From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpbgbr1.qq.com (smtpbgbr1.qq.com [54.207.19.206]) (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 D1914146D41; Wed, 3 Apr 2024 12:53:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=54.207.19.206 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712148826; cv=none; b=ueKCy4iJPGJ7uJnL4jRcUMAlJIQwti4Fr1U704plMs27Ud8kvDdoI/+hKkF6yXTlAiJbvvKtZTRcSCK5n9mPVg8abNiAuPbLarAGTVmNoxSNSxeJkNvHckfxP52KgnRpua5hqUgcKq5IqzD3IuGdSLXGrzTZ0WkvKNRcpYqpTi8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712148826; c=relaxed/simple; bh=N3+jmIFBH0AMFXfes14ZXbK3viT/FuJyr71Pf7bRYZ4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=NzbgNJWejMgm4lOc+PHgtOr9JHkxNFK1jqfH7/5fw1KaKy7l1DjCAKcu8v/MdZUFrMXxQZVrKiMsb80u/4Ym9PHPwnTnlIViUgokfpYF4EHYgU9KZFDDcTEOPhu+7n8V4x0L4W7BsS35QG7WMX4hEFkXTjDhQPFYwCHapyq1T50= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=shingroup.cn; spf=pass smtp.mailfrom=shingroup.cn; arc=none smtp.client-ip=54.207.19.206 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=shingroup.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=shingroup.cn X-QQ-mid: bizesmtpsz15t1712148732tmp3f7 X-QQ-Originating-IP: hp+qVMYBYDmNau3Xt2Ytvj+o84IW5qbOYg/vMTzRtwI= Received: from localhost ( [112.0.147.175]) by bizesmtp.qq.com (ESMTP) with id ; Wed, 03 Apr 2024 20:52:10 +0800 (CST) X-QQ-SSF: 01400000000000704000000A0000000 X-QQ-FEAT: RrZlkntZBfm1BsuX7v8GUrYbIkXGb4KuNkFygyd4NSEyO16QA+4WGckn64RjL GQFe6dzbLRg7F9sTRNLUVBLFrP0rvndGl/KOt+YRefEqq0HIn54Nplviah+iU0q6GSWbAiD pqeN4oYni807Hlr+46rlinuWIzRgTDL7fVUzFfxltUv7p2S8/oFTKU3Ffrg4sqJ6WWEcO8k r+R/hy/qxUpId1vFasEipX+0GrflA4/30UbqmZlOmg1fNjf9v8bqI4/Xq8KjOTPQqVuefPj dVAn1+gr/nNR/cMYm4sQimsog4nuA2iK19IglEXwpv/IndcFXiqcTKxYvEO0SZ5eQDycOyD w8qI54wY5oChA3Cjnv/PrqAW4VXkXOpRHF62e7My9Zjh0Ezr4EeYac5ZhxuzRyEh8pOP5Ja uEYnDh0vp5Ribc1zi9ZB1bNKIdKO4Y2B X-QQ-GoodBg: 2 X-BIZMAIL-ID: 4140137453108644267 From: Dawei Li To: will@kernel.org, mark.rutland@arm.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk Cc: xueshuai@linux.alibaba.com, renyu.zj@linux.alibaba.com, yangyicong@hisilicon.com, jonathan.cameron@huawei.com, andersson@kernel.org, konrad.dybcio@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Dawei Li Subject: [PATCH v2 03/10] perf/arm-cmn: Avoid placing cpumask var on stack Date: Wed, 3 Apr 2024 20:51:02 +0800 Message-Id: <20240403125109.2054881-4-dawei.li@shingroup.cn> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20240403125109.2054881-1-dawei.li@shingroup.cn> References: <20240403125109.2054881-1-dawei.li@shingroup.cn> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtpsz:shingroup.cn:qybglogicsvrgz:qybglogicsvrgz5a-1 For CONFIG_CPUMASK_OFFSTACK=y kernel, explicit allocation of cpumask variable on stack is not recommended since it can cause potential stack overflow. Instead, kernel code should always use *cpumask_var API(s) to allocate cpumask var in config-neutral way, leaving allocation strategy to CONFIG_CPUMASK_OFFSTACK. But dynamic allocation in cpuhp's teardown callback is somewhat problematic for if allocation fails(which is unlikely but still possible): - If -ENOMEM is returned to caller, kernel crashes for non-bringup teardown; - If callback pretends nothing happened and returns 0 to caller, it may trap system into an in-consisitent/compromised state; Use newly-introduced cpumask_any_and_but() to address all issues above. It eliminates usage of temporary cpumask var in generic way, no matter how the cpumask var is allocated. Suggested-by: Mark Rutland Signed-off-by: Dawei Li --- drivers/perf/arm-cmn.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c index 7ef9c7e4836b..6bfb0c4a1287 100644 --- a/drivers/perf/arm-cmn.c +++ b/drivers/perf/arm-cmn.c @@ -1950,20 +1950,20 @@ static int arm_cmn_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_no struct arm_cmn *cmn; unsigned int target; int node; - cpumask_t mask; cmn = hlist_entry_safe(cpuhp_node, struct arm_cmn, cpuhp_node); if (cpu != cmn->cpu) return 0; node = dev_to_node(cmn->dev); - if (cpumask_and(&mask, cpumask_of_node(node), cpu_online_mask) && - cpumask_andnot(&mask, &mask, cpumask_of(cpu))) - target = cpumask_any(&mask); - else + + target = cpumask_any_and_but(cpumask_of_node(node), cpu_online_mask, cpu); + if (target >= nr_cpu_ids) target = cpumask_any_but(cpu_online_mask, cpu); + if (target < nr_cpu_ids) arm_cmn_migrate(cmn, target); + return 0; } -- 2.27.0