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io_uring: complete notifiers in tw

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We need a task context to post CQEs but using wq is too expensive.
Try to complete notifiers using task_work and fall back to wq if fails.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/089799ab665b10b78fdc614ae6d59fa7ef0d5f91.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2022-07-12 21:52:40 +01:00 committed by Jens Axboe
parent eb4a299b2f
commit e58d498e81
2 changed files with 22 additions and 3 deletions
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22
io_uring/notif.c
View file

@ -13,6 +13,11 @@ static void __io_notif_complete_tw(struct callback_head *cb)
struct io_notif *notif = container_of(cb, struct io_notif, task_work);
struct io_ring_ctx *ctx = notif->ctx;
if (likely(notif->task)) {
io_put_task(notif->task, 1);
notif->task = NULL;
}
io_cq_lock(ctx);
io_fill_cqe_aux(ctx, notif->tag, 0, notif->seq, true);
@ -43,6 +48,14 @@ static void io_uring_tx_zerocopy_callback(struct sk_buff *skb,
if (!refcount_dec_and_test(&uarg->refcnt))
return;
if (likely(notif->task)) {
init_task_work(&notif->task_work, __io_notif_complete_tw);
if (likely(!task_work_add(notif->task, &notif->task_work,
TWA_SIGNAL)))
return;
}
INIT_WORK(&notif->commit_work, io_notif_complete_wq);
queue_work(system_unbound_wq, &notif->commit_work);
}
@ -134,12 +147,15 @@ __cold int io_notif_unregister(struct io_ring_ctx *ctx)
for (i = 0; i < ctx->nr_notif_slots; i++) {
struct io_notif_slot *slot = &ctx->notif_slots[i];
if (slot->notif)
io_notif_slot_flush(slot);
if (!slot->notif)
continue;
if (WARN_ON_ONCE(slot->notif->task))
slot->notif->task = NULL;
io_notif_slot_flush(slot);
}
kvfree(ctx->notif_slots);
ctx->notif_slots = NULL;
ctx->nr_notif_slots = 0;
return 0;
}
}

3
io_uring/notif.h
View file

@ -11,6 +11,9 @@ struct io_notif {
struct ubuf_info uarg;
struct io_ring_ctx *ctx;
/* complete via tw if ->task is non-NULL, fallback to wq otherwise */
struct task_struct *task;
/* cqe->user_data, io_notif_slot::tag if not overridden */
u64 tag;
/* see struct io_notif_slot::seq */