From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51728269AFB; Fri, 1 Aug 2025 14:12:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754057534; cv=pass; b=tD0XtwrLCnlaaOzwxr2MzVq6TE2bKnt5GrLo+wzSslM8IMU8/15qUFcdFc1eCpZ1tuYY/NZf2okrd6sKFtxTUxiRyyIx7Nc7OJwggEug6TPf9fPSVudeo5clUMiTGUQen6nv+/+Qr1YoZgoneuaae1IZlv7DIXn1o7TLhRwdj8o= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754057534; c=relaxed/simple; bh=mbAvw5BaTOMePlARO4T6j/krBAXicAuUFKo+Q+lSAIA=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=iPpVZEK5XA2XExjI8yA3Soulm/r1OrK2wNgKwREE6+KEe8GngoGKmLMUiE53Xrj7PBxzeskFFrGW7tGfx3y0N94mja1BCgqLSI4aKwV03yataz/NYWOMExcQUoZ5fYB0RXp4ST9ZE4w96RpT0LuxxG6qLwAe5VZ2ypyGJkUkjvw= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=daniel.almeida@collabora.com header.b=OL1Fwqsx; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=daniel.almeida@collabora.com header.b="OL1Fwqsx" ARC-Seal: i=1; a=rsa-sha256; t=1754057521; cv=none; d=zohomail.com; s=zohoarc; b=faQ9HD9f/NwSteKdnDkfiVkVUqMlysNzsQ6hgAb270J4d5UTGvI+SIb6+A40Nlxo6MtLH1wIW1c+G016XAixQQxGMkpnuEZYnGQj84XjveXN2XmVjJP1EokZhAXYLVpc3i//GyVthEDdrle6ZnFoOG9KNF/icru/QhC8iX8sb6c= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1754057521; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=CBT+TzLa9lSSi6LGbYJzkFfqTalTb4QzGiuD/t/Goa0=; b=F3vcNNPQBHTQ9QVbjMKIFQ/bou6jHwzqdQ83xuQ11IiVkBa6QdbYjXL7xbd5xt++FWbB+qY02gzzpFYqTGIccLIrd7ITGmrUUmYaA9Kk4GO83xnHSeHNVE2Y9yXtT7Zuvx3+9zPB4QO0rwQhFhyVd7CnOEo0p34I9rA2+bGL5A8= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=daniel.almeida@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1754057521; s=zohomail; d=collabora.com; i=daniel.almeida@collabora.com; h=Content-Type:Mime-Version:Subject:Subject:From:From:In-Reply-To:Date:Date:Cc:Cc:Content-Transfer-Encoding:Message-Id:Message-Id:References:To:To:Reply-To; bh=CBT+TzLa9lSSi6LGbYJzkFfqTalTb4QzGiuD/t/Goa0=; b=OL1Fwqsxftn5LnMXmKeHDV9L1tkLR22uukju1aF7cVFoPUP7qCFocUnl0mIm6lsp 51cNeq2GOmcaQSBm8pHQdbZWwDH+4xwVfhLw31clTAsyqr8NT0LuZNq7k2qCn9nsTtB hvom8boRkCCQ5hQAd/tK0ecbnjOIWNMWpbHeE9aQ= Received: by mx.zohomail.com with SMTPS id 1754057518977842.1352915038811; Fri, 1 Aug 2025 07:11:58 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3826.600.51.1.1\)) Subject: Re: [RFC PATCH v2 4/4] samples: rust: rust_misc_device: add uring_cmd example From: Daniel Almeida In-Reply-To: <20250727150329.27433-5-sidong.yang@furiosa.ai> Date: Fri, 1 Aug 2025 11:11:44 -0300 Cc: Caleb Sander Mateos , Benno Lossin , Miguel Ojeda , Arnd Bergmann , Jens Axboe , Greg Kroah-Hartman , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20250727150329.27433-1-sidong.yang@furiosa.ai> <20250727150329.27433-5-sidong.yang@furiosa.ai> To: Sidong Yang X-Mailer: Apple Mail (2.3826.600.51.1.1) X-ZohoMailClient: External Hi Sidong, > On 27 Jul 2025, at 12:03, Sidong Yang wrote: >=20 > This patch makes rust_misc_device handle uring_cmd. Command ops are = like > ioctl that set or get values in simple way. >=20 > Signed-off-by: Sidong Yang > --- > samples/rust/rust_misc_device.rs | 34 ++++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) >=20 > diff --git a/samples/rust/rust_misc_device.rs = b/samples/rust/rust_misc_device.rs > index c881fd6dbd08..1044bde86e8d 100644 > --- a/samples/rust/rust_misc_device.rs > +++ b/samples/rust/rust_misc_device.rs > @@ -101,6 +101,7 @@ > c_str, > device::Device, > fs::File, > + io_uring::IoUringCmd, > ioctl::{_IO, _IOC_SIZE, _IOR, _IOW}, > miscdevice::{MiscDevice, MiscDeviceOptions, = MiscDeviceRegistration}, > new_mutex, > @@ -114,6 +115,9 @@ > const RUST_MISC_DEV_GET_VALUE: u32 =3D _IOR::('|' as u32, 0x81); > const RUST_MISC_DEV_SET_VALUE: u32 =3D _IOW::('|' as u32, 0x82); >=20 > +const RUST_MISC_DEV_URING_CMD_SET_VALUE: u32 =3D _IOR::('|' as = u32, 0x83); > +const RUST_MISC_DEV_URING_CMD_GET_VALUE: u32 =3D _IOW::('|' as = u32, 0x84); > + > module! { > type: RustMiscDeviceModule, > name: "rust_misc_device", > @@ -190,6 +194,36 @@ fn ioctl(me: Pin<&RustMiscDevice>, _file: &File, = cmd: u32, arg: usize) -> Result >=20 > Ok(0) > } > + > + fn uring_cmd( > + me: Pin<&RustMiscDevice>, =E2=80=9Cme=E2=80=9D ? > + io_uring_cmd: Pin<&mut IoUringCmd>, > + _issue_flags: u32, > + ) -> Result { > + dev_info!(me.dev, "UringCmd Rust Misc Device Sample\n"); > + > + let cmd =3D io_uring_cmd.cmd_op(); > + let cmd_data =3D io_uring_cmd.sqe().cmd_data().as_ptr() as = *const usize; > + > + // SAFETY: `cmd_data` is guaranteed to be a valid pointer to = the command data > + // within the SQE structure. This is what core::ptr::read_volatile says: Safety Behavior is undefined if any of the following conditions are violated: =E2=80=A2 src must be valid for reads. =E2=80=A2 src must be properly aligned. =E2=80=A2 src must point to a properly initialized value of type T. You must prove that the pre-conditions above are fulfilled here. > + // FIXME: switch to read_once() when it's available. > + let addr =3D unsafe { core::ptr::read_volatile(cmd_data) }; So drivers have to write =E2=80=9Cunsafe=E2=80=9D directly? It isn=E2=80=99= t forbidden, but we should try our best to avoid it. > + > + match cmd { > + RUST_MISC_DEV_URING_CMD_SET_VALUE =3D> { > + me.set_value(UserSlice::new(addr, 8).reader())?; > + } > + RUST_MISC_DEV_URING_CMD_GET_VALUE =3D> { > + me.get_value(UserSlice::new(addr, 8).writer())?; > + } > + _ =3D> { > + dev_err!(me.dev, "-> uring_cmd not recognised: {}\n", = cmd); > + return Err(ENOTTY); > + } > + } > + Ok(0) > + } > } >=20 Who calls this function? > #[pinned_drop] > --=20 > 2.43.0 >=20 >=20 =E2=80=94 Daniel