From nobody Tue Sep 29 09:09:01 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 183A83A7F6F; Mon, 10 Aug 2026 08:57:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786352266; cv=none; b=Bi+SNArbKSqD61k7ywIb7szKjN500+pCVuFXiZ+Zb775Cwriif36ACiwmkHhi2RZ1yz7w5QbMCx4FJ2sCGxyRWv2SrWaTPZ0GDP0y2SClmcT4iUisUbtvg0aTsNBEZvNGeOhXA2+Boi35dO7faWBsX1cc/0YajBF/rkVmmLUdGE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786352266; c=relaxed/simple; bh=JErDzbo4tEiyN7gE1P7VltJu3jYgbeD801KJmu5o9hk=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=K7HBrKcLR7dkwyk4QXb+bQgwv0w7hIzOYcUEDg9wtobZsflZsfbpEEWyPV1nXPV7FFgJXPFlpSsh5pk0byH+g8MMc797QuaQHN6zANvT1DUgEGYcbHztwj8cIfl0ujwZywuwxCild3XIzUF2O6aDFQtWSslvmuLhnN8ujJiZWgU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=bIbdWikJ; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=U6P2N9n5; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="bIbdWikJ"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="U6P2N9n5" Date: Mon, 10 Aug 2026 08:57:40 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1786352262; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=H/h7fFriX4lE0Yi1ViWd7xD8dbeSyxwskpkuMbotdEU=; b=bIbdWikJ9EDKJHxSJUNfHYZyKkWsDXS5zjdHFgFbm+NV8RlLeat5d7uckZZ+NmeEPepAUn W4JNv3MxDYCTX0Ep8dkERWV0k0lMY0+cB248J90fuMoq2f2W8UtXnbt/9/uzUKWYRGvNXC kpliIsOvFp1ZCulodxRSsMlluAAtWZWjOvbuNVu/Ptmz0CV8Va+Lp6m51LU5J+vNEsTmYM rDRBmKwlA7wGxX4x2OEvciDDbc4TWyTjTfLHzVE5NsEm6jClimQxiSmx4hqlWwqkpFk5oW Q7/oB11Z3hIAjpf4+8brWqWMKacRo3EDuKPi7tE8HBfoGYUvYTK6FZ+BUFl1eg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1786352262; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=H/h7fFriX4lE0Yi1ViWd7xD8dbeSyxwskpkuMbotdEU=; b=U6P2N9n5/aH7n8M7Kn2FWFZUEnXpE73jwg+KpzJphwcnyao7Nevf/GKdvM5gY9j/OYioOe 8nmqj05D14kHmeAQ== From: "tip-bot2 for Boqun Feng" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] sched: Avoid signed comparison of preempt_count() in __cant_migrate() Cc: Boqun Feng , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20260804161447.84806-10-boqun@kernel.org> References: <20260804161447.84806-10-boqun@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <178635226091.442315.26965286051553571.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the locking/core branch of tip: Commit-ID: 560fcaa92ef983315023eb4ebfc1ebae1132fb2a Gitweb: https://git.kernel.org/tip/560fcaa92ef983315023eb4ebfc1ebae1= 132fb2a Author: Boqun Feng AuthorDate: Tue, 04 Aug 2026 09:14:31 -07:00 Committer: Peter Zijlstra CommitterDate: Mon, 10 Aug 2026 10:50:19 +02:00 sched: Avoid signed comparison of preempt_count() in __cant_migrate() 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 Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260804161447.84806-10-boqun@kernel.org --- 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 aa116da..9b3f176 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; =20 - if (preempt_count() > 0) + if (preempt_count()) return; =20 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)