From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpbguseast3.qq.com (smtpbguseast3.qq.com [54.243.244.52]) (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 C18E7146A9D; Wed, 3 Apr 2024 12:54:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=54.243.244.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712148867; cv=none; b=Yme7K/fLW41G6ovto5zi7zID1tuJO86HkhnxxsOke9cDVMfHhWRy3emspl4V3AS9F6i562s8X0DjLeWvWz5yL8GLTiFKOoDmeII6UO2KaJMxrC35jRz3derOVNk6XgkUatrcUbOSQiL7s9p/owoMVdQj4NUEj067CTWvq2ES6XY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712148867; c=relaxed/simple; bh=DuvQOR4vsP78Wm5NVq8AOQUFUfQcm9T0pyka2X4Hhp4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Vq6wcXB8KZAtZJJN81wkzoGEFfLLDgjH0XHVU6MHPoRm9klc7lthG1QFd5ud4Rlu4lgdSXfrY1//AE9ZYGCngow4gWKsHYp4lFKM9++8wD8gf+3Kd3WAbuQf5aqsz7JyV/NtEP+ituFXmEUue0QMrxhQl0GROVWYwU2mLFO5yCg= 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=54.243.244.52 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: bizesmtpsz13t1712148751thjp14 X-QQ-Originating-IP: PN96WD6+s0f0fHNZoIaqwlrHcfY0nVQajJhi8FUfFuM= Received: from localhost ( [112.0.147.175]) by bizesmtp.qq.com (ESMTP) with id ; Wed, 03 Apr 2024 20:52:30 +0800 (CST) X-QQ-SSF: 01400000000000704000000A0000000 X-QQ-FEAT: zcLa5zqvhxgf/5JXWZ8twfXFCazlSAsrySVLuhjEZMYToUkKWNsAJmBBYfDe+ NsLkXC+chAgf1GKnj0xs+cjveEn376+2q5jqMLFhczeZpSps2N19LEoRD2EbL4GsthwKh2A ZyAM+BPRilAQekCh1hGwcIFu4x73e4p44a+fel0VgLqjLCpdTtAIDgjrdSd5diS1y57wy88 hDyTUongOVf12A2X/IV7LhSD94AniI9zUmfBXtROAXHdcHcYaWhLWsEoBZGrY2TnkpQM+My W/ls2X2G2eB/4CVV13mfkN8eKhXbh+2+EZslaoWjqF2Vpw/mamsDazphJq5suJJVWI/apJG AD/bzvFButsgFqs8fNhD38vhGupDFjLpN6Juab9D/+ynsLdXRwsXrr+Bl9JrApdbDjgOxeM oLfxxIRlYsInBfAA6uV2dWzExTT2ldHB X-QQ-GoodBg: 2 X-BIZMAIL-ID: 11098512972322688443 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 06/10] perf/dwc_pcie: Avoid placing cpumask var on stack Date: Wed, 3 Apr 2024 20:51:05 +0800 Message-Id: <20240403125109.2054881-7-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/dwc_pcie_pmu.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c index 957058ad0099..c5e328f23841 100644 --- a/drivers/perf/dwc_pcie_pmu.c +++ b/drivers/perf/dwc_pcie_pmu.c @@ -690,9 +690,8 @@ static int dwc_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_n { struct dwc_pcie_pmu *pcie_pmu; struct pci_dev *pdev; - int node; - cpumask_t mask; unsigned int target; + int node; pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node); /* Nothing to do if this CPU doesn't own the PMU */ @@ -702,10 +701,9 @@ static int dwc_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_n pcie_pmu->on_cpu = -1; pdev = pcie_pmu->pdev; node = dev_to_node(&pdev->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) { -- 2.27.0