From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-102.mailbox.org (mout-p-102.mailbox.org [80.241.56.152]) (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 AE61326560D; Wed, 21 May 2025 13:03:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.152 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747832603; cv=none; b=RqAw99kDi/FTXHpRU+YBBGt2UxEZfo0h0M8XS6bES9EkQzp27bq5Ulc7Zv2qOwBmo4eQT0hvqvP+goWBT92m6FybcEdLUfUIyiB7O3KZ604LF+3zheWYpQGTxuohGp0AxRVajSi3sZr3SnU2j8Nj9Ew4Rl1ajoD2KZYl2YlcbGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747832603; c=relaxed/simple; bh=dwIYOE3htI9GbHZbf78nxBK6FjqrDFIKmLnz0i4XDIw=; h=Mime-Version:Content-Type:Date:Message-Id:To:Cc:Subject:From: References:In-Reply-To; b=S5DMd8rS6esVeyiIlH9z6aD/7t0ob7bqQ0tvFL8YO7RrGba7VipK3jjsmhJY1NRsSY8dM5ep2e536bjO9F94ONwkEOrBkFNd4KrHYoDumW2+aiK6AsYO5yeMAB2fyhH9yOtcSQqapfKYivd3wTAEANvp/4FGlBkgB+fzd7JC2h8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=buenzli.dev; spf=pass smtp.mailfrom=buenzli.dev; arc=none smtp.client-ip=80.241.56.152 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=buenzli.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=buenzli.dev Received: from smtp102.mailbox.org (smtp102.mailbox.org [IPv6:2001:67c:2050:b231:465::102]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-102.mailbox.org (Postfix) with ESMTPS id 4b2WnD0Hhyz9vJ0; Wed, 21 May 2025 15:03:12 +0200 (CEST) Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 21 May 2025 15:03:07 +0200 Message-Id: To: "Greg Kroah-Hartman" Cc: "Rob Herring" , "Saravana Kannan" , "Miguel Ojeda" , "Alex Gaynor" , "Boqun Feng" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , "Danilo Krummrich" , "Rafael J. Wysocki" , "Dirk Behme" , , , Subject: Re: [PATCH v5 4/9] rust: device: Enable printing fwnode name and path From: "Remo Senekowitsch" References: <20250520200024.268655-1-remo@buenzli.dev> <20250520200024.268655-5-remo@buenzli.dev> <2025052153-steadier-bargraph-e81a@gregkh> In-Reply-To: <2025052153-steadier-bargraph-e81a@gregkh> X-Rspamd-Queue-Id: 4b2WnD0Hhyz9vJ0 On Wed May 21, 2025 at 2:02 PM CEST, Greg Kroah-Hartman wrote: > On Tue, May 20, 2025 at 10:00:19PM +0200, Remo Senekowitsch wrote: >> Add two new public methods `display_name` and `display_path` to >> `FwNode`. They can be used by driver authors for logging purposes. In >> addition, they will be used by core property abstractions for automatic >> logging, for example when a driver attempts to read a required but >> missing property. >>=20 >> Signed-off-by: Remo Senekowitsch >> --- >> rust/kernel/device/property.rs | 72 ++++++++++++++++++++++++++++++++++ >> 1 file changed, 72 insertions(+) >>=20 >> diff --git a/rust/kernel/device/property.rs b/rust/kernel/device/propert= y.rs >> index 70593343bd811..6ccc7947f9c31 100644 >> --- a/rust/kernel/device/property.rs >> +++ b/rust/kernel/device/property.rs >> @@ -32,6 +32,78 @@ pub(crate) fn as_raw(&self) -> *mut bindings::fwnode_= handle { >> self.0.get() >> } >> =20 >> + /// Returns an object that implements [`Display`](core::fmt::Displa= y) for >> + /// printing the name of a node. >> + pub fn display_name(&self) -> impl core::fmt::Display + '_ { >> + struct FwNodeDisplayName<'a>(&'a FwNode); >> + >> + impl core::fmt::Display for FwNodeDisplayName<'_> { >> + fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fm= t::Result { >> + // SAFETY: self is valid by its type invariant >> + let name =3D unsafe { bindings::fwnode_get_name(self.0.= as_raw()) }; >> + if name.is_null() { >> + return Ok(()); > > So if there is no name, you are returning Ok()? Are you sure that's ok > to do? What will the result of the string look like then? In that case we're not writing anything to the formatter, which is equivalent to an empty string. `Ok(())` means that writing succeeded. I assumed that a valid node would always have a name. And we're guaranteed to have a valid node. So I assumed this case would never happen and didn't think too hard about it. But even if a valid node has not name, empty string is probably the correct thing, right?