3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Knut Petersen <[email protected]>

commit 723478c8a471403c53cf144999701f6e0c4bbd11 upstream.

/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 <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Weng Meiling <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 kernel/events/core.c |    2 +-
 kernel/sysctl.c      |    1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -190,7 +190,7 @@ int perf_proc_update_handler(struct ctl_
                void __user *buffer, size_t *lenp,
                loff_t *ppos)
 {
-       int ret = proc_dointvec(table, write, buffer, lenp, ppos);
+       int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 
        if (ret || !write)
                return ret;
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1049,6 +1049,7 @@ static struct ctl_table kern_table[] = {
                .maxlen         = sizeof(sysctl_perf_event_sample_rate),
                .mode           = 0644,
                .proc_handler   = perf_proc_update_handler,
+               .extra1         = &one,
        },
        {
                .procname       = "perf_cpu_time_max_percent",


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