From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpbgeu1.qq.com (smtpbgeu1.qq.com [52.59.177.22]) (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 BC0771482EC; Wed, 3 Apr 2024 12:53:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.59.177.22 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712148831; cv=none; b=jdXtfhxornDM5N7ob6xBCleVIOlcAASf8ai9U3Eo5ZSzjOO7kdfnPQ3H4P20X22xRv1yhZQd5Bdi3ew+P8GX/yTudnpbKsn0Qv56I1h5Ze45U9kXuNBLMWOfKlnCam4Yj1GmtQkKJSgPNY+nKLVtROsJeak/7BAGuhMdom+fu7A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712148831; c=relaxed/simple; bh=+44ocduMZ3arrVTyEvNGTfJn/pXNlZB4i16mdgLoFoY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=qk/yc9V6ECXRJhb/hXPI9FR0RJ54nFHQtjN0ucKt7xnK54lyXG1XLIIpv6lowKFOk9CsM4c9FRaHHKE3fCucII7Q5x5hgXMxs87O5wpbxUvu8TCs9ojPV9QSLluA+b6M+I1dAs6qyJrwuIsxB8CPS3yw+/OILl47KHRlwBZ7L8U= 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=52.59.177.22 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: bizesmtpsz5t1712148745t2zdelq X-QQ-Originating-IP: gtG85rrBFgYquVhBEXaQuedD1lYsKNbDnucmL+QbTUs= Received: from localhost ( [112.0.147.175]) by bizesmtp.qq.com (ESMTP) with id ; Wed, 03 Apr 2024 20:52:23 +0800 (CST) X-QQ-SSF: 01400000000000704000000A0000000 X-QQ-FEAT: 3M0okmaRx3hYBn6c6xv94OOmj7QRwjjI90PZMYk07rq6fUKYPq7jtfpesKrxM Hp/NCAse2sa30t5lFPhi4nzJDvtpqAREDZEm9kXuZkZBS54HuzXSTNSOoqy+N7OMGmwZJvB W4N/IGrBxUN2fvl664QjB8Nn2vfTBlWIpxRgfSormkTkhdKMO/jcas8amuGmvm04xhg3JSV GveXZ3D3mDREigPfWnjS+QZuH1I4fZz2QQbba9y4ssVNmO7eka9dFoEPA3d8nZtXlUfC4c6 A/9fdw9FWHqe/O7A13cNIGAhKa/a14mzCAXCc9BTO2seoQFWrVqVRfqFZu8wNV6hlamFZnK SgfFscX3PpNOc+ZCkoVTmrJtTuqoNuht8yQd+/JeuhBz2e9W1wGkyCbwwmommR9Au9KdFWq GQcGDvL6aPh2ZQeszSbdeH0WMml+cW0m X-QQ-GoodBg: 2 X-BIZMAIL-ID: 8972781227681254528 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 05/10] perf/arm_dsu: Avoid placing cpumask var on stack Date: Wed, 3 Apr 2024 20:51:04 +0800 Message-Id: <20240403125109.2054881-6-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_dsu_pmu.c | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-) diff --git a/drivers/perf/arm_dsu_pmu.c b/drivers/perf/arm_dsu_pmu.c index bae3ca37f846..adc0bbb5fafe 100644 --- a/drivers/perf/arm_dsu_pmu.c +++ b/drivers/perf/arm_dsu_pmu.c @@ -230,15 +230,6 @@ static const struct attribute_group *dsu_pmu_attr_groups[] = { NULL, }; -static int dsu_pmu_get_online_cpu_any_but(struct dsu_pmu *dsu_pmu, int cpu) -{ - struct cpumask online_supported; - - cpumask_and(&online_supported, - &dsu_pmu->associated_cpus, cpu_online_mask); - return cpumask_any_but(&online_supported, cpu); -} - static inline bool dsu_pmu_counter_valid(struct dsu_pmu *dsu_pmu, u32 idx) { return (idx < dsu_pmu->num_counters) || @@ -827,14 +818,16 @@ static int dsu_pmu_cpu_online(unsigned int cpu, struct hlist_node *node) static int dsu_pmu_cpu_teardown(unsigned int cpu, struct hlist_node *node) { - int dst; - struct dsu_pmu *dsu_pmu = hlist_entry_safe(node, struct dsu_pmu, - cpuhp_node); + struct dsu_pmu *dsu_pmu; + unsigned int dst; + + dsu_pmu = hlist_entry_safe(node, struct dsu_pmu, cpuhp_node); if (!cpumask_test_and_clear_cpu(cpu, &dsu_pmu->active_cpu)) return 0; - dst = dsu_pmu_get_online_cpu_any_but(dsu_pmu, cpu); + dst = cpumask_any_and_but(&dsu_pmu->associated_cpus, + cpu_online_mask, cpu); /* If there are no active CPUs in the DSU, leave IRQ disabled */ if (dst >= nr_cpu_ids) return 0; -- 2.27.0