this_cpu_ptr(&csd_data);
|
|
csd_lock(csd);
|
|
}
|
|
|
|
csd->func = func;
|
|
csd->info = info;
|
|
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
|
|
csd->node.src = smp_processor_id();
|
|
csd->node.dst = cpu;
|
|
#endif
|
|
|
|
err = generic_exec_single(cpu, csd);
|
|
|
|
if (wait)
|
|
csd_lock_wait(csd);
|
|
|
|
put_cpu();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function_single);
|
|
|
|
/**
|
|
* smp_call_function_single_async(): Run an asynchronous function on a
|
|
* specific CPU.
|
|
* @cpu: The CPU to run on.
|
|
* @csd: Pre-allocated and setup data structure
|
|
*
|
|
* Like smp_call_function_single(), but the call is asynchonous and
|
|
* can thus be done from contexts with disabled interrupts.
|
|
*
|
|
* The caller passes his own pre-allocated data structure
|
|
* (ie: embedded in an object) and is responsible for synchronizing it
|
|
* such that the IPIs performed on the @csd are strictly serialized.
|
|
*
|
|
* If the function is called with one csd which has not yet been
|
|
* processed by previous call to smp_call_function_single_async(), the
|
|
* function will return immediately with -EBUSY showing that the csd
|
|
* object is still in progress.
|
|
*
|
|
* NOTE: Be careful, there is unfortunately no current debugging facility to
|
|
* validate the correctness of this serialization.
|
|
*/
|
|
int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
|
|
{
|
|
int err = 0;
|
|
|
|
preempt_disable();
|
|
|
|
if (csd->node.u_flags & CSD_FLAG_LOCK) {
|
|
err = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
csd->node.u_flags = CSD_FLAG_LOCK;
|
|
smp_wmb();
|
|
|
|
err = generic_exec_single(cpu, csd);
|
|
|
|
out:
|
|
preempt_enable();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(smp_call_function_single_async);
|
|
|
|
/*
|
|
* smp_call_function_any - Run a function on any of the given cpus
|
|
* @mask: The mask of cpus it can run on.
|
|
* @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 until function has completed.
|
|
*
|
|
* Returns 0 on success, else a negative status code (if no cpus were online).
|
|
*
|
|
* Selection preference:
|
|
* 1) current cpu if in @mask
|
|
* 2) any cpu of current node if in @mask
|
|
* 3) any other online cpu in @mask
|
|
*/
|
|
int smp_call_function_any(const struct cpumask *mask,
|
|
smp_call_func_t func, void *info, int wait)
|
|
{
|
|
unsigned int cpu;
|
|
const struct cpumask *nodemask;
|
|
int ret;
|
|
|
|
/* Try for same CPU (cheapest) */
|
|
cpu = get_cpu();
|
|
if (cpumask_test_cpu(cpu, mask))
|
|
goto call;
|
|
|
|
/* Try for same node. */
|
|
nodemask = cpumask_of_node(cpu_to_node(cpu));
|
|
for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
|
|
cpu = cpumask_next_and(cpu, nodemask, mask)) {
|
|
if (cpu_online(cpu))
|
|
goto call;
|
|
}
|
|
|
|
/* Any online will do: smp_call_function_single handles nr_cpu_ids. */
|
|
cpu = cpumask_any_and(mask, cpu_online_mask);
|
|
call:
|
|
ret = smp_call_function_single(cpu, func, info, wait);
|
|
put_cpu();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(smp_call_function_any);
|
|
|
|
/*
|
|
* Flags to be used as scf_flags argument of smp_call_function_many_cond().
|
|
*
|
|
* %SCF_WAIT: Wait until function execution is completed
|
|
* %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask
|
|
*/
|
|
#define SCF_WAIT (1U << 0)
|
|
#define SCF_RUN_LOCAL (1U << 1)
|
|
|
|
static void smp_call_function_many_cond(const struct cpumask *mask,
|
|
smp_call_func_t func, void *info,
|
|
unsigned int scf_flags,
|
|
smp_cond_func_t cond_func)
|
|
{
|
|
int cpu, last_cpu, this_cpu = smp_processor_id();
|
|
struct call_function_data *cfd;
|
|
bool wait = scf_flags & SCF_WAIT;
|
|
bool run_remote = false;
|
|
bool run_local = false;
|
|
int nr_cpus = 0;
|
|
|
|
lockdep_assert_preemption_disabled();
|
|
|
|
/*
|
|
* Can deadlock when called with interrupts disabled.
|
|
* We allow cpu's that are not yet online though, as no one else can
|
|
* send smp call function interrupt to this cpu and as such deadlocks
|
|
* can't happen.
|
|
*/
|
|
if (cpu_online(this_cpu) && !oops_in_progress &&
|
|
!early_boot_irqs_disabled)
|
|
lockdep_assert_irqs_enabled();
|
|
|
|
/*
|
|
* When @wait we can deadlock when we interrupt between llist_add() and
|
|
* arch_send_call_function_ipi*(); when !@wait we can deadlock due to
|
|
* csd_lock() on because the interrupt context uses the same csd
|
|
* storage.
|
|
*/
|
|
WARN_ON_ONCE(!in_task());
|
|
|
|
/* Check if we need local execution. */
|
|
if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask))
|
|
run_local = true;
|
|
|
|
/* Check if we need remote execution, i.e., any CPU excluding this one. */
|
|
cpu = cpumask_first_and(mask, cpu_online_mask);
|
|
if (cpu == this_cpu)
|
|
cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
|
if (cpu < nr_cpu_ids)
|
|
run_remote = true;
|
|
|
|
if (run_remote) {
|
|
cfd = this_cpu_ptr(&cfd_data);
|
|
cpumask_and(cfd->cpumask, mask, cpu_online_mask);
|
|
__cpumask_clear_cpu(this_cpu, cfd->cpumask);
|
|
|
|
cpumask_clear(cfd->cpumask_ipi);
|
|
for_each_cpu(cpu, cfd->cpumask) {
|
|
struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
|
|
call_single_data_t *csd = &pcpu->csd;
|
|
|
|
if (cond_func && !cond_func(cpu, info))
|
|
continue;
|
|
|
|
csd_lock(csd);
|
|
if (wait)
|
|
csd->node.u_flags |= CSD_TYPE_SYNC;
|
|
csd->func = func;
|
|
csd->info = info;
|
|
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
|
|
csd->node.src = smp_processor_id();
|
|
csd->node.dst = cpu;
|
|
#endif
|
|
cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
|
|
if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
|
|
__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
|
|
nr_cpus++;
|
|
last_cpu = cpu;
|
|
|
|
cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
|
|
} else {
|
|
cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
|
|
}
|
|
}
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->ping, this_cpu, CFD_SEQ_NOCPU, CFD_SEQ_PING);
|
|
|
|
/*
|
|
* Choose the most efficient way to send an IPI. Note that the
|
|
* number of CPUs might be zero due to concurrent changes to the
|
|
* provided mask.
|
|
*/
|
|
if (nr_cpus == 1)
|
|
send_call_function_single_ipi(last_cpu);
|
|
else if (likely(nr_cpus > 1))
|
|
arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->pinged, this_cpu, CFD_SEQ_NOCPU, CFD_SEQ_PINGED);
|
|
}
|
|
|
|
if (run_local && (!cond_func || cond_func(this_cpu, info))) {
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
func(info);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
if (run_remote && wait) {
|
|
for_each_cpu(cpu, cfd->cpumask) {
|
|
call_single_data_t *csd;
|
|
|
|
csd = &per_cpu_ptr(cfd->pcpu, cpu)->csd;
|
|
csd_lock_wait(csd);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* smp_call_function_many(): Run a function on a set of CPUs.
|
|
* @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.
|
|
* @flags: Bitmask that controls the operation. If %SCF_WAIT is set, wait
|
|
* (atomically) until function has completed on other CPUs. If
|
|
* %SCF_RUN_LOCAL is set, the function will also be run locally
|
|
* if the local CPU is set in the @cpumask.
|
|
*
|
|
* If @wait is true, then returns once @func has returned.
|
|
*
|
|
* You must not call this function with disabled interrupts or from a
|
|
* hardware interrupt handler or from a bottom half handler. Preemption
|
|
* must be disabled when calling this function.
|
|
*/
|
|
void smp_call_function_many(const struct cpumask *mask,
|
|
smp_call_func_t func, void *info, bool wait)
|
|
{
|
|
smp_call_function_many_cond(mask, func, info, wait * SCF_WAIT, NULL);
|
|
}
|
|
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.
|
|
*
|
|
* Returns 0.
|
|
*
|
|
* If @wait is true, then returns once @func has returned; otherwise
|
|
* it returns just before the target cpu calls @func.
|
|
*
|
|
* You must not call this function with disabled interrupts or from a
|
|
* hardware interrupt handler or from a bottom half handler.
|
|
*/
|
|
void smp_call_function(smp_call_func_t func, void *info, int wait)
|
|
{
|
|
preempt_disable();
|
|
smp_call_function_many(cpu_online_mask, func, info, wait);
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function);
|
|
|
|
/* Setup configured maximum number of CPUs to activate */
|
|
unsigned int setup_max_cpus = NR_CPUS;
|
|
EXPORT_SYMBOL(setup_max_cpus);
|
|
|
|
|
|
/*
|
|
* Setup routine for controlling SMP activation
|
|
*
|
|
* Command-line option of "nosmp" or "maxcpus=0" will disable SMP
|
|
* activation entirely (the MPS table probe still happens, though).
|
|
*
|
|
* Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
|
|
* greater than 0, limits the maximum number of CPUs activated in
|
|
* SMP mode to <NUM>.
|
|
*/
|
|
|
|
void __weak arch_disable_smp_support(void) { }
|
|
|
|
static int __init nosmp(char *str)
|
|
{
|
|
setup_max_cpus = 0;
|
|
arch_disable_smp_support();
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("nosmp", nosmp);
|
|
|
|
/* this is hard limit */
|
|
static int __init nrcpus(char *str)
|
|
{
|
|
int nr_cpus;
|
|
|
|
if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
|
|
nr_cpu_ids = nr_cpus;
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("nr_cpus", nrcpus);
|
|
|
|
static int __init maxcpus(char *str)
|
|
{
|
|
get_option(&str, &setup_max_cpus);
|
|
if (setup_max_cpus == 0)
|
|
arch_disable_smp_support();
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("maxcpus", maxcpus);
|
|
|
|
/* Setup number of possible processor ids */
|
|
unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
|
|
EXPORT_SYMBOL(nr_cpu_ids);
|
|
|
|
/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
|
|
void __init setup_nr_cpu_ids(void)
|
|
{
|
|
nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
|
|
}
|
|
|
|
/* Called by boot processor to activate the rest. */
|
|
void __init smp_init(void)
|
|
{
|
|
int num_nodes, num_cpus;
|
|
|
|
idle_threads_init();
|
|
cpuhp_threads_init();
|
|
|
|
pr_info("Bringing up secondary CPUs ...\n");
|
|
|
|
bringup_nonboot_cpus(setup_max_cpus);
|
|
|
|
num_nodes = num_online_nodes();
|
|
num_cpus = num_online_cpus();
|
|
pr_info("Brought up %d node%s, %d CPU%s\n",
|
|
num_nodes, (num_nodes > 1 ? "s" : ""),
|
|
num_cpus, (num_cpus > 1 ? "s" : ""));
|
|
|
|
/* Any cleanup work */
|
|
smp_cpus_done(setup_max_cpus);
|
|
}
|
|
|
|
/*
|
|
* on_each_cpu_cond(): Call a function on each processor for which
|
|
* the supplied function cond_func returns true, optionally waiting
|
|
* for all the required CPUs to finish. This may include the local
|
|
* processor.
|
|
* @cond_func: A callback function that is passed a cpu id and
|
|
* the info parameter. The function is called
|
|
* with preemption disabled. The function should
|
|
* return a blooean value indicating whether to IPI
|
|
* the specified CPU.
|
|
* @func: The function to run on all applicable CPUs.
|
|
* This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to both functions.
|
|
* @wait: If true, wait (atomically) until function has
|
|
* completed on other CPUs.
|
|
*
|
|
* Preemption is disabled to protect against CPUs going offline but not online.
|
|
* CPUs going online during the call will not be seen or sent an IPI.
|
|
*
|
|
* You must not call this function with disabled interrupts or
|
|
* from a hardware interrupt handler or from a bottom half handler.
|
|
*/
|
|
void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
|
|
void *info, bool wait, const struct cpumask *mask)
|
|
{
|
|
unsigned int scf_flags = SCF_RUN_LOCAL;
|
|
|
|
if (wait)
|
|
scf_flags |= SCF_WAIT;
|
|
|
|
preempt_disable();
|
|
smp_call_function_many_cond(mask, func, info, scf_flags, cond_func);
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(on_each_cpu_cond_mask);
|
|
|
|
static void do_nothing(void *unused)
|
|
{
|
|
}
|
|
|
|
/**
|
|
* kick_all_cpus_sync - Force all cpus out of idle
|
|
*
|
|
* Used to synchronize the update of pm_idle function pointer. It's
|
|
* called after the pointer is updated and returns after the dummy
|
|
* callback function has been executed on all cpus. The execution of
|
|
* the function can only happen on the remote cpus after they have
|
|
* left the idle function which had been called via pm_idle function
|
|
* pointer. So it's guaranteed that nothing uses the previous pointer
|
|
* anymore.
|
|
*/
|
|
void kick_all_cpus_sync(void)
|
|
{
|
|
/* Make sure the change is visible before we kick the cpus */
|
|
smp_mb();
|
|
smp_call_function(do_nothing, NULL, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
|
|
|
|
/**
|
|
* wake_up_all_idle_cpus - break all cpus out of idle
|
|
* wake_up_all_idle_cpus try to break all cpus which is in idle state even
|
|
* including idle polling cpus, for non-idle cpus, we will do nothing
|
|
* for them.
|
|
*/
|
|
void wake_up_all_idle_cpus(void)
|
|
{
|
|
int cpu;
|
|
|
|
preempt_disable();
|
|
for_each_online_cpu(cpu) {
|
|
if (cpu == smp_processor_id())
|
|
continue;
|
|
|
|
wake_up_if_idle(cpu);
|
|
}
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
|
|
|
|
/**
|
|
* smp_call_on_cpu - Call a function on a specific cpu
|
|
*
|
|
* Used to call a function on a specific cpu and wait for it to return.
|
|
* Optionally make sure the call is done on a specified physical cpu via vcpu
|
|
* pinning in order to support virtualized environments.
|
|
*/
|
|
struct smp_call_on_cpu_struct {
|
|
struct work_struct work;
|
|
struct completion done;
|
|
int (*func)(void *);
|
|
void *data;
|
|
int ret;
|
|
int cpu;
|
|
};
|
|
|
|
static void smp_call_on_cpu_callback(struct work_struct *work)
|
|
{
|
|
struct smp_call_on_cpu_struct *sscs;
|
|
|
|
sscs = container_of(work, struct smp_call_on_cpu_struct, work);
|
|
if (sscs->cpu >= 0)
|
|
hypervisor_pin_vcpu(sscs->cpu);
|
|
sscs->ret = sscs->func(sscs->data);
|
|
if (sscs->cpu >= 0)
|
|
hypervisor_pin_vcpu(-1);
|
|
|
|
complete(&sscs->done);
|
|
}
|
|
|
|
int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
|
|
{
|
|
struct smp_call_on_cpu_struct sscs = {
|
|
.done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
|
|
.func = func,
|
|
.data = par,
|
|
.cpu = phys ? cpu : -1,
|
|
};
|
|
|
|
INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
|
|
|
|
if (cpu >= nr_cpu_ids || !cpu_online(cpu))
|
|
return -ENXIO;
|
|
|
|
queue_work_on(cpu, system_wq, &sscs.work);
|
|
wait_for_completion(&sscs.done);
|
|
|
|
return sscs.ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(smp_call_on_cpu);
|