LGTM. Thanks.
On 9/2/2026 5:19 AM, Vinay Belgaumkar wrote: > Sashiko recommended some additional checks to prevent null pointer > access. Check for revoked states inside perf_event_read_local(), as > the pmu event may have already been freed at this point. Add a null > check inside __perf_event_read_cpu() as well before accessing the pmu > ptr. > > Cc: Dapeng Mi <[email protected]> > Signed-off-by: Vinay Belgaumkar <[email protected]> > --- > kernel/events/core.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index f19d27ac411d..bb90034a2054 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -4788,14 +4788,19 @@ static inline const struct cpumask > *perf_scope_cpu_topology_cpumask(unsigned int > > static int __perf_event_read_cpu(struct perf_event *event, int event_cpu) > { > + struct pmu *pmu = READ_ONCE(event->pmu); > int local_cpu = smp_processor_id(); > u16 local_pkg, event_pkg; > > if ((unsigned)event_cpu >= nr_cpu_ids) > return event_cpu; > > + if (!pmu) > + return -ENODEV; > + > if (event->group_caps & PERF_EV_CAP_READ_SCOPE) { > - const struct cpumask *cpumask = > perf_scope_cpu_topology_cpumask(event->pmu->scope, event_cpu); > + const struct cpumask *cpumask = > perf_scope_cpu_topology_cpumask(pmu->scope, > + > event_cpu); > > if (cpumask && cpumask_test_cpu(local_cpu, cpumask)) > return local_cpu; > @@ -4917,6 +4922,11 @@ int perf_event_read_local(struct perf_event *event, > u64 *value, > goto out; > } > > + if (READ_ONCE(event->state) <= PERF_EVENT_STATE_REVOKED) { > + ret = -ENODEV; > + goto out; > + } > + > /* > * Get the event CPU numbers, and adjust them to local if the event is > * a per-package event that can be read locally
