From: Dawei Li <dawei.li@shingroup.cn> 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 <dawei.li@shingroup.cn> Subject: [PATCH v2 10/10] perf/thunderx2: Avoid placing cpumask var on stack Date: Wed, 3 Apr 2024 20:51:09 +0800 [thread overview] Message-ID: <20240403125109.2054881-11-dawei.li@shingroup.cn> (raw) In-Reply-To: <20240403125109.2054881-1-dawei.li@shingroup.cn> 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 <mark.rutland@arm.com> Signed-off-by: Dawei Li <dawei.li@shingroup.cn> --- drivers/perf/thunderx2_pmu.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c index e16d10c763de..b3377b662ffc 100644 --- a/drivers/perf/thunderx2_pmu.c +++ b/drivers/perf/thunderx2_pmu.c @@ -932,9 +932,8 @@ static int tx2_uncore_pmu_online_cpu(unsigned int cpu, static int tx2_uncore_pmu_offline_cpu(unsigned int cpu, struct hlist_node *hpnode) { - int new_cpu; struct tx2_uncore_pmu *tx2_pmu; - struct cpumask cpu_online_mask_temp; + unsigned int new_cpu; tx2_pmu = hlist_entry_safe(hpnode, struct tx2_uncore_pmu, hpnode); @@ -945,11 +944,8 @@ static int tx2_uncore_pmu_offline_cpu(unsigned int cpu, if (tx2_pmu->hrtimer_callback) hrtimer_cancel(&tx2_pmu->hrtimer); - cpumask_copy(&cpu_online_mask_temp, cpu_online_mask); - cpumask_clear_cpu(cpu, &cpu_online_mask_temp); - new_cpu = cpumask_any_and( - cpumask_of_node(tx2_pmu->node), - &cpu_online_mask_temp); + new_cpu = cpumask_any_and_but(cpumask_of_node(tx2_pmu->node), + cpu_online_mask, cpu); tx2_pmu->cpu = new_cpu; if (new_cpu >= nr_cpu_ids) -- 2.27.0
WARNING: multiple messages have this Message-ID (diff)
From: Dawei Li <dawei.li@shingroup.cn> 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 <dawei.li@shingroup.cn> Subject: [PATCH v2 10/10] perf/thunderx2: Avoid placing cpumask var on stack Date: Wed, 3 Apr 2024 20:51:09 +0800 [thread overview] Message-ID: <20240403125109.2054881-11-dawei.li@shingroup.cn> (raw) In-Reply-To: <20240403125109.2054881-1-dawei.li@shingroup.cn> 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 <mark.rutland@arm.com> Signed-off-by: Dawei Li <dawei.li@shingroup.cn> --- drivers/perf/thunderx2_pmu.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c index e16d10c763de..b3377b662ffc 100644 --- a/drivers/perf/thunderx2_pmu.c +++ b/drivers/perf/thunderx2_pmu.c @@ -932,9 +932,8 @@ static int tx2_uncore_pmu_online_cpu(unsigned int cpu, static int tx2_uncore_pmu_offline_cpu(unsigned int cpu, struct hlist_node *hpnode) { - int new_cpu; struct tx2_uncore_pmu *tx2_pmu; - struct cpumask cpu_online_mask_temp; + unsigned int new_cpu; tx2_pmu = hlist_entry_safe(hpnode, struct tx2_uncore_pmu, hpnode); @@ -945,11 +944,8 @@ static int tx2_uncore_pmu_offline_cpu(unsigned int cpu, if (tx2_pmu->hrtimer_callback) hrtimer_cancel(&tx2_pmu->hrtimer); - cpumask_copy(&cpu_online_mask_temp, cpu_online_mask); - cpumask_clear_cpu(cpu, &cpu_online_mask_temp); - new_cpu = cpumask_any_and( - cpumask_of_node(tx2_pmu->node), - &cpu_online_mask_temp); + new_cpu = cpumask_any_and_but(cpumask_of_node(tx2_pmu->node), + cpu_online_mask, cpu); tx2_pmu->cpu = new_cpu; if (new_cpu >= nr_cpu_ids) -- 2.27.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2024-04-03 12:54 UTC|newest] Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-04-03 12:50 [PATCH v2 00/10] perf: Avoid placing cpumask var on stack Dawei Li 2024-04-03 12:50 ` Dawei Li 2024-04-03 12:51 ` [PATCH v2 01/10] cpumask: add cpumask_any_and_but() Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 12:51 ` [PATCH v2 02/10] perf/alibaba_uncore_drw: Avoid placing cpumask var on stack Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:16 ` Mark Rutland 2024-04-03 14:16 ` Mark Rutland 2024-04-03 12:51 ` [PATCH v2 03/10] perf/arm-cmn: " Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:23 ` Mark Rutland 2024-04-03 14:23 ` Mark Rutland 2024-04-03 12:51 ` [PATCH v2 04/10] perf/arm_cspmu: " Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:21 ` Mark Rutland 2024-04-03 14:21 ` Mark Rutland 2024-04-03 12:51 ` [PATCH v2 05/10] perf/arm_dsu: " Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:32 ` Mark Rutland 2024-04-03 14:32 ` Mark Rutland 2024-04-03 12:51 ` [PATCH v2 06/10] perf/dwc_pcie: " Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:33 ` Mark Rutland 2024-04-03 14:33 ` Mark Rutland 2024-04-03 12:51 ` [PATCH v2 07/10] perf/hisi_pcie: " Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:35 ` Mark Rutland 2024-04-03 14:35 ` Mark Rutland 2024-04-05 9:52 ` Jonathan Cameron 2024-04-05 9:52 ` Jonathan Cameron 2024-04-03 12:51 ` [PATCH v2 08/10] perf/hisi_uncore: " Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:35 ` Mark Rutland 2024-04-03 14:35 ` Mark Rutland 2024-04-05 9:53 ` Jonathan Cameron 2024-04-05 9:53 ` Jonathan Cameron 2024-04-03 12:51 ` [PATCH v2 09/10] perf/qcom_l2: " Dawei Li 2024-04-03 12:51 ` Dawei Li 2024-04-03 14:36 ` Mark Rutland 2024-04-03 14:36 ` Mark Rutland 2024-04-03 12:51 ` Dawei Li [this message] 2024-04-03 12:51 ` [PATCH v2 10/10] perf/thunderx2: " Dawei Li 2024-04-03 14:38 ` Mark Rutland 2024-04-03 14:38 ` Mark Rutland 2024-04-03 14:41 ` [PATCH v2 00/10] perf: " Mark Rutland 2024-04-03 14:41 ` Mark Rutland 2024-04-03 16:11 ` Dawei Li 2024-04-03 16:11 ` Dawei Li 2024-04-03 16:39 ` Yury Norov 2024-04-03 16:39 ` Yury Norov
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