1 // SPDX-License-Identifier: GPL-2.0
3 * Functions related to softirq rq completions
5 #include <linux/kernel.h>
6 #include <linux/module.h>
7 #include <linux/init.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>
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
;
28 cpu_list
= this_cpu_ptr(&blk_cpu_done
);
29 list_replace_init(cpu_list
, &local_list
);
32 while (!list_empty(&local_list
)) {
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
);
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
;
66 smp_call_function_single_async(cpu
, data
);
72 #else /* CONFIG_SMP */
73 static int raise_blk_irq(int cpu
, struct request
*rq
)
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
86 list_splice_init(&per_cpu(blk_cpu_done
, cpu
),
87 this_cpu_ptr(&blk_cpu_done
));
88 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
94 void __blk_complete_request(struct request
*req
)
96 struct request_queue
*q
= req
->q
;
97 int cpu
, ccpu
= req
->mq_ctx
->cpu
;
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
);
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
;
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
135 if (list
->next
== &req
->ipi_list
)
136 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
137 } else if (raise_blk_irq(ccpu
, req
))
140 local_irq_restore(flags
);
143 static __init
int blk_softirq_init(void)
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
);
156 subsys_initcall(blk_softirq_init
);