The patch titled
cpufreq lock rewrite bugfix - Fix locking in cpufreq_get
has been added to the -mm tree. Its filename is
rewrite-lock-in-cpufreq-to-eliminate-cpufreq-hotplug-related-issues-fix.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: cpufreq lock rewrite bugfix - Fix locking in cpufreq_get
From: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Incremental bugfix to previous 3 patch patchset of cpufreq lock rewrite.
There was one code path in cpufreq_get, that was using the write lock
in place of read and also potential recursive lock with sysfs
interface of cpuinfo_cur_freq.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Gautham R Shenoy <ego@xxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Cc: Gautham R Shenoy <ego@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/cpufreq/cpufreq.c | 46 +++++++++++++++++++++---------------
1 files changed, 28 insertions(+), 18 deletions(-)
diff -puN drivers/cpufreq/cpufreq.c~rewrite-lock-in-cpufreq-to-eliminate-cpufreq-hotplug-related-issues-fix drivers/cpufreq/cpufreq.c
--- a/drivers/cpufreq/cpufreq.c~rewrite-lock-in-cpufreq-to-eliminate-cpufreq-hotplug-related-issues-fix
+++ a/drivers/cpufreq/cpufreq.c
@@ -101,6 +101,7 @@ EXPORT_SYMBOL_GPL(unlock_policy_rwsem_wr
/* internal prototypes */
static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event);
+static unsigned int __cpufreq_get(unsigned int cpu);
static void handle_update(struct work_struct *work);
/**
@@ -488,7 +489,7 @@ store_one(scaling_max_freq,max);
static ssize_t show_cpuinfo_cur_freq (struct cpufreq_policy * policy,
char *buf)
{
- unsigned int cur_freq = cpufreq_get(policy->cpu);
+ unsigned int cur_freq = __cpufreq_get(policy->cpu);
if (!cur_freq)
return sprintf(buf, "<unknown>");
return sprintf(buf, "%u\n", cur_freq);
@@ -1074,25 +1075,13 @@ unsigned int cpufreq_quick_get(unsigned
EXPORT_SYMBOL(cpufreq_quick_get);
-/**
- * cpufreq_get - get the current CPU frequency (in kHz)
- * @cpu: CPU number
- *
- * Get the CPU current (static) CPU frequency
- */
-unsigned int cpufreq_get(unsigned int cpu)
+static unsigned int __cpufreq_get(unsigned int cpu)
{
- struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+ struct cpufreq_policy *policy = cpufreq_cpu_data[cpu];
unsigned int ret_freq = 0;
- if (!policy)
- return 0;
-
if (!cpufreq_driver->get)
- goto out;
-
- if (unlikely(lock_policy_rwsem_write(cpu)))
- goto out;
+ return (ret_freq);
ret_freq = cpufreq_driver->get(cpu);
@@ -1106,11 +1095,32 @@ unsigned int cpufreq_get(unsigned int cp
}
}
- unlock_policy_rwsem_write(cpu);
+ return (ret_freq);
+}
+
+/**
+ * cpufreq_get - get the current CPU frequency (in kHz)
+ * @cpu: CPU number
+ *
+ * Get the CPU current (static) CPU frequency
+ */
+unsigned int cpufreq_get(unsigned int cpu)
+{
+ unsigned int ret_freq = 0;
+ struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+
+ if (!policy)
+ goto out;
+
+ if (unlikely(lock_policy_rwsem_read(cpu)))
+ goto out;
+
+ ret_freq = __cpufreq_get(cpu);
+
+ unlock_policy_rwsem_read(cpu);
out:
cpufreq_cpu_put(policy);
-
return (ret_freq);
}
EXPORT_SYMBOL(cpufreq_get);
_
Patches currently in -mm which might be from venkatesh.pallipadi@xxxxxxxxx are
git-cpufreq.patch
rewrite-lock-in-cpufreq-to-eliminate-cpufreq-hotplug-related-issues.patch
rewrite-lock-in-cpufreq-to-eliminate-cpufreq-hotplug-related-issues-fix.patch
ondemand-governor-restructure-the-work-callback.patch
ondemand-governor-use-new-cpufreq-rwsem-locking-in-work-callback.patch
-
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