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![Paul Gortmaker](/assets/img/avatar_default.png)
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0
("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
This removes all the drivers/block uses of the __cpuinit macros
from all C files.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
186 lines
4.5 KiB
C
186 lines
4.5 KiB
C
/*
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* Functions related to softirq rq completions
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/interrupt.h>
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#include <linux/cpu.h>
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#include <linux/sched.h>
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#include "blk.h"
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static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
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/*
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* Softirq action handler - move entries to local list and loop over them
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* while passing them to the queue registered handler.
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*/
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static void blk_done_softirq(struct softirq_action *h)
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{
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struct list_head *cpu_list, local_list;
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local_irq_disable();
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cpu_list = &__get_cpu_var(blk_cpu_done);
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list_replace_init(cpu_list, &local_list);
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local_irq_enable();
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while (!list_empty(&local_list)) {
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struct request *rq;
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rq = list_entry(local_list.next, struct request, csd.list);
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list_del_init(&rq->csd.list);
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rq->q->softirq_done_fn(rq);
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}
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}
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#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
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static void trigger_softirq(void *data)
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{
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struct request *rq = data;
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unsigned long flags;
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struct list_head *list;
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local_irq_save(flags);
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list = &__get_cpu_var(blk_cpu_done);
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list_add_tail(&rq->csd.list, list);
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if (list->next == &rq->csd.list)
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raise_softirq_irqoff(BLOCK_SOFTIRQ);
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local_irq_restore(flags);
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}
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/*
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* Setup and invoke a run of 'trigger_softirq' on the given cpu.
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*/
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static int raise_blk_irq(int cpu, struct request *rq)
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{
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if (cpu_online(cpu)) {
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struct call_single_data *data = &rq->csd;
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data->func = trigger_softirq;
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data->info = rq;
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data->flags = 0;
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__smp_call_function_single(cpu, data, 0);
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return 0;
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}
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return 1;
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}
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#else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
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static int raise_blk_irq(int cpu, struct request *rq)
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{
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return 1;
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}
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#endif
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static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
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void *hcpu)
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{
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/*
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* If a CPU goes away, splice its entries to the current CPU
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* and trigger a run of the softirq
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*/
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if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
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int cpu = (unsigned long) hcpu;
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local_irq_disable();
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list_splice_init(&per_cpu(blk_cpu_done, cpu),
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&__get_cpu_var(blk_cpu_done));
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raise_softirq_irqoff(BLOCK_SOFTIRQ);
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local_irq_enable();
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}
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return NOTIFY_OK;
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}
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static struct notifier_block blk_cpu_notifier = {
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.notifier_call = blk_cpu_notify,
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};
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void __blk_complete_request(struct request *req)
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{
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int ccpu, cpu;
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struct request_queue *q = req->q;
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unsigned long flags;
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bool shared = false;
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BUG_ON(!q->softirq_done_fn);
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local_irq_save(flags);
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cpu = smp_processor_id();
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/*
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* Select completion CPU
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*/
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if (req->cpu != -1) {
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ccpu = req->cpu;
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if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
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shared = cpus_share_cache(cpu, ccpu);
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} else
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ccpu = cpu;
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/*
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* If current CPU and requested CPU share a cache, run the softirq on
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* the current CPU. One might concern this is just like
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* QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
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* running in interrupt handler, and currently I/O controller doesn't
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* support multiple interrupts, so current CPU is unique actually. This
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* avoids IPI sending from current CPU to the first CPU of a group.
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*/
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if (ccpu == cpu || shared) {
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struct list_head *list;
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do_local:
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list = &__get_cpu_var(blk_cpu_done);
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list_add_tail(&req->csd.list, list);
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/*
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* if the list only contains our just added request,
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* signal a raise of the softirq. If there are already
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* entries there, someone already raised the irq but it
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* hasn't run yet.
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*/
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if (list->next == &req->csd.list)
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raise_softirq_irqoff(BLOCK_SOFTIRQ);
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} else if (raise_blk_irq(ccpu, req))
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goto do_local;
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local_irq_restore(flags);
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}
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/**
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* blk_complete_request - end I/O on a request
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* @req: the request being processed
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*
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* Description:
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* Ends all I/O on a request. It does not handle partial completions,
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* unless the driver actually implements this in its completion callback
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* through requeueing. The actual completion happens out-of-order,
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* through a softirq handler. The user must have registered a completion
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* callback through blk_queue_softirq_done().
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**/
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void blk_complete_request(struct request *req)
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{
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if (unlikely(blk_should_fake_timeout(req->q)))
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return;
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if (!blk_mark_rq_complete(req))
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__blk_complete_request(req);
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}
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EXPORT_SYMBOL(blk_complete_request);
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static __init int blk_softirq_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_LIST_HEAD(&per_cpu(blk_cpu_done, i));
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open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
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register_hotcpu_notifier(&blk_cpu_notifier);
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return 0;
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}
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subsys_initcall(blk_softirq_init);
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