From f7bc9b209e27c0b617378400136cc663a6314d0c Mon Sep 17 00:00:00 2001 From: "Gautham R. Shenoy" Date: Tue, 7 Nov 2017 13:39:29 +0530 Subject: 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 Acked-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq_stats.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers/cpufreq/cpufreq_stats.c') 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); -- cgit v1.2.3-59-g8ed1b