On Wed, Sep 25, 2013 at 02:07:35PM +0200, Knut Petersen wrote: > From: Knut Petersen <[email protected]> > Date: Wed, 25 Sep 2013 13:34:57 +0200 > Subject: [PATCH] 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 <[email protected]> > --- > kernel/events/core.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index dd236b6..350bb53 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -198,6 +198,9 @@ int perf_proc_update_handler(struct ctl_table *table, int > write, > if (ret || !write) > return ret; > > + if (sysctl_perf_event_sample_rate <= 0) > + sysctl_perf_event_sample_rate = 1; > + > 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();
The 'normal' way of doing that is changing the sysctl table entry to use proc_dointvec_minmax and set .extra = &one. See for example &sysctl_sched_cfs_bandwidth_slice in kernel/sysctl.c -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
