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authorSudeep Holla <sudeep.holla@arm.com>2019-10-18 13:58:15 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-10-22 19:07:30 +0300
commit6941051d3028963c3b0b3fcdd0815f2b51b957bb (patch)
treef2838c99cbc57ffb008cc2736a8e431fb1eef0be /drivers/cpufreq
parent2aac8bdf7a0fbd3e2a34141d28b57a7e21482cf7 (diff)
downloadlinux-6941051d3028963c3b0b3fcdd0815f2b51b957bb.tar.xz
cpufreq: Cancel policy update work scheduled before freeing
Scheduled policy update work may end up racing with the freeing of the policy and unregistering the driver. One possible race is as below, where the cpufreq_driver is unregistered, but the scheduled work gets executed at later stage when, cpufreq_driver is NULL (i.e. after freeing the policy and driver). Unable to handle kernel NULL pointer dereference at virtual address 0000001c pgd = (ptrval) [0000001c] *pgd=80000080204003, *pmd=00000000 Internal error: Oops: 206 [#1] SMP THUMB2 Modules linked in: CPU: 0 PID: 34 Comm: kworker/0:1 Not tainted 5.4.0-rc3-00006-g67f5a8081a4b #86 Hardware name: ARM-Versatile Express Workqueue: events handle_update PC is at cpufreq_set_policy+0x58/0x228 LR is at dev_pm_qos_read_value+0x77/0xac Control: 70c5387d Table: 80203000 DAC: fffffffd Process kworker/0:1 (pid: 34, stack limit = 0x(ptrval)) (cpufreq_set_policy) from (refresh_frequency_limits.part.24+0x37/0x48) (refresh_frequency_limits.part.24) from (handle_update+0x2f/0x38) (handle_update) from (process_one_work+0x16d/0x3cc) (process_one_work) from (worker_thread+0xff/0x414) (worker_thread) from (kthread+0xff/0x100) (kthread) from (ret_from_fork+0x11/0x28) Fixes: 67d874c3b2c6 ("cpufreq: Register notifiers with the PM QoS framework") Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> [ rjw: Cancel the work before dropping the QoS requests ] Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 8478ff6f3045..48a224a6b178 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1268,6 +1268,9 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MIN,
&policy->nb_min);
+ /* Cancel any pending policy->update work before freeing the policy. */
+ cancel_work_sync(&policy->update);
+
if (policy->max_freq_req) {
/*
* CPUFREQ_CREATE_POLICY notification is sent only after