Re: [PATCH] perf/x86/amd/uncore: turn amd_uncore_ctx events into a flexible array

["Mi, Dapeng" <dapeng1.mi@linux.intel.com>]

On 9/16/2026 4:58 AM, Ian Rogers wrote:
> On Fri, May 22, 2026 at 6:19 PM Rosen Penev <rosenp@gmail.com> wrote:
>> The events pointer was kzalloc_node()'d immediately after the parent
>> struct allocation, with the count (pmu->num_counters) trivially
>> available beforehand.  Move events to the struct tail as a flexible
>> array member and fold the two allocations into a single kzalloc_node()
>> with struct_size(), dropping the separate kfree(ctx->events) in the
>> free path.
>>
>> Assisted-by: Claude:Opus-4.7
>> Signed-off-by: Rosen Penev <rosenp@gmail.com>
>> ---
>>  arch/x86/events/amd/uncore.c | 15 +++------------
>>  1 file changed, 3 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
>> index 05cff39968ec..0e265fc1fef8 100644
>> --- a/arch/x86/events/amd/uncore.c
>> +++ b/arch/x86/events/amd/uncore.c
>> @@ -39,11 +39,11 @@ static int pmu_version;
>>  struct amd_uncore_ctx {
>>         int refcnt;
>>         int cpu;
>> -       struct perf_event **events;
>>         unsigned long active_mask[BITS_TO_LONGS(NUM_COUNTERS_MAX)];
>>         int nr_active;
>>         struct hrtimer hrtimer;
>>         u64 hrtimer_duration;
>> +       struct perf_event *events[];
> As the number of counters is fixed and events doesn't grow, this makes
> sense to me. Dapeng, what do you think?
It looks good to me. But it seems there is no Sashikio review, so better
resend to trigger Sashiko review for double check. Thanks.


>
> Thanks,
> Ian
>
>>  };
>>
>>  struct amd_uncore_pmu {
>> @@ -488,10 +488,8 @@ static void amd_uncore_ctx_free(struct amd_uncore *uncore, unsigned int cpu)
>>                 if (cpu == ctx->cpu)
>>                         cpumask_clear_cpu(cpu, &pmu->active_mask);
>>
>> -               if (!--ctx->refcnt) {
>> -                       kfree(ctx->events);
>> +               if (!--ctx->refcnt)
>>                         kfree(ctx);
>> -               }
>>
>>                 *per_cpu_ptr(pmu->ctx, cpu) = NULL;
>>         }
>> @@ -536,18 +534,11 @@ static int amd_uncore_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
>>                 /* Allocate context if sibling does not exist */
>>                 if (!curr) {
>>                         node = cpu_to_node(cpu);
>> -                       curr = kzalloc_node(sizeof(*curr), GFP_KERNEL, node);
>> +                       curr = kzalloc_node(struct_size(curr, events, pmu->num_counters), GFP_KERNEL, node);
>>                         if (!curr)
>>                                 goto fail;
>>
>>                         curr->cpu = cpu;
>> -                       curr->events = kzalloc_node(sizeof(*curr->events) *
>> -                                                   pmu->num_counters,
>> -                                                   GFP_KERNEL, node);
>> -                       if (!curr->events) {
>> -                               kfree(curr);
>> -                               goto fail;
>> -                       }
>>
>>                         amd_uncore_init_hrtimer(curr);
>>                         curr->hrtimer_duration = (u64)update_interval * NSEC_PER_MSEC;
>> --
>> 2.54.0
>>