On Tue, Jun 19, 2018 at 11:15:39AM +0100, Suzuki K Poulose wrote:
> The armpmu uses get_event_idx callback to allocate an event
> counter for a given event, which marks the selected counter
> as "used". Now, when we delete the counter, the arm_pmu goes
> ahead and clears the "used" bit and then invokes the "clear_event_idx"
> call back, which kind of splits the job between the core code
> and the backend. Tidy this up by relying on the clear_event_idx
> to do the book keeping, if available. Otherwise, let the core
> driver do the default "clear" bit operation. This will be useful
> for adding the chained event support, where we leave the event
> idx maintenance to the backend.
>
> Also, when an event is removed from the PMU, reset the hw.idx
> to indicate that a counter is not allocated for this event,
> to help the backends do better checks. This will be also used
> for the chain counter support.
>
> Cc: Mark Rutland <[email protected]>
> Cc: Will Deacon <[email protected]>
> Reviewed-by: Julien Thierry <[email protected]>
> Signed-off-by: Suzuki K Poulose <[email protected]>
TBH, I think it might be better to make clear_event_idx() mandatory,
such that each backend provides both clear / set, next to each other in
the code.
It's a bit more code, but it would restore orthogonality to the API.
Mark.
> ---
> Changes since v2:
> - Reset the event counter after an event is removed.
> ---
> arch/arm/kernel/perf_event_v7.c | 2 ++
> drivers/perf/arm_pmu.c | 17 +++++++++++++----
> 2 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
> index fd7ce01..765d265 100644
> --- a/arch/arm/kernel/perf_event_v7.c
> +++ b/arch/arm/kernel/perf_event_v7.c
> @@ -1637,6 +1637,7 @@ static void krait_pmu_clear_event_idx(struct
> pmu_hw_events *cpuc,
> bool venum_event = EVENT_VENUM(hwc->config_base);
> bool krait_event = EVENT_CPU(hwc->config_base);
>
> + clear_bit(hwc->idx, cpuc->used_mask);
> if (venum_event || krait_event) {
> bit = krait_event_to_bit(event, region, group);
> clear_bit(bit, cpuc->used_mask);
> @@ -1966,6 +1967,7 @@ static void scorpion_pmu_clear_event_idx(struct
> pmu_hw_events *cpuc,
> bool venum_event = EVENT_VENUM(hwc->config_base);
> bool scorpion_event = EVENT_CPU(hwc->config_base);
>
> + clear_bit(hwc->idx, cpuc->used_mask);
> if (venum_event || scorpion_event) {
> bit = scorpion_event_to_bit(event, region, group);
> clear_bit(bit, cpuc->used_mask);
> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index e3766a8..6e10e8c 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -227,6 +227,16 @@ static void armpmu_start(struct perf_event *event, int
> flags)
> armpmu->enable(event);
> }
>
> +static void armpmu_clear_event_idx(struct arm_pmu *armpmu,
> + struct pmu_hw_events *hw_events,
> + struct perf_event *event)
> +{
> + if (armpmu->clear_event_idx)
> + armpmu->clear_event_idx(hw_events, event);
> + else
> + clear_bit(event->hw.idx, hw_events->used_mask);
> +}
> +
> static void
> armpmu_del(struct perf_event *event, int flags)
> {
> @@ -237,11 +247,10 @@ armpmu_del(struct perf_event *event, int flags)
>
> armpmu_stop(event, PERF_EF_UPDATE);
> hw_events->events[idx] = NULL;
> - clear_bit(idx, hw_events->used_mask);
> - if (armpmu->clear_event_idx)
> - armpmu->clear_event_idx(hw_events, event);
> -
> + armpmu_clear_event_idx(armpmu, hw_events, event);
> perf_event_update_userpage(event);
> + /* Clear the allocated counter */
> + hwc->idx = -1;
> }
>
> static int
> --
> 2.7.4
>
