2 * Functions related to softirq rq completions
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/init.h>
8 #include <linux/blkdev.h>
9 #include <linux/interrupt.h>
10 #include <linux/cpu.h>
14 static DEFINE_PER_CPU(struct list_head
, blk_cpu_done
);
17 * Softirq action handler - move entries to local list and loop over them
18 * while passing them to the queue registered handler.
20 static void blk_done_softirq(struct softirq_action
*h
)
22 struct list_head
*cpu_list
, local_list
;
25 cpu_list
= &__get_cpu_var(blk_cpu_done
);
26 list_replace_init(cpu_list
, &local_list
);
29 while (!list_empty(&local_list
)) {
32 rq
= list_entry(local_list
.next
, struct request
, csd
.list
);
33 list_del_init(&rq
->csd
.list
);
34 rq
->q
->softirq_done_fn(rq
);
38 #if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
39 static void trigger_softirq(void *data
)
41 struct request
*rq
= data
;
43 struct list_head
*list
;
45 local_irq_save(flags
);
46 list
= &__get_cpu_var(blk_cpu_done
);
47 list_add_tail(&rq
->csd
.list
, list
);
49 if (list
->next
== &rq
->csd
.list
)
50 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
52 local_irq_restore(flags
);
56 * Setup and invoke a run of 'trigger_softirq' on the given cpu.
58 static int raise_blk_irq(int cpu
, struct request
*rq
)
60 if (cpu_online(cpu
)) {
61 struct call_single_data
*data
= &rq
->csd
;
63 data
->func
= trigger_softirq
;
67 __smp_call_function_single(cpu
, data
, 0);
73 #else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
74 static int raise_blk_irq(int cpu
, struct request
*rq
)
80 static int __cpuinit
blk_cpu_notify(struct notifier_block
*self
,
81 unsigned long action
, void *hcpu
)
84 * If a CPU goes away, splice its entries to the current CPU
85 * and trigger a run of the softirq
87 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
) {
88 int cpu
= (unsigned long) hcpu
;
91 list_splice_init(&per_cpu(blk_cpu_done
, cpu
),
92 &__get_cpu_var(blk_cpu_done
));
93 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
100 static struct notifier_block __cpuinitdata blk_cpu_notifier
= {
101 .notifier_call
= blk_cpu_notify
,
104 void __blk_complete_request(struct request
*req
)
106 int ccpu
, cpu
, group_cpu
= NR_CPUS
;
107 struct request_queue
*q
= req
->q
;
110 BUG_ON(!q
->softirq_done_fn
);
112 local_irq_save(flags
);
113 cpu
= smp_processor_id();
116 * Select completion CPU
118 if (req
->cpu
!= -1) {
120 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &q
->queue_flags
)) {
121 ccpu
= blk_cpu_to_group(ccpu
);
122 group_cpu
= blk_cpu_to_group(cpu
);
128 * If current CPU and requested CPU are in the same group, running
129 * softirq in current CPU. One might concern this is just like
130 * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
131 * running in interrupt handler, and currently I/O controller doesn't
132 * support multiple interrupts, so current CPU is unique actually. This
133 * avoids IPI sending from current CPU to the first CPU of a group.
135 if (ccpu
== cpu
|| ccpu
== group_cpu
) {
136 struct list_head
*list
;
138 list
= &__get_cpu_var(blk_cpu_done
);
139 list_add_tail(&req
->csd
.list
, list
);
142 * if the list only contains our just added request,
143 * signal a raise of the softirq. If there are already
144 * entries there, someone already raised the irq but it
147 if (list
->next
== &req
->csd
.list
)
148 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
149 } else if (raise_blk_irq(ccpu
, req
))
152 local_irq_restore(flags
);
156 * blk_complete_request - end I/O on a request
157 * @req: the request being processed
160 * Ends all I/O on a request. It does not handle partial completions,
161 * unless the driver actually implements this in its completion callback
162 * through requeueing. The actual completion happens out-of-order,
163 * through a softirq handler. The user must have registered a completion
164 * callback through blk_queue_softirq_done().
166 void blk_complete_request(struct request
*req
)
168 if (unlikely(blk_should_fake_timeout(req
->q
)))
170 if (!blk_mark_rq_complete(req
))
171 __blk_complete_request(req
);
173 EXPORT_SYMBOL(blk_complete_request
);
175 static __init
int blk_softirq_init(void)
179 for_each_possible_cpu(i
)
180 INIT_LIST_HEAD(&per_cpu(blk_cpu_done
, i
));
182 open_softirq(BLOCK_SOFTIRQ
, blk_done_softirq
);
183 register_hotcpu_notifier(&blk_cpu_notifier
);
186 subsys_initcall(blk_softirq_init
);