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 6C385369D55 for ; Fri, 31 Jul 2026 20:30:54 +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=1785529856; cv=none; b=Pva/81zGevVrObdX0jYeKiquOc4a4dG7QW3Wyu/r7s/RjvUk63kUkxNhmI5AbuVrAFsubP84kroxQRvbAoJMuMj4o0pU9wPo44NFmd1g92DL2Hei/AGlHheZmnZLkfHB7boFdpcL/KpudW+J4iIb/6FKcV7vXatdniKpy0UXgZA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785529856; c=relaxed/simple; bh=DDKCSBmWdh69FjGpE3KtoKKl8diHs5FB1tKxxEDIwtY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D9rXD/CcMcCTenkVznc8Ns9jLN+fwpDtHKRd6LirtLB1VDRVBG3H75sLJa2FEuyCNFaf9kMVIH0CNdpdd+ci9HhgV007X9fKCZFsUf6Dy1e3hAuy1QF+4fZV7sxVAvOXPmxp4t+9Ba4EXVluMXN++NLvZXs9XD3kbGdX/1OsHRs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=T/hbaPJ4; 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="T/hbaPJ4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F83D1F0155F; Fri, 31 Jul 2026 20:30:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785529853; bh=XDCFK0Pykwc7yJhmq8+Cu0tsCgs0jRR2+x2RB8Lxd70=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=T/hbaPJ45q7zs2zifUXRStZDCLGs5HlF9QIzPDWbPyb4FWgWR8qGnPf+uJ6/OBDv5 pwUon9jYMwOnQ35PjS7NtzZrcELqeNzvSsT175FVmvYitgoj/7pbpPpD9hxLgyZXH/ at3FXcD/Bwov7n8kMXIc/PUAJo/GWynXtweoNEg0yKT2PdTYn3UiSM2zxIPUUrq0Nv oURy1t1Qtv/eAfCMmMeVd1i84n7FuUJQlYyhKDJC9P7pQQuZvdFUYBoMC0CpnSuRxh jyaIoYpJj/aM8pAqhJ9sjwnV1Nb4BLOHV4EOfC4L7UmlXJmqvqyqmMQk4IlRjn4X5i SJc+LeEk/LKBA== Received: from phl-compute-06.internal (phl-compute-06.internal [10.202.2.46]) by mailfauth.phl.internal (Postfix) with ESMTP id AEC11F40077; Fri, 31 Jul 2026 16:30:52 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-06.internal (MEProxy); Fri, 31 Jul 2026 16:30:52 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTFIC2VVTLK13uDkALWshPgkkwS9DC5Q8ljHaA42IPRnmgkrxQSeK5HYsDRhN4GhLk 6Lg9dLbHgT0DH+qVaNoW+UUFxptAXHUIdqGwEJPczm0ywmTmF9/CSNIQrGZfaA0/SYDXt9 FCHeSX4ZePBeVl3Top6EjJd42yXsFqp+L0LPuLnabUXIo8fT3yX5hMg5WmOramFVWkXrXb dtjJi0qTpjt7TXVawGUwOyoJ/Q6jP1wNaVQH+6xYGS7UXVpHVglHDWcX7SjmpbiByeHS7C oLMM3JHkGXdP7WkAt31sGvl3IAmYfCODupTHvovIO6+oDBZmEBw2YefLw5AUKyninHXISS fcBtE/oYMBzM/w4XXdH/a5eaaRY1NV57i2omU3LHbqUblqPHtNVtoFNc+U3a0UA2khKoQp ZcuvCggAZ8WU9KZiPN3M5l0Vf5AG8lSohqpQXwbEe+EnT3a3fC3f+hT55Tj8i6/P4aBCZz GZhzJOE9yx1tCkUrpU0MBWhBNvnlF3OhZdTcXtvkpeOmTia5KwxMsi2qrl6EENEkT2QF2A uOWKtM5Ftuo66Ouox10iJQG2RaTEYmCP4nqpafXKZ3B70Z6aTXz3dC3Ks/8/xYuX0uCCss 8osp5gC0z6GKsP6MowYZL7nF8XFW2CpD2ena+A3Fn6b/k1BhhtqnYLX9alJg X-ME-Proxy: Feedback-ID: i8dbe485b:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 31 Jul 2026 16:30:52 -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 09/24] sched: Avoid signed comparison of preempt_count() in __cant_migrate() Date: Fri, 31 Jul 2026 13:30:10 -0700 Message-ID: <20260731203031.13679-10-boqun@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260731203031.13679-1-boqun@kernel.org> References: <20260731203031.13679-1-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 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 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)