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 B866740586A; Fri, 5 Jun 2026 05:41:50 +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=1780638113; cv=none; b=URH8KyQTrQuMaxRZLHg+YXExCJiR1k6I0mYacCBAFB+nT2CKDcLPZASUmB5EJNTccntSdL3jh/kWgZ2GU0vrlTLnYDyndK0eB9jh9oK1/IlWQhosnL1ZQOfrn9e2Jlz/6ttJgq8L2fwZ3awcfJLIgPoykwxLqykNhMang8SfJJQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780638113; c=relaxed/simple; bh=EEF7M1M56zwwhTGXRepJ6Df3YmQZblYNwV9p/gbKAlY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=H0iaSxusWlzCnDVFl56XSAZmA1CIL021MiqHYuAH96xBPocnVXauTQgt2G7tdtdyegWa1li+cdwAceBAD8uZaH5uOATkLYhwykiaRysD2actu/qHsWTC+FquKxc4An1G08/IzBL8g8cBakngPp1/TDp1emEcCHQbqRVrvDqweRo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bZoiokMs; 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="bZoiokMs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2D561F008A1; Fri, 5 Jun 2026 05:41:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780638110; bh=pFJVb0XMzYiDkWRfHTccDmCKdRjygd0kE9XeKrNBbFM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bZoiokMslLIjN2vzT4TIFP69TYMaOYz/Rs8dBvcDVfh8znI5PyQZZ/MI6h3qmF8+J b8FKP5o9Y5Kg/pfhZicPqaKRm0YEhlLb4BD1sbQoJ5K2gC2cU0VzVIDPO8b+U58q5q FA8v9c06PZwWgVmOt8V3eDYVr3o5b+hTQ76ys3oo2xVbh+ItLecG0caDz97MCKImn5 aWP5IjVIw+HArzbUh8huLosDMiMAchoYiheeZ0nQI8sPAZsiMSij+Kw6ccKBJJnEVR r+r8gSfJl4Q+t6jJrcUyMG8SwUAG3vrB+lzxKaGcs3tIy9tn7JnJInhrAQ1pm8GeuL f9ui1biHAMgQw== Received: from phl-compute-04.internal (phl-compute-04.internal [10.202.2.44]) by mailfauth.phl.internal (Postfix) with ESMTP id 0C7FEF40068; Fri, 5 Jun 2026 01:41:48 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-04.internal (MEProxy); Fri, 05 Jun 2026 01:41:48 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTFG0WJa+84B5ZLakFCJusLrHx60u/M2e4tgb8vvSWGQWHXMFZeKktHow9VrFaQhwL 60vkPLe/GHUXrF9uQjn9EtWhYCiYebO343SXKkauObGNd0gaHEDMGyAUdMEWI3xvV5+MXM Y5XIGIH+RCj/YpjPsc3XHQUzqyjdf8JDGbXE7uRDsVlh2adsQWoVoEG+11Li6tmpxBjo+n GbGHXxcMsG5BC+v/PWXz65OFiJmnJTn18gjrdwmPsAQA0I/XEj3HJhBv36WGSvCgORqSG4 pkDfFOinWXk05Px2n3ZYSDFusuNrnah7Cqk2jZsViR99U7a3ccatK3SGLf/zDxH9xSS8Bx NJDPeypZR+UT9k/SqltVTKWiw30nGSTGNtoJTZhFEw535tbPvHx+fxLRs5Z4ou1e4WVvr5 fjYq3d0sE8tdFC8joSEqZ+Uo7JwQns/hPHB/VwsR4PvGZtpea1JqcCyFMlPJgyyx8EE4pv jvz4p8DgyUVrtSDfrlYz1plh7KfMMU0jKMO8SRKIOnV1u69YyXD/2yFnyoWy2B1n65QqoC B93ANNq/Xa14drwvS5S7v3OdLu8oSVLylHkLZ+VvgmcmCDl4meFSxlGDWOyi5EBtb/cBbE fuJpgrv2lvgm+etFqRsdjN9nNR9q729Z/AtVZ6SmDmULleejLzV6BAMpyAjQ X-ME-Proxy: Feedback-ID: i8dbe485b:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 5 Jun 2026 01:41:46 -0400 (EDT) From: Boqun Feng To: Peter Zijlstra Cc: Catalin Marinas , Will Deacon , Jonas Bonn , Stefan Kristiansson , Stafford Horne , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Arnd Bergmann , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Boqun Feng , Waiman Long , Andrew Morton , Andrii Nakryiko , Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Shuah Khan , Miguel Ojeda , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Jinjie Ruan , Lyude Paul , Thomas Huth , Sohil Mehta , Pawan Gupta , Sean Christopherson , Nikunj A Dadhania , "Xin Li (Intel)" , Joel Fernandes , Andy Shevchenko , Randy Dunlap , Yury Norov , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-s390@vger.kernel.org, linux-arch@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, rust-for-linux@vger.kernel.org Subject: [PATCH v3 09/13] sched: Avoid signed comparison of preempt_count() in __cant_migrate() Date: Thu, 4 Jun 2026 22:41:24 -0700 Message-ID: <20260605054128.5925-10-boqun@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260605054128.5925-1-boqun@kernel.org> References: <20260605054128.5925-1-boqun@kernel.org> Precedence: bulk X-Mailing-List: linux-arch@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 return 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 checking 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 75dba7cc09bd..636e6a15f104 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -9207,7 +9207,7 @@ 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) -- 2.51.0