perf: Enforce 1 as lower limit for perf_event_max_sample_rate
/proc/sys/kernel/perf_event_max_sample_rate will accept negative values as well as 0. Negative values are unreasonable, and 0 causes a divide by zero exception in perf_proc_update_handler. This patch enforces a lower limit of 1. Signed-off-by: Knut Petersen <Knut_Petersen@t-online.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/5242DB0C.4070005@t-online.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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2 changed files with 2 additions and 1 deletions
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@ -193,7 +193,7 @@ int perf_proc_update_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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loff_t *ppos)
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{
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{
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int ret = proc_dointvec(table, write, buffer, lenp, ppos);
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int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
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if (ret || !write)
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if (ret || !write)
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return ret;
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return ret;
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@ -1049,6 +1049,7 @@ static struct ctl_table kern_table[] = {
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.maxlen = sizeof(sysctl_perf_event_sample_rate),
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.maxlen = sizeof(sysctl_perf_event_sample_rate),
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.mode = 0644,
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.mode = 0644,
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.proc_handler = perf_proc_update_handler,
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.proc_handler = perf_proc_update_handler,
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.extra1 = &one,
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},
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},
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{
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{
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.procname = "perf_cpu_time_max_percent",
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.procname = "perf_cpu_time_max_percent",
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