perf core: Fix perf_proc_update_handler() bug

[thirdparty/kernel/stable.git] / kernel / events / core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 17d5d41464c60b35629aa5777f262ab8cf557c0e..92939b5397df2de78166d35e9666f4655be8bfa4 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -436,18 +436,18 @@ int perf_proc_update_handler(struct ctl_table *table, int write,
                void __user *buffer, size_t *lenp,
                loff_t *ppos)
 {
-       int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-
-       if (ret || !write)
-               return ret;
-
+       int ret;
+       int perf_cpu = sysctl_perf_cpu_time_max_percent;
        /*
         * If throttling is disabled don't allow the write:
         */
-       if (sysctl_perf_cpu_time_max_percent == 100 ||
-           sysctl_perf_cpu_time_max_percent == 0)
+       if (write && (perf_cpu == 100 || perf_cpu == 0))
                return -EINVAL;
 
+       ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+       if (ret || !write)
+               return ret;
+
        max_samples_per_tick = DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
        perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
        update_perf_cpu_limits();