mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-13 21:56:47 +07:00
c46fff2a3b
The name __smp_call_function_single() doesn't tell much about the properties of this function, especially when compared to smp_call_function_single(). The comments above the implementation are also misleading. The main point of this function is actually not to be able to embed the csd in an object. This is actually a requirement that result from the purpose of this function which is to raise an IPI asynchronously. As such it can be called with interrupts disabled. And this feature comes at the cost of the caller who then needs to serialize the IPIs on this csd. Lets rename the function and enhance the comments so that they reflect these properties. Suggested-by: Christoph Hellwig <hch@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
192 lines
4.6 KiB
C
192 lines
4.6 KiB
C
/*
|
|
* Functions related to softirq rq completions
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/bio.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/cpu.h>
|
|
#include <linux/sched.h>
|
|
|
|
#include "blk.h"
|
|
|
|
static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
|
|
|
|
/*
|
|
* Softirq action handler - move entries to local list and loop over them
|
|
* while passing them to the queue registered handler.
|
|
*/
|
|
static void blk_done_softirq(struct softirq_action *h)
|
|
{
|
|
struct list_head *cpu_list, local_list;
|
|
|
|
local_irq_disable();
|
|
cpu_list = this_cpu_ptr(&blk_cpu_done);
|
|
list_replace_init(cpu_list, &local_list);
|
|
local_irq_enable();
|
|
|
|
while (!list_empty(&local_list)) {
|
|
struct request *rq;
|
|
|
|
rq = list_entry(local_list.next, struct request, queuelist);
|
|
list_del_init(&rq->queuelist);
|
|
rq->q->softirq_done_fn(rq);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static void trigger_softirq(void *data)
|
|
{
|
|
struct request *rq = data;
|
|
unsigned long flags;
|
|
struct list_head *list;
|
|
|
|
local_irq_save(flags);
|
|
list = this_cpu_ptr(&blk_cpu_done);
|
|
/*
|
|
* We reuse queuelist for a list of requests to process. Since the
|
|
* queuelist is used by the block layer only for requests waiting to be
|
|
* submitted to the device it is unused now.
|
|
*/
|
|
list_add_tail(&rq->queuelist, list);
|
|
|
|
if (list->next == &rq->queuelist)
|
|
raise_softirq_irqoff(BLOCK_SOFTIRQ);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/*
|
|
* Setup and invoke a run of 'trigger_softirq' on the given cpu.
|
|
*/
|
|
static int raise_blk_irq(int cpu, struct request *rq)
|
|
{
|
|
if (cpu_online(cpu)) {
|
|
struct call_single_data *data = &rq->csd;
|
|
|
|
data->func = trigger_softirq;
|
|
data->info = rq;
|
|
data->flags = 0;
|
|
|
|
smp_call_function_single_async(cpu, data);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
#else /* CONFIG_SMP */
|
|
static int raise_blk_irq(int cpu, struct request *rq)
|
|
{
|
|
return 1;
|
|
}
|
|
#endif
|
|
|
|
static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
/*
|
|
* If a CPU goes away, splice its entries to the current CPU
|
|
* and trigger a run of the softirq
|
|
*/
|
|
if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
|
|
int cpu = (unsigned long) hcpu;
|
|
|
|
local_irq_disable();
|
|
list_splice_init(&per_cpu(blk_cpu_done, cpu),
|
|
this_cpu_ptr(&blk_cpu_done));
|
|
raise_softirq_irqoff(BLOCK_SOFTIRQ);
|
|
local_irq_enable();
|
|
}
|
|
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block blk_cpu_notifier = {
|
|
.notifier_call = blk_cpu_notify,
|
|
};
|
|
|
|
void __blk_complete_request(struct request *req)
|
|
{
|
|
int ccpu, cpu;
|
|
struct request_queue *q = req->q;
|
|
unsigned long flags;
|
|
bool shared = false;
|
|
|
|
BUG_ON(!q->softirq_done_fn);
|
|
|
|
local_irq_save(flags);
|
|
cpu = smp_processor_id();
|
|
|
|
/*
|
|
* Select completion CPU
|
|
*/
|
|
if (req->cpu != -1) {
|
|
ccpu = req->cpu;
|
|
if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
|
|
shared = cpus_share_cache(cpu, ccpu);
|
|
} else
|
|
ccpu = cpu;
|
|
|
|
/*
|
|
* If current CPU and requested CPU share a cache, run the softirq on
|
|
* the current CPU. One might concern this is just like
|
|
* QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
|
|
* running in interrupt handler, and currently I/O controller doesn't
|
|
* support multiple interrupts, so current CPU is unique actually. This
|
|
* avoids IPI sending from current CPU to the first CPU of a group.
|
|
*/
|
|
if (ccpu == cpu || shared) {
|
|
struct list_head *list;
|
|
do_local:
|
|
list = this_cpu_ptr(&blk_cpu_done);
|
|
list_add_tail(&req->queuelist, list);
|
|
|
|
/*
|
|
* if the list only contains our just added request,
|
|
* signal a raise of the softirq. If there are already
|
|
* entries there, someone already raised the irq but it
|
|
* hasn't run yet.
|
|
*/
|
|
if (list->next == &req->queuelist)
|
|
raise_softirq_irqoff(BLOCK_SOFTIRQ);
|
|
} else if (raise_blk_irq(ccpu, req))
|
|
goto do_local;
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/**
|
|
* blk_complete_request - end I/O on a request
|
|
* @req: the request being processed
|
|
*
|
|
* Description:
|
|
* Ends all I/O on a request. It does not handle partial completions,
|
|
* unless the driver actually implements this in its completion callback
|
|
* through requeueing. The actual completion happens out-of-order,
|
|
* through a softirq handler. The user must have registered a completion
|
|
* callback through blk_queue_softirq_done().
|
|
**/
|
|
void blk_complete_request(struct request *req)
|
|
{
|
|
if (unlikely(blk_should_fake_timeout(req->q)))
|
|
return;
|
|
if (!blk_mark_rq_complete(req))
|
|
__blk_complete_request(req);
|
|
}
|
|
EXPORT_SYMBOL(blk_complete_request);
|
|
|
|
static __init int blk_softirq_init(void)
|
|
{
|
|
int i;
|
|
|
|
for_each_possible_cpu(i)
|
|
INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
|
|
|
|
open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
|
|
register_hotcpu_notifier(&blk_cpu_notifier);
|
|
return 0;
|
|
}
|
|
subsys_initcall(blk_softirq_init);
|