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charset=UTF-8 Date: Sat, 25 Apr 2026 12:04:31 +0900 Message-Id: From: "Alexandre Courbot" To: "Gary Guo" Cc: "Danilo Krummrich" , "Alice Ryhl" , "David Airlie" , "Simona Vetter" , "Bjorn Helgaas" , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , "Miguel Ojeda" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Trevor Gross" , "Boqun Feng" , "John Hubbard" , "Alistair Popple" , "Joel Fernandes" , "Timur Tabi" , "Eliot Courtney" , , , , , Subject: Re: [PATCH v2 1/5] rust: add warn_on_err macro References: <20260421-nova-unload-v2-0-2fe54963af8b@nvidia.com> <20260421-nova-unload-v2-1-2fe54963af8b@nvidia.com> In-Reply-To: X-ClientProxiedBy: TYCP286CA0128.JPNP286.PROD.OUTLOOK.COM (2603:1096:400:2b6::18) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PR12MB3990:EE_|MW6PR12MB8868:EE_ X-MS-Office365-Filtering-Correlation-Id: a00be8eb-c911-433a-c424-08dea277611c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|10070799003|7416014|376014|1800799024|56012099003|22082099003|18002099003; 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Add a helper macro th= at >>>> allows this. >>>> >>>> Signed-off-by: Alexandre Courbot >>>> --- >>>> rust/kernel/bug.rs | 10 ++++++++++ >>>> 1 file changed, 10 insertions(+) >>>> >>>> diff --git a/rust/kernel/bug.rs b/rust/kernel/bug.rs >>>> index ed943960f851..2fefc0aeef81 100644 >>>> --- a/rust/kernel/bug.rs >>>> +++ b/rust/kernel/bug.rs >>>> @@ -130,3 +130,13 @@ macro_rules! warn_on { >>>> cond >>>> }}; >>>> } >>>> + >>>> +/// Report a warning if `res` is an error and return it unmodified. >>>> +#[macro_export] >>>> +macro_rules! warn_on_err { >>>> + ($res:expr) =3D> {{ >>>> + let res =3D $res; >>>> + let _ =3D $crate::warn_on!(res.is_err()); >>>> + res >>>> + }}; >>>> +} >>> >>> >>> I think `warn_on_err` could just be expressed as >>> >>> res.inspect_err(|_| warn_on!(true)) >> >> This would turn the verbose error message into something like >> >> [true] module.rs >> >> I.e. the expression passed as argument won't be printed. >> >> That being said, my version has the exact same problem and I don't see >> how we can fix this without splitting `warn_on` and making it more >> complex. >> >> Since this was done as a small convenience, I think I will just remove >> this from this patchset and revisit later as a separate series. > > Something like this? > > #[macro_export] > macro_rules! warn { > () =3D> {{ > const WARN_ON_FLAGS: u32 =3D $crate::bug::bugflag_taint($crate::b= indings::TAINT_WARN); > > $crate::warn_flags!(file!(), WARN_ON_FLAGS); > }} > ($msg:expr) =3D> {{ > #[cfg(CONFIG_DEBUG_BUGVERBOSE_DETAILED)] > const _COND_STR: &str =3D concat!("[", $msg, "] ", file!()); > #[cfg(not(CONFIG_DEBUG_BUGVERBOSE_DETAILED))] > const _COND_STR: &str =3D file!(); > > const WARN_ON_FLAGS: u32 =3D $crate::bug::bugflag_taint($crate::b= indings::TAINT_WARN); > > $crate::warn_flags!(_COND_STR, WARN_ON_FLAGS); > }}; > } > > #[macro_export] > macro_rules! warn_on { > ($cond:expr) =3D> {{ > let cond =3D $cond; > if cond { > warn!(stringify!($cond)); > } > cond > }}; > } > > Then you can just use a `warn!()` with custom message. Exactly. But this is getting more involved than I initially thought and will likely require more review, for a marginal improvement on the Nova unload code - so let's do that as a separate series (that will also allow us to merge it through the Rust tree).