diff options
| author | Rohit Gupta <rohgup@codeaurora.org> | 2015-01-07 09:56:22 -0800 |
|---|---|---|
| committer | David Keitel <dkeitel@codeaurora.org> | 2016-03-23 21:22:24 -0700 |
| commit | 11ff15ea438cd77dafc54dde22a84f50a38ed4c2 (patch) | |
| tree | 54a9d93d17e0b5780db024f65fcc415b1bf5ce7a | |
| parent | a47233f55bf1097ef1685f0f08a0a95147e2f642 (diff) | |
soc: qcom: msm_perf: Fix a race condition in hotplug callback
msm_performance relies on userspace to initialize cluster related
variables such as num_clusters, managed_cpus etc. Once num_clusters
is set the cluster related data structures are initialized and
userspace is allowed to set them.
However there could be a race where between num_clusters being set
and the cluster data structures being allocated, there is a hotplug
activity which would invoke the hotplug callback which in turn tries
to access managed_cpus. managed_cpus might not have been allocated by
that time resulting in a NULL pointer access in the callback causing
kernel panic.
Change-Id: Ia40af624322a89e0c0f9598bf7eea059e6969ebe
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
| -rw-r--r-- | drivers/soc/qcom/msm_performance.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/drivers/soc/qcom/msm_performance.c b/drivers/soc/qcom/msm_performance.c index 38302c52202c..cc8faf63515c 100644 --- a/drivers/soc/qcom/msm_performance.c +++ b/drivers/soc/qcom/msm_performance.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2014, The Linux Foundation. All rights reserved. + * Copyright (c) 2014-2015, The Linux Foundation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 and @@ -33,6 +33,7 @@ struct cpu_hp { cpumask_var_t offlined_cpus; }; static struct cpu_hp **managed_clusters; +static bool clusters_inited; /* Work to evaluate the onlining/offlining CPUs */ struct delayed_work evaluate_hotplug_work; @@ -86,7 +87,7 @@ static int set_max_cpus(const char *buf, const struct kernel_param *kp) const char *cp = buf; int val; - if (!num_clusters) + if (!clusters_inited) return -EINVAL; while ((cp = strpbrk(cp + 1, ":"))) @@ -120,7 +121,7 @@ static int get_max_cpus(char *buf, const struct kernel_param *kp) { int i, cnt = 0; - if (!num_clusters) + if (!clusters_inited) return cnt; for (i = 0; i < num_clusters; i++) @@ -143,7 +144,7 @@ static int set_managed_cpus(const char *buf, const struct kernel_param *kp) int i, ret; struct cpumask tmp_mask; - if (!num_clusters) + if (!clusters_inited) return -EINVAL; ret = cpulist_parse(buf, &tmp_mask); @@ -168,7 +169,7 @@ static int get_managed_cpus(char *buf, const struct kernel_param *kp) { int i, cnt = 0; - if (!num_clusters) + if (!clusters_inited) return cnt; for (i = 0; i < num_clusters; i++) { @@ -195,7 +196,7 @@ static int get_managed_online_cpus(char *buf, const struct kernel_param *kp) struct cpumask tmp_mask; struct cpu_hp *i_cpu_hp; - if (!num_clusters) + if (!clusters_inited) return cnt; for (i = 0; i < num_clusters; i++) { @@ -498,6 +499,9 @@ static void __ref try_hotplug(struct cpu_hp *data) { unsigned int i; + if (!clusters_inited) + return; + pr_debug("msm_perf: Trying hotplug...%d:%d\n", num_online_managed(data->cpus), num_online_cpus()); @@ -590,6 +594,9 @@ static int __ref msm_performance_cpu_callback(struct notifier_block *nfb, unsigned int i; struct cpu_hp *i_hp = NULL; + if (!clusters_inited) + return NOTIFY_OK; + for (i = 0; i < num_clusters; i++) { if (cpumask_test_cpu(cpu, managed_clusters[i]->cpus)) { i_hp = managed_clusters[i]; @@ -656,6 +663,7 @@ static int init_cluster_control(void) INIT_DELAYED_WORK(&evaluate_hotplug_work, check_cluster_status); mutex_init(&managed_cpus_lock); + clusters_inited = true; return 0; } |