5.4-stable review patch. If anyone has any objections, please let me know.
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From: Kan Liang kan.liang@linux.intel.com
commit 0d39844150546fa1415127c5fbae26db64070dd3 upstream.
A low attr::freq value cannot be set via IOC_PERIOD on some platforms.
The perf_event_check_period() introduced in:
81ec3f3c4c4d ("perf/x86: Add check_period PMU callback")
was intended to check the period, rather than the frequency. A low frequency may be mistakenly rejected by limit_period().
Fix it.
Fixes: 81ec3f3c4c4d ("perf/x86: Add check_period PMU callback") Signed-off-by: Kan Liang kan.liang@linux.intel.com Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Ravi Bangoria ravi.bangoria@amd.com Cc: Peter Zijlstra peterz@infradead.org Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250117151913.3043942-2-kan.liang@linux.intel.com Closes: https://lore.kernel.org/lkml/20250115154949.3147-1-ravi.bangoria@amd.com/ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/events/core.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)
--- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5217,14 +5217,15 @@ static int perf_event_period(struct perf if (!value) return -EINVAL;
- if (event->attr.freq && value > sysctl_perf_event_sample_rate) - return -EINVAL; - - if (perf_event_check_period(event, value)) - return -EINVAL; - - if (!event->attr.freq && (value & (1ULL << 63))) - return -EINVAL; + if (event->attr.freq) { + if (value > sysctl_perf_event_sample_rate) + return -EINVAL; + } else { + if (perf_event_check_period(event, value)) + return -EINVAL; + if (value & (1ULL << 63)) + return -EINVAL; + }
event_function_call(event, __perf_event_period, &value);