* Patch "thermal: cpu_cooling: don't call kcalloc() under rcu_read_lock" has been added to the 4.2-stable tree
@ 2015-10-17 22:04 gregkh
0 siblings, 0 replies; only message in thread
From: gregkh @ 2015-10-17 22:04 UTC (permalink / raw)
To: javi.merino, edubezval, gregkh, rui.zhang; +Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
thermal: cpu_cooling: don't call kcalloc() under rcu_read_lock
to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
thermal-cpu_cooling-don-t-call-kcalloc-under-rcu_read_lock.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From 459ac37506d195713b5e82271a2ac44a777e47df Mon Sep 17 00:00:00 2001
From: Javi Merino <javi.merino@arm.com>
Date: Mon, 17 Aug 2015 19:21:42 +0100
Subject: thermal: cpu_cooling: don't call kcalloc() under rcu_read_lock
From: Javi Merino <javi.merino@arm.com>
commit 459ac37506d195713b5e82271a2ac44a777e47df upstream.
build_dyn_power_table() allocates the power table while holding
rcu_read_lock. kcalloc using GFP_KERNEL may sleep, so it can't be
called in an RCU read-side path.
Move the rcu protection to the part of the function that really needs
it: the part that handles the dev_pm_opp pointer received from
dev_pm_opp_find_freq_ceil(). In the unlikely case that there is an OPP
added to the cpu while this function is running, return -EAGAIN.
Fixes: c36cf0717631 ("thermal: cpu_cooling: implement the power cooling device API")
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/thermal/cpu_cooling.c | 47 ++++++++++++++++++++----------------------
1 file changed, 23 insertions(+), 24 deletions(-)
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -262,7 +262,9 @@ static int cpufreq_thermal_notifier(stru
* efficiently. Power is stored in mW, frequency in KHz. The
* resulting table is in ascending order.
*
- * Return: 0 on success, -E* on error.
+ * Return: 0 on success, -EINVAL if there are no OPPs for any CPUs,
+ * -ENOMEM if we run out of memory or -EAGAIN if an OPP was
+ * added/enabled while the function was executing.
*/
static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
u32 capacitance)
@@ -270,11 +272,9 @@ static int build_dyn_power_table(struct
struct power_table *power_table;
struct dev_pm_opp *opp;
struct device *dev = NULL;
- int num_opps = 0, cpu, i, ret = 0;
+ int num_opps = 0, cpu, i;
unsigned long freq;
- rcu_read_lock();
-
for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
dev = get_cpu_device(cpu);
if (!dev) {
@@ -284,24 +284,20 @@ static int build_dyn_power_table(struct
}
num_opps = dev_pm_opp_get_opp_count(dev);
- if (num_opps > 0) {
+ if (num_opps > 0)
break;
- } else if (num_opps < 0) {
- ret = num_opps;
- goto unlock;
- }
+ else if (num_opps < 0)
+ return num_opps;
}
- if (num_opps == 0) {
- ret = -EINVAL;
- goto unlock;
- }
+ if (num_opps == 0)
+ return -EINVAL;
power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
- if (!power_table) {
- ret = -ENOMEM;
- goto unlock;
- }
+ if (!power_table)
+ return -ENOMEM;
+
+ rcu_read_lock();
for (freq = 0, i = 0;
opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
@@ -309,6 +305,11 @@ static int build_dyn_power_table(struct
u32 freq_mhz, voltage_mv;
u64 power;
+ if (i >= num_opps) {
+ rcu_read_unlock();
+ return -EAGAIN;
+ }
+
freq_mhz = freq / 1000000;
voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
@@ -326,18 +327,16 @@ static int build_dyn_power_table(struct
power_table[i].power = power;
}
- if (i == 0) {
- ret = PTR_ERR(opp);
- goto unlock;
- }
+ rcu_read_unlock();
+
+ if (i != num_opps)
+ return PTR_ERR(opp);
cpufreq_device->cpu_dev = dev;
cpufreq_device->dyn_power_table = power_table;
cpufreq_device->dyn_power_table_entries = i;
-unlock:
- rcu_read_unlock();
- return ret;
+ return 0;
}
static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,
Patches currently in stable-queue which might be from javi.merino@arm.com are
queue-4.2/thermal-cpu_cooling-don-t-call-kcalloc-under-rcu_read_lock.patch
queue-4.2/thermal-cpu_cooling-free-power-table-on-error-or-when-unregistering.patch
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2015-10-17 22:04 Patch "thermal: cpu_cooling: don't call kcalloc() under rcu_read_lock" has been added to the 4.2-stable tree gregkh
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