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io_uring: use private ctx wait queue entries for SQPOLL 

This is in preparation to sharing the poller thread between rings. For
that we need per-ring wait_queue_entry storage, and we can't easily put
that on the stack if one thread is managing multiple rings.

We'll also be sharing the wait_queue_head across rings for the purposes
of wakeups, provide the usual private ring wait_queue_head for now but
make it a pointer so we can easily override it when sharing.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2020-09-02 12:21:41 -06:00
parent ce71bfea20
commit 6a7793828f
1 changed files with 18 additions and 15 deletions
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33
fs/io_uring.c
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@ -287,7 +287,9 @@ struct io_ring_ctx {
/* Only used for accounting purposes */
struct mm_struct *mm_account;
wait_queue_head_t sqo_wait;
struct wait_queue_head *sqo_wait;
struct wait_queue_head __sqo_wait;
struct wait_queue_entry sqo_wait_entry;
/*
* If used, fixed file set. Writers must ensure that ->refs is dead,
@ -1057,7 +1059,8 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
goto err;
ctx->flags = p->flags;
init_waitqueue_head(&ctx->sqo_wait);
init_waitqueue_head(&ctx->__sqo_wait);
ctx->sqo_wait = &ctx->__sqo_wait;
init_waitqueue_head(&ctx->cq_wait);
INIT_LIST_HEAD(&ctx->cq_overflow_list);
init_completion(&ctx->ref_comp);
@ -1340,8 +1343,8 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
{
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
if (waitqueue_active(&ctx->sqo_wait))
wake_up(&ctx->sqo_wait);
if (waitqueue_active(ctx->sqo_wait))
wake_up(ctx->sqo_wait);
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
}
@ -2448,9 +2451,8 @@ static void io_iopoll_req_issued(struct io_kiocb *req)
else
list_add_tail(&req->inflight_entry, &ctx->iopoll_list);
if ((ctx->flags & IORING_SETUP_SQPOLL) &&
wq_has_sleeper(&ctx->sqo_wait))
wake_up(&ctx->sqo_wait);
if ((ctx->flags & IORING_SETUP_SQPOLL) && wq_has_sleeper(ctx->sqo_wait))
wake_up(ctx->sqo_wait);
}
static void __io_state_file_put(struct io_submit_state *state)
@ -6627,10 +6629,11 @@ static int io_sq_thread(void *data)
{
struct io_ring_ctx *ctx = data;
const struct cred *old_cred;
DEFINE_WAIT(wait);
unsigned long timeout;
int ret = 0;
init_wait(&ctx->sqo_wait_entry);
complete(&ctx->sq_thread_comp);
old_cred = override_creds(ctx->creds);
@ -6680,7 +6683,7 @@ static int io_sq_thread(void *data)
continue;
}
prepare_to_wait(&ctx->sqo_wait, &wait,
prepare_to_wait(ctx->sqo_wait, &ctx->sqo_wait_entry,
TASK_INTERRUPTIBLE);
/*
@ -6692,7 +6695,7 @@ static int io_sq_thread(void *data)
*/
if ((ctx->flags & IORING_SETUP_IOPOLL) &&
!list_empty_careful(&ctx->iopoll_list)) {
finish_wait(&ctx->sqo_wait, &wait);
finish_wait(ctx->sqo_wait, &ctx->sqo_wait_entry);
continue;
}
@ -6701,22 +6704,22 @@ static int io_sq_thread(void *data)
to_submit = io_sqring_entries(ctx);
if (!to_submit || ret == -EBUSY) {
if (kthread_should_park()) {
finish_wait(&ctx->sqo_wait, &wait);
finish_wait(ctx->sqo_wait, &ctx->sqo_wait_entry);
break;
}
if (io_run_task_work()) {
finish_wait(&ctx->sqo_wait, &wait);
finish_wait(ctx->sqo_wait, &ctx->sqo_wait_entry);
io_ring_clear_wakeup_flag(ctx);
continue;
}
schedule();
finish_wait(&ctx->sqo_wait, &wait);
finish_wait(ctx->sqo_wait, &ctx->sqo_wait_entry);
io_ring_clear_wakeup_flag(ctx);
ret = 0;
continue;
}
finish_wait(&ctx->sqo_wait, &wait);
finish_wait(ctx->sqo_wait, &ctx->sqo_wait_entry);
io_ring_clear_wakeup_flag(ctx);
}
@ -8659,7 +8662,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
if (!list_empty_careful(&ctx->cq_overflow_list))
io_cqring_overflow_flush(ctx, false, NULL, NULL);
if (flags & IORING_ENTER_SQ_WAKEUP)
wake_up(&ctx->sqo_wait);
wake_up(ctx->sqo_wait);
submitted = to_submit;
} else if (to_submit) {
ret = io_uring_add_task_file(f.file);