From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 926F04A5EAA for ; Thu, 3 Sep 2026 12:43:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788439435; cv=none; b=BX5kOzUuNbQAufH85YcLw/B3N95N0kPqFIsF36cvcK4wo9VUpIAS4AaPJkf104ry2qpFiv/ThDsCFdQiRAs0AVFfVRdU5xt8KpU3Bp9uraHCTOi2yVZ9w3BjGFGId25HBidIpZ9fINlksCa0/dUllbbqaRji/RfjFRXb49A6pOY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788439435; c=relaxed/simple; bh=+qvEi8u0HGfYG1ro9sN67nupIzmXCB2hRfGWW7QmDOg=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=hFnYa7sTYfpDcOQRXLhLiCi1sEmBfVgvsr6oIJro2BjhxVwAUmJQsn651gxIOS3AfyaVibwK86SgVbUfbzlaN4XcPddw5AB0fvvGxWT8djoNxTIO4mUSGZpQIdw7x8Psal8mD4pGI6iGw6WHiqkoTzQuyLzzOAjTqMbCbwPED/w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tL1yfZQ5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="tL1yfZQ5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3A4A1F000E9; Thu, 3 Sep 2026 12:43:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788439434; bh=02GjXr4H/VpnggSjms2lT8FsCABctWx5kCl27qT8zyM=; h=Subject:To:Cc:From:Date; b=tL1yfZQ5hrceI8Ssux4eAXHfZjtyvqOowscLzn8yWrEl5w1Oasc9s6n0hqty4cuPi kSmRx+3PmlOMwUf25+D1fgPysU4+ZuelZK+5hhjiGujt2vlUEOyVxPGnypbjak3lnt QW8j0Q41e5+jnJbFwxzijhg+qep0MFfRTDZRjhXk= Subject: FAILED: patch "[PATCH] rust: bug: prevent dead_code warning from warn_on!'s flags" failed to apply to 6.18-stable tree To: fujita.tomonori@gmail.com,ojeda@kernel.org Cc: From: Date: Thu, 03 Sep 2026 12:42:47 +0200 Message-ID: <2026090347-reformat-saddled-eea6@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x e66cfc29e0d06fec34c06bb40d4d281f595677b1 # git commit -s git send-email --to '' --in-reply-to '2026090347-reformat-saddled-eea6@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e66cfc29e0d06fec34c06bb40d4d281f595677b1 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Sat, 1 Aug 2026 11:48:41 +0900 Subject: [PATCH] rust: bug: prevent dead_code warning from warn_on!'s flags constant Fix the following dead_code warning on some configurations in an atomic development branch: warning: constant `WARN_ON_FLAGS` is never used --> linux/rust/kernel/bug.rs:126:19 | 126 | const WARN_ON_FLAGS: u32 = $crate::bug::bugflag_taint($crate::bindings::TAINT_WARN); | ^^^^^^^^^^^^^ | ::: linux/rust/kernel/sync/srcu.rs:106:12 | 106 | if crate::warn_on!( | ____________- 107 | | // SAFETY: By the type invariants, `self` contains a valid and pinned `struct srcu_struct` 108 | | // and `srcu_readers_active()` only checks the active reader count. 109 | | unsafe { bindings::srcu_readers_active(ptr) } 110 | | ) { | |_________- in this macro invocation | = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default = note: this warning originates in the macro `crate::warn_on` (in Nightly builds, run with -Z macro-backtrace for more info) The warn_on! macro always defines a WARN_ON_FLAGS constant and hands it to warn_flags!. On configurations where warn_flags! does not reference its flags argument (the LOONGARCH/ARM variant, which only calls WARN_ON(), and the !CONFIG_BUG no-op variant), the constant is left unused and triggers a dead_code warning. warn_flags! is the macro that accepts (and here discards) the flags argument, so make it responsible for the argument it drops. Also rename `_COND_STR` to `COND_STR` and consume `$file` for consistency. Fixes: dff64b072708 ("rust: Add warn_on macro") Signed-off-by: FUJITA Tomonori Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260801024841.786664-1-tomo@flapping.org [ Added newlines. - Miguel ] Signed-off-by: Miguel Ojeda diff --git a/rust/kernel/bug.rs b/rust/kernel/bug.rs index ed943960f851..a09e6c9b314e 100644 --- a/rust/kernel/bug.rs +++ b/rust/kernel/bug.rs @@ -53,6 +53,10 @@ macro_rules! warn_flags { ($file:expr, $flags:expr) => { const FLAGS: u32 = $crate::bindings::BUGFLAG_WARNING | $flags; + if false { + _ = $file; + } + // SAFETY: // - `flags` and `size` are all compile-time constants, preventing // any invalid memory access. @@ -76,6 +80,10 @@ macro_rules! warn_flags { #[cfg(all(CONFIG_BUG, CONFIG_UML))] macro_rules! warn_flags { ($file:expr, $flags:expr) => { + if false { + _ = $file; + } + // SAFETY: It is always safe to call `warn_slowpath_fmt()` // with a valid null-terminated string. unsafe { @@ -94,6 +102,11 @@ macro_rules! warn_flags { #[cfg(all(CONFIG_BUG, any(CONFIG_LOONGARCH, CONFIG_ARM)))] macro_rules! warn_flags { ($file:expr, $flags:expr) => { + if false { + _ = $file; + _ = $flags; + } + // SAFETY: It is always safe to call `WARN_ON()`. unsafe { $crate::bindings::WARN_ON(true) } }; @@ -103,7 +116,12 @@ macro_rules! warn_flags { #[doc(hidden)] #[cfg(not(CONFIG_BUG))] macro_rules! warn_flags { - ($file:expr, $flags:expr) => {}; + ($file:expr, $flags:expr) => { + if false { + _ = $file; + _ = $flags; + } + }; } #[doc(hidden)] @@ -118,14 +136,14 @@ macro_rules! warn_on { let cond = $cond; #[cfg(CONFIG_DEBUG_BUGVERBOSE_DETAILED)] - const _COND_STR: &str = concat!("[", stringify!($cond), "] ", file!()); + const COND_STR: &str = concat!("[", stringify!($cond), "] ", file!()); #[cfg(not(CONFIG_DEBUG_BUGVERBOSE_DETAILED))] - const _COND_STR: &str = file!(); + const COND_STR: &str = file!(); if cond { const WARN_ON_FLAGS: u32 = $crate::bug::bugflag_taint($crate::bindings::TAINT_WARN); - $crate::warn_flags!(_COND_STR, WARN_ON_FLAGS); + $crate::warn_flags!(COND_STR, WARN_ON_FLAGS); } cond }};