On 11-Oct-22 4:59 PM, Peter Zijlstra wrote:
> On Sat, Oct 08, 2022 at 11:54:24AM +0530, Ravi Bangoria wrote:
>
>> +static void perf_event_swap_task_ctx_data(struct perf_event_context *prev_ctx,
>> + struct perf_event_context *next_ctx)
>> +{
>> + struct perf_event_pmu_context *prev_epc, *next_epc;
>> +
>> + if (!prev_ctx->nr_task_data)
>> + return;
>> +
>> + prev_epc = list_first_entry(&prev_ctx->pmu_ctx_list,
>> + struct perf_event_pmu_context,
>> + pmu_ctx_entry);
>> + next_epc = list_first_entry(&next_ctx->pmu_ctx_list,
>> + struct perf_event_pmu_context,
>> + pmu_ctx_entry);
>> +
>> + while (&prev_epc->pmu_ctx_entry != &prev_ctx->pmu_ctx_list &&
>> + &next_epc->pmu_ctx_entry != &next_ctx->pmu_ctx_list) {
>> +
>> + WARN_ON_ONCE(prev_epc->pmu != next_epc->pmu);
>> +
>> + /*
>> + * PMU specific parts of task perf context can require
>> + * additional synchronization. As an example of such
>> + * synchronization see implementation details of Intel
>> + * LBR call stack data profiling;
>> + */
>> + if (prev_epc->pmu->swap_task_ctx)
>> + prev_epc->pmu->swap_task_ctx(prev_epc, next_epc);
>> + else
>> + swap(prev_epc->task_ctx_data, next_epc->task_ctx_data);
>
> Did I forget to advance the iterators here?
Yeah. Seems so. I overlooked it too.
Thanks,
Ravi
