From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20250117151913.3043942-2-kan.liang@xxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/lkml/20250115154949.3147-1-ravi.bangoria@xxxxxxx/
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
Patches currently in stable-queue which might be from kan.liang@xxxxxxxxxxxxxxx are
queue-5.4/perf-header-fix-one-memory-leakage-in-process_bpf_pr.patch
queue-5.4/perf-header-fix-one-memory-leakage-in-process_bpf_bt.patch
queue-5.4/perf-top-don-t-complain-about-lack-of-vmlinux-when-n.patch
queue-5.4/perf-report-fix-misleading-help-message-about-demang.patch
queue-5.4/perf-core-fix-low-freq-setting-via-ioc_period.patch
