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authorGautham R. Shenoy <ego@linux.vnet.ibm.com>2017-11-07 11:09:29 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-11-09 01:41:25 +0300
commitf7bc9b209e27c0b617378400136cc663a6314d0c (patch)
treeb54c5275965162f7df59cdf84c0c1ff82c7f87b4 /drivers/cpufreq
parent0011c6da99ddc428a35456d5819d6e476005f6f2 (diff)
downloadlinux-f7bc9b209e27c0b617378400136cc663a6314d0c.tar.xz
cpufreq: stats: Handle the case when trans_table goes beyond PAGE_SIZE
On platforms with large number of Pstates, the transition table, which is a NxN matrix, can overflow beyond the PAGE_SIZE boundary. This can be seen on POWER9 which has 100+ Pstates. As a result, each time the trans_table is read for any of the CPUs, we will get the following error. --------------------------------------------------- fill_read_buffer: show+0x0/0xa0 returned bad count --------------------------------------------------- This patch ensures that in case of an overflow, we print a warning once in the dmesg and return FILE TOO LARGE error for this and all subsequent accesses of trans_table. Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> 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_stats.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index e75880eb037d..1e55b5790853 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -118,8 +118,11 @@ static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "\n");
}
- if (len >= PAGE_SIZE)
- return PAGE_SIZE;
+
+ if (len >= PAGE_SIZE) {
+ pr_warn_once("cpufreq transition table exceeds PAGE_SIZE. Disabling\n");
+ return -EFBIG;
+ }
return len;
}
cpufreq_freq_attr_ro(trans_table);