Since commit 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage"),
__perf_event_overflow() stops the event with pmu->stop() and disables
it when the PERF_EVENT_IOC_REFRESH limit is reached. When userspace
re-arms the event with PERF_EVENT_IOC_REFRESH, the event is enabled
again and pmu->add() is called with PERF_EF_START.
hw_breakpoint_add() sets PERF_HES_STOPPED when PERF_EF_START is
missing, but never clears it. The flag set by pmu->stop() stays, and
perf_bp_event() drops every later hit, so a breakpoint re-armed this
way delivers only its first overflow.
Set the state from PERF_EF_START on every add, as perf_swevent_add()
does.
Fixes: 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage")
Assisted-by: LLM
Signed-off-by: Paolo Bertinetti <[email protected]>
Cc: [email protected]
---
kernel/events/hw_breakpoint.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 789add0c185a..7a606213f33d 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -968,8 +968,7 @@ static int hw_breakpoint_event_init(struct perf_event *bp)
static int hw_breakpoint_add(struct perf_event *bp, int flags)
{
- if (!(flags & PERF_EF_START))
- bp->hw.state = PERF_HES_STOPPED;
+ bp->hw.state = (flags & PERF_EF_START) ? 0 : PERF_HES_STOPPED;
if (is_sampling_event(bp)) {
bp->hw.last_period = bp->hw.sample_period;
--
2.53.0
