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[13.59.0.164]) by smtp.gmail.com with ESMTPSA id b16-20020a05620a04f000b0069fd57d435fsm1127548qkh.101.2022.05.13.04.08.57 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 13 May 2022 04:08:59 -0700 (PDT) From: Schspa Shi To: rafael@kernel.org, viresh.kumar@linaro.org Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, schspa@gmail.com Subject: [PATCH v5 1/2] cpufreq: Abort show/store for half initialized policy Date: Fri, 13 May 2022 19:08:47 +0800 Message-Id: <20220513110848.20204-1-schspa@gmail.com> X-Mailer: git-send-email 2.29.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org If policy initialization fails after the sysfs files are created, there is a possibility that we may end up running show()/store() callbacks for half initialized policies, which may have unpredictable outcomes. Abort show/store in such a case by making sure the policy is active. Also inactivate the policy on such failures. Signed-off-by: Schspa Shi --- Changelog: v1 -> v2: - Fix bad critical region enlarge which causes uninitialized unlock. - Move cpumask_clear(policy->cpus); before out_offline_policy v2 -> v3: - Remove the missed down_write() before cpumask_and(policy->cpus, policy->cpus, cpu_online_mask); v3 -> v4: - Seprate to two patchs. - Add policy_is_inactive check before sysfs access v4 -> v5: - Change the commit message as Viresh advised. - Initialize ret to -EBUSY to get rid of the else part. --- drivers/cpufreq/cpufreq.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 80f535cc8a75..ba73be6f0490 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -947,13 +947,14 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf) { struct cpufreq_policy *policy = to_policy(kobj); struct freq_attr *fattr = to_attr(attr); - ssize_t ret; + ssize_t ret = -EBUSY; if (!fattr->show) return -EIO; down_read(&policy->rwsem); - ret = fattr->show(policy, buf); + if (likely(!policy_is_inactive(policy))) + ret = fattr->show(policy, buf); up_read(&policy->rwsem); return ret; @@ -964,7 +965,7 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, { struct cpufreq_policy *policy = to_policy(kobj); struct freq_attr *fattr = to_attr(attr); - ssize_t ret = -EINVAL; + ssize_t ret = -EBUSY; if (!fattr->store) return -EIO; @@ -978,7 +979,8 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, if (cpu_online(policy->cpu)) { down_write(&policy->rwsem); - ret = fattr->store(policy, buf, count); + if (likely(!policy_is_inactive(policy))) + ret = fattr->store(policy, buf, count); up_write(&policy->rwsem); } @@ -1533,6 +1535,7 @@ static int cpufreq_online(unsigned int cpu) for_each_cpu(j, policy->real_cpus) remove_cpu_dev_symlink(policy, get_cpu_device(j)); + cpumask_clear(policy->cpus); up_write(&policy->rwsem); out_offline_policy: