blk-mq: optimise rq sort function
[linux/fpc-iii.git] / block / blk-softirq.c
blob6e7ec87d49faa11eabdded4b01adf33ceaae9037
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Functions related to softirq rq completions
4 */
5 #include <linux/kernel.h>
6 #include <linux/module.h>
7 #include <linux/init.h>
8 #include <linux/bio.h>
9 #include <linux/blkdev.h>
10 #include <linux/interrupt.h>
11 #include <linux/cpu.h>
12 #include <linux/sched.h>
13 #include <linux/sched/topology.h>
15 #include "blk.h"
17 static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
20 * Softirq action handler - move entries to local list and loop over them
21 * while passing them to the queue registered handler.
23 static __latent_entropy void blk_done_softirq(struct softirq_action *h)
25 struct list_head *cpu_list, local_list;
27 local_irq_disable();
28 cpu_list = this_cpu_ptr(&blk_cpu_done);
29 list_replace_init(cpu_list, &local_list);
30 local_irq_enable();
32 while (!list_empty(&local_list)) {
33 struct request *rq;
35 rq = list_entry(local_list.next, struct request, ipi_list);
36 list_del_init(&rq->ipi_list);
37 rq->q->mq_ops->complete(rq);
41 #ifdef CONFIG_SMP
42 static void trigger_softirq(void *data)
44 struct request *rq = data;
45 struct list_head *list;
47 list = this_cpu_ptr(&blk_cpu_done);
48 list_add_tail(&rq->ipi_list, list);
50 if (list->next == &rq->ipi_list)
51 raise_softirq_irqoff(BLOCK_SOFTIRQ);
55 * Setup and invoke a run of 'trigger_softirq' on the given cpu.
57 static int raise_blk_irq(int cpu, struct request *rq)
59 if (cpu_online(cpu)) {
60 call_single_data_t *data = &rq->csd;
62 data->func = trigger_softirq;
63 data->info = rq;
64 data->flags = 0;
66 smp_call_function_single_async(cpu, data);
67 return 0;
70 return 1;
72 #else /* CONFIG_SMP */
73 static int raise_blk_irq(int cpu, struct request *rq)
75 return 1;
77 #endif
79 static int blk_softirq_cpu_dead(unsigned int cpu)
82 * If a CPU goes away, splice its entries to the current CPU
83 * and trigger a run of the softirq
85 local_irq_disable();
86 list_splice_init(&per_cpu(blk_cpu_done, cpu),
87 this_cpu_ptr(&blk_cpu_done));
88 raise_softirq_irqoff(BLOCK_SOFTIRQ);
89 local_irq_enable();
91 return 0;
94 void __blk_complete_request(struct request *req)
96 struct request_queue *q = req->q;
97 int cpu, ccpu = req->mq_ctx->cpu;
98 unsigned long flags;
99 bool shared = false;
101 BUG_ON(!q->mq_ops->complete);
103 local_irq_save(flags);
104 cpu = smp_processor_id();
107 * Select completion CPU
109 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && ccpu != -1) {
110 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
111 shared = cpus_share_cache(cpu, ccpu);
112 } else
113 ccpu = cpu;
116 * If current CPU and requested CPU share a cache, run the softirq on
117 * the current CPU. One might concern this is just like
118 * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
119 * running in interrupt handler, and currently I/O controller doesn't
120 * support multiple interrupts, so current CPU is unique actually. This
121 * avoids IPI sending from current CPU to the first CPU of a group.
123 if (ccpu == cpu || shared) {
124 struct list_head *list;
125 do_local:
126 list = this_cpu_ptr(&blk_cpu_done);
127 list_add_tail(&req->ipi_list, list);
130 * if the list only contains our just added request,
131 * signal a raise of the softirq. If there are already
132 * entries there, someone already raised the irq but it
133 * hasn't run yet.
135 if (list->next == &req->ipi_list)
136 raise_softirq_irqoff(BLOCK_SOFTIRQ);
137 } else if (raise_blk_irq(ccpu, req))
138 goto do_local;
140 local_irq_restore(flags);
143 static __init int blk_softirq_init(void)
145 int i;
147 for_each_possible_cpu(i)
148 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
150 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
151 cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
152 "block/softirq:dead", NULL,
153 blk_softirq_cpu_dead);
154 return 0;
156 subsys_initcall(blk_softirq_init);