First part of intel_cmt_event_read. Error conditions and placeholder for oncoming chunks.
Signed-off-by: David Carrillo-Cisneros <[email protected]> --- arch/x86/events/intel/cmt.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/arch/x86/events/intel/cmt.c b/arch/x86/events/intel/cmt.c index ef1000f..f5ab48e 100644 --- a/arch/x86/events/intel/cmt.c +++ b/arch/x86/events/intel/cmt.c @@ -1320,6 +1320,31 @@ static struct monr *monr_next_descendant_post(struct monr *pos, static int intel_cmt_event_read(struct perf_event *event) { + struct monr *monr = monr_from_event(event); + + /* + * preemption disabled since called holding + * event's ctx->lock raw_spin_lock. + */ + WARN_ON_ONCE(!preempt_count()); + + /* terminated monrs are zombies and must not be read. */ + if (WARN_ON_ONCE(monr->flags & CMT_MONR_ZOMBIE)) + return -ENXIO; + + /* + * Only event parent can return a value, everyone else share its + * rmid and therefore doesn't track occupancy independently. + */ + if (event->parent) { + local64_set(&event->count, 0); + return 0; + } + + if (event->attach_state & PERF_ATTACH_TASK) { + /* To add support in next patches in series */ + return -ENOTSUPP; + } /* To add support in next patches in series */ return -ENOTSUPP; } -- 2.8.0.rc3.226.g39d4020
