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 A760F4749D5 for ; Tue, 4 Aug 2026 16:15:13 +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=1785860119; cv=none; b=VeRbSBO5FsQuP/B6GUUswfVBLJcW84cOArKkCO+z4sTV/btmdKoAY3Fw9K2HLfmxvM0od+C6jnvZzNRxsFp+q1G00ANf0nsRljf+Yb7YJTTgdOjoOyxcyz4iTftjp+2mSgz76V9gtx3Zq5fiLXBnBSdZXv+AT6Kfs+ti6iSAAyY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785860119; c=relaxed/simple; bh=gdX2/8yO0N7n17FlM8ctDDZ1lMRo6f/CFk/F/ffOAD4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jXDaDQnouQGd/obHB3oO/uaBHiOU+Nm5IfekaHrFfCONJZa5gd/eVSGzmCJ+DEN4x7WurxbdW4TO8q9WmpsFcDM2piTMct4JmEdwfvRpdnUFjhUbKHHsrDT/DD61Bn3QZ1BOdTZ1v4XNBtjVmgjS0O1uZoLErkpyqsQRCXhR5TM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Vbo5Fc3x; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Vbo5Fc3x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B1CA1F00ACF; Tue, 4 Aug 2026 16:15:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785860111; bh=uaMiBt5vafGBdINwxuR8k+kc9W7/u2yo8z9BluwAE/g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Vbo5Fc3xiyvVNnXaKZYLgOJiD573SdOdZCCuIzEH9LpoMIwFdiKCxYGEzj6zk2uah DMoJV8OStdVhObep1NyOcQfcAtDyUm8pleq9M9Pyrijy4AwlXZwfiCv2TTBptlI/YH FdA821vuw9v9hs2qDZfC2HS/Do8t6+u5BE1frMOduSov3DvAHkejg6MvY6TmXVtvmq FL92vzxQhWN/7vWa4lHB3LggTqWeJ6X5ydTyr+QMHOIBmXSw9INCLgqkD4cSoYjacq Eu9EMEJmbcnDtWGisRYgxiunE3Na6BG/HnFmN4sD/pGCeKVEN/zoXQGpjRzS41/vyy WjYAj6qyjo/sA== Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfauth.phl.internal (Postfix) with ESMTP id 78A21F40066; Tue, 4 Aug 2026 12:15:10 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-02.internal (MEProxy); Tue, 04 Aug 2026 12:15:10 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTFdfHSt+dGlSIgweIKZqd43ZIr2UVwMz+DLCV7Uxtqr2tWdjT0gNVbLG23y/ntMNr yg2u9xNueu4ZlCPesc7IGVMS6ZqisyNG2Hp2kDVIfbBL9QFp1F1pvbwsQcrNmamnsGJsZY AmMncETOYZEkhlG6T7JDS64AVGc7Ln4zXY6x3T0lHgb+OYvht9swwTIGsG7Xot0GJG9bWc fhVx9JgcfYh5ECBMh98FFx1XWl/VnjhK7S6I+ssCNmeXl+D6Do6MWM72zOvrRuLzi3YdIE +uwF6SMc7tQqt75yJIKNoQF+R4TbmXy2JAxyIWDxHsQYaXIqpYC7ilWb/r9+jjwAD2JcNX ZHW6YG9QXu50mMhrSTuVu5sHfh2gb0c7rW3JeGWGaD/0HvmORg07SFbFbH3Ybq6WCUTkJv LPQlEkSTsZlPCfG8f45vVU0jlIX/gCp5dSSXCj4KlsKgeEdVj7uHtnsXYoAhhrAOyNL4W5 ofxD+1xC6EXrxGrggTEvjUX7WwhHRdQp8w9lnfdBuSUUC5uExYHswUHnY+1r05+0BXad2v fwz23DqRQpz9LCzZ8dndZPpgWnOyjaMbcRH+O88Q6ZMgV+Ws7MiH02fUoXK4V9UITeX0Dd bqWIfGhEg7xuDLV1rff26bPb9TAoiD/tVo6qdsAm15Db8f8qfl1MXBwIwKMA X-ME-Proxy: Feedback-ID: i8dbe485b:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 4 Aug 2026 12:15:09 -0400 (EDT) From: Boqun Feng To: Peter Zijlstra Cc: "Ingo Molnar" , "Will Deacon" , "Boqun Feng" , "Waiman Long" , "Gary Guo" , "Alice Ryhl" , "Lyude Paul" , "Daniel Almeida" , =?UTF-8?q?Onur=20=C3=96zkan?= , "Miguel Ojeda" , "Danilo Krummrich" , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org Subject: [PATCH v4 09/17] sched: Avoid signed comparison of preempt_count() in __cant_migrate() Date: Tue, 4 Aug 2026 09:14:31 -0700 Message-ID: <20260804161447.84806-10-boqun@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260804161447.84806-1-boqun@kernel.org> References: <20260804161447.84806-1-boqun@kernel.org> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently preempt_count() is always a non-negative int on all archs (PREEMPT_NEED_RESCHED archs will mask out the MSB when returning preempt_count()), hence the checking in __cant_migrate() is in fact just checking whether preempt_count() is 0 or not. In a future change, we are going to use all the 32 bits of preempt_count(), which would make negative int values possible from preempt_count(). Therefore convert the "> 0" comparison into a zero check to prepare for the future change. No functional changes are intended. Signed-off-by: Boqun Feng --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index aa116daf21bd..9b3f1764fa9e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -9241,7 +9241,7 @@ void __cant_migrate(const char *file, int line) if (!IS_ENABLED(CONFIG_PREEMPT_COUNT)) return; - if (preempt_count() > 0) + if (preempt_count()) return; if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) -- 2.50.1 (Apple Git-155)