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From: Pavel Begunkov <asml.silence@gmail.com>
To: io-uring@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>, Andres Freund <andres@anarazel.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Darren Hart <dvhart@infradead.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	linux-kernel@vger.kernel.org
Subject: [RFC 4/4] io_uring: implement futex wait
Date: Tue,  1 Jun 2021 15:58:29 +0100	[thread overview]
Message-ID: <e91af9d8f8d6e376635005fd111e9fe7a1c50fea.1622558659.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1622558659.git.asml.silence@gmail.com>

Add futex wait requests, those always go through io-wq for simplicity.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c                 | 38 ++++++++++++++++++++++++++++-------
 include/uapi/linux/io_uring.h |  2 +-
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 99f4f8d9f685..9c3d075a6647 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -670,8 +670,15 @@ struct io_futex {
 	struct file			*file;
 	unsigned int			futex_op;
 
-	unsigned int			nr_wake;
-	unsigned int			wake_op_arg;
+	union {
+		/* wake */
+		struct {
+			unsigned int	nr_wake;
+			unsigned int	wake_op_arg;
+		};
+		/* wait */
+		u32 			val;
+	};
 	unsigned int			flags;
 	void __user			*uaddr;
 };
@@ -5894,10 +5901,23 @@ static int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return -EINVAL;
 
 	v = READ_ONCE(sqe->off);
-	f->nr_wake = (u32)v;
-	f->wake_op_arg = (u32)(v >> 32);
-	f->futex_op = READ_ONCE(sqe->futex_op);
 	f->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	f->futex_op = READ_ONCE(sqe->futex_op);
+
+	switch (f->futex_op) {
+	case IORING_FUTEX_WAKE_OP:
+		f->nr_wake = (u32)v;
+		f->wake_op_arg = (u32)(v >> 32);
+		break;
+	case IORING_FUTEX_WAIT:
+		f->val = (u32)v;
+		if (unlikely(v >> 32))
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -5916,8 +5936,12 @@ static int io_futex(struct io_kiocb *req, unsigned int issue_flags)
 		if (nonblock && ret == -EAGAIN)
 			return -EAGAIN;
 		break;
-	default:
-		ret = -EINVAL;
+	case IORING_FUTEX_WAIT:
+		if (nonblock)
+			return -EAGAIN;
+		ret = futex_wait(f->uaddr, f->flags, f->val, NULL,
+				 FUTEX_BITSET_MATCH_ANY);
+		break;
 	}
 
 	if (ret < 0)
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 6fa5a6e59934..7ab11ee2ce12 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -186,7 +186,7 @@ enum {
 
 enum {
 	IORING_FUTEX_WAKE_OP = 0,
-
+	IORING_FUTEX_WAIT,
 	IORING_FUTEX_LAST,
 };
 
-- 
2.31.1


  parent reply	other threads:[~2021-06-01 14:59 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-01 14:58 [RFC 0/4] futex request support Pavel Begunkov
2021-06-01 14:58 ` [RFC 1/4] futex: add op wake for a single key Pavel Begunkov
2021-06-01 14:58 ` [RFC 2/4] io_uring: frame out futex op Pavel Begunkov
2021-06-01 14:58 ` [RFC 3/4] io_uring: support futex wake requests Pavel Begunkov
2021-06-01 14:58 ` Pavel Begunkov [this message]
2021-06-01 15:45   ` [RFC 4/4] io_uring: implement futex wait Jens Axboe
2021-06-01 15:58     ` Pavel Begunkov
2021-06-01 16:01       ` Jens Axboe
2021-06-01 16:29         ` Pavel Begunkov
2021-06-01 21:53           ` Thomas Gleixner
2021-06-03 10:31             ` Pavel Begunkov
2021-06-04  9:19               ` Thomas Gleixner
2021-06-04 11:58                 ` Pavel Begunkov
2021-06-05  2:09                   ` Thomas Gleixner
2021-06-07 12:14                     ` Pavel Begunkov
2021-06-03 19:03             ` Andres Freund
2021-06-03 21:10               ` Peter Zijlstra
2021-06-03 21:21                 ` Andres Freund
2021-06-05  0:43               ` Thomas Gleixner
2021-06-07 11:31                 ` Pavel Begunkov
2021-06-07 11:48                   ` Peter Zijlstra
2021-06-03 18:59 ` [RFC 0/4] futex request support Andres Freund
2021-06-04 15:26   ` Pavel Begunkov

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