[PATCH] thermal: cpu_cooling: fix handling of invalid frequency table entries

From: Andrew Bresticker
Date: Tue Apr 09 2013 - 17:57:08 EST


get_cpu_frequency() goes into an infinite loop if any of the entries
in the CPU frequency table are invalid. This patch fixes that case
and, with a separate counter for frequency levels, ensures that the
n-th valid frequency level is returned.

Signed-off-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
---
drivers/thermal/cpu_cooling.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 836828e..e6db441 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -124,14 +124,14 @@ static int is_cpufreq_valid(int cpu)
static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
{
int ret = 0, i = 0;
- unsigned long level_index;
+ unsigned long level_index = 0;
bool descend = false;
struct cpufreq_frequency_table *table =
cpufreq_frequency_get_table(cpu);
if (!table)
return ret;

- while (table[i].frequency != CPUFREQ_TABLE_END) {
+ for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
continue;

@@ -143,24 +143,25 @@ static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
}

/*return if level matched and table in descending order*/
- if (descend && i == level)
+ if (descend && level_index == level)
return table[i].frequency;
- i++;
+ level_index++;
}
i--;
+ level_index--;

- if (level > i || descend)
+ if (level > level_index || descend)
return ret;
- level_index = i - level;
+ level = level_index - level;

/*Scan the table in reverse order and match the level*/
- while (i >= 0) {
+ for (; i >= 0; i--) {
if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
continue;
/*return if level matched*/
- if (i == level_index)
+ if (level_index == level)
return table[i].frequency;
- i--;
+ level_index--;
}
return ret;
}
--
1.8.1.3

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