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From: Jens Axboe <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>
Subject: [PATCH 4/6] io_uring: set task_work notify method at init time
Date: Mon, 25 Apr 2022 08:21:16 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

While doing so, switch SQPOLL to TWA_SIGNAL_NO_IPI as well, as that
just does a task wakeup and then we can remove the special wakeup we
have in task_work_add.

Signed-off-by: Jens Axboe <[email protected]>
---
 fs/io_uring.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 511b52e4b9fd..7e9ac5fd3a8c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -367,6 +367,7 @@ struct io_ring_ctx {
 
 		struct io_rings		*rings;
 		unsigned int		flags;
+		enum task_work_notify_mode	notify_method;
 		unsigned int		compat: 1;
 		unsigned int		drain_next: 1;
 		unsigned int		restricted: 1;
@@ -2651,8 +2652,8 @@ static void tctx_task_work(struct callback_head *cb)
 static void io_req_task_work_add(struct io_kiocb *req, bool priority)
 {
 	struct task_struct *tsk = req->task;
+	struct io_ring_ctx *ctx = req->ctx;
 	struct io_uring_task *tctx = tsk->io_uring;
-	enum task_work_notify_mode notify;
 	struct io_wq_work_node *node;
 	unsigned long flags;
 	bool running;
@@ -2675,18 +2676,8 @@ static void io_req_task_work_add(struct io_kiocb *req, bool priority)
 	if (running)
 		return;
 
-	/*
-	 * SQPOLL kernel thread doesn't need notification, just a wakeup. For
-	 * all other cases, use TWA_SIGNAL unconditionally to ensure we're
-	 * processing task_work. There's no reliable way to tell if TWA_RESUME
-	 * will do the job.
-	 */
-	notify = (req->ctx->flags & IORING_SETUP_SQPOLL) ? TWA_NONE : TWA_SIGNAL;
-	if (likely(!task_work_add(tsk, &tctx->task_work, notify))) {
-		if (notify == TWA_NONE)
-			wake_up_process(tsk);
+	if (likely(!task_work_add(tsk, &tctx->task_work, ctx->notify_method)))
 		return;
-	}
 
 	spin_lock_irqsave(&tctx->task_lock, flags);
 	tctx->task_running = false;
@@ -11704,6 +11695,14 @@ static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
 	if (!capable(CAP_IPC_LOCK))
 		ctx->user = get_uid(current_user());
 
+	/*
+	 * For SQPOLL, we just need a wakeup, always.
+	 */
+	if (ctx->flags & IORING_SETUP_SQPOLL)
+		ctx->notify_method = TWA_SIGNAL_NO_IPI;
+	else
+		ctx->notify_method = TWA_SIGNAL;
+
 	/*
 	 * This is just grabbed for accounting purposes. When a process exits,
 	 * the mm is exited and dropped before the files, hence we need to hang
-- 
2.35.1


  parent reply	other threads:[~2022-04-25 14:21 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-25 14:21 [PATCHSET v3 next 0/5] Add support for non-IPI task_work Jens Axboe
2022-04-25 14:21 ` [PATCH 1/6] task_work: allow TWA_SIGNAL without a rescheduling IPI Jens Axboe
2022-04-25 14:21 ` [PATCH 2/6] io_uring: serialize ctx->rings->sq_flags with atomic_or/and Jens Axboe
2022-04-25 14:21 ` [PATCH 3/6] io-wq: use __set_notify_signal() to wake workers Jens Axboe
2022-04-25 14:21 ` Jens Axboe [this message]
2022-04-25 14:21 ` [PATCH 5/6] io_uring: use TWA_SIGNAL_NO_IPI if IORING_SETUP_COOP_TASKRUN is used Jens Axboe
2022-04-25 14:21 ` [PATCH 6/6] io_uring: add IORING_SETUP_TASKRUN_FLAG Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2022-04-26  1:48 [PATCHSET v4 next 0/5] Add support for non-IPI task_work Jens Axboe
2022-04-26  1:49 ` [PATCH 4/6] io_uring: set task_work notify method at init time Jens Axboe

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