From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.34 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793962579; b=MSds2D2KfFfJmBvL1VMOsMuON/7IxZJ5h6vJ4z0OPSW1yj70OywLZWYyg5/M0040HEB8 tQpK1stcvc82Fo/P8BopzhBSc17x4jZGLjS1VKmTMCHc9rVJFrJ1auUDLF6ifXl9jlpsV +XUCXysY5zu2kW1Bh09COWNpU2dKfBS6t+gxZc/IF55DTFIyNYu81zV45fovi77u/RRyS FBYp6UV1y6KRJQgxQs4t7CUNz6U2Uu1Q5XxaB0VwGjK5f1a77I3a8tQvj229mb61RRpy0 5fUrSXzE5cl6d418qOZNzM3QFdEshDcyhfP5sIWEIsH7GGZeJRJL0GWeO5rmyulKFkQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793962579; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-Id: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=IntcUjxwgNLtHOPR/YXFXE90UCsfrPbdVNTWrhH07h8=; b=YOWz2gaZbxJ7YSdx3e2Znb5uMUi/QxKlins8gbJav+FOx8zsFEdX9lruE9UuufybRNEC +a0VxDNRHlaf0tj5vhu7LUqVVmKFKHvSHUTgkaG4FQwYd2pnh/C3W/aWEnSvY+sPnshHT +q323D5sqL2iWdSjxpZmLMUwR+rzehKJmeUCHpPY5ywjNCxvfZ23xKkrXPl2gQ5hEK3en LPchHypuWkvKQvNgNyvW4On4yRs+xubboJGYeerg3OOZ4Ry8Bv4Dd6Zy6n92nGlrZzskZ ppcUNeZxvrmUVt/dvAK/jYuAYHW+S89aKsys0pcCTI/+Vw/bl3/U8PuDU9koCyghrmA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=AAJTPCjT; arc=none smtp.remote-ip=91.218.175.34 Received: from mta0.migadu.com (out-34.mta0.migadu.com [91.218.175.34]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 799E2606A331 for ; Fri, 6 Nov 2026 10:56:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 799E2606A331 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=AAJTPCjT X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=3jkfoR067/Flf47+e2LOQlU8r6Ck3Qy/GPAvsTLC2P0=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793962576; v=1; x=1794567376; b=AAJTPCjTta1oiiYfalVzhE1hn290tL3JxQZfv2lZ+0Sbnss58gj/MV4NMlSKPeCFQoNimngB 2JcdjLjASsxb6BJKJ3fghJJepdzM8uP1aA/zH2OSkZAZoyPM2XdpHm3t8NFtpVtOuM8uAjCGkfU pP5RrpG1v/teULXjH1DLryhQ= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 775cdc43aa869329; Fri, 06 Nov 2026 10:56:16 +0000 X-Mizu-Trace-ID: 775cdc43aa869329 X-Migadu-Flow: FLOW_OUT From: Ridong Chen To: Waiman Long , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Shuah Khan Cc: Ridong Chen , Chen Ridong , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Sashiko , Guopeng Zhang , Ridong Chen Subject: [PATCH v2 2/4] cpuset: add early empty cpumask check in partition_xcpus_add/del Date: Fri, 6 Nov 2026 18:55:36 +0800 Message-Id: <20261106105538.2915492-3-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261106105538.2915492-1-ridong.chen@linux.dev> References: <20261106105538.2915492-1-ridong.chen@linux.dev> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chen Ridong Add a check for an empty cpumask at the start of partition_xcpus_add() and partition_xcpus_del(). This allows the functions to return early, avoiding unnecessary computation when there is no work to be done. With these changes, partition_xcpus_add() and partition_xcpus_del() can be called even if xcpus is empty. The caller no longer needs to check whether xcpus is empty, eliminating many conditional statements. Signed-off-by: Chen Ridong Reviewed-by: Guopeng Zhang Signed-off-by: Ridong Chen --- kernel/cgroup/cpuset.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index cf38e8708ddd..85e5b529d144 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1315,10 +1315,13 @@ static void partition_xcpus_add(int new_prs, struct cpuset *parent, { WARN_ON_ONCE(new_prs < 0); lockdep_assert_held(&callback_lock); + + if (cpumask_empty(xcpus)) + return; + if (!parent) parent = &top_cpuset; - if (parent == &top_cpuset) cpumask_or(subpartitions_cpus, subpartitions_cpus, xcpus); @@ -1342,6 +1345,10 @@ static void partition_xcpus_del(int old_prs, struct cpuset *parent, { WARN_ON_ONCE(old_prs < 0); lockdep_assert_held(&callback_lock); + + if (cpumask_empty(xcpus)) + return; + if (!parent) parent = &top_cpuset; -- 2.34.1