[PATCH v2] perf record: Fix destructor invocation and event counting in fdarray__filter

[Ian Rogers]

Fix the API-level fdarray filtering logic in fdarray__filter() following
the integration of the system-wide recording teardown fix. Rather than
bypassing the evaluation loop entirely for nonfilterable file
descriptors (which accidentally skips calling registered entry
destructors for control pipes and wakeup FDs, while creating poll storms
and reference leaks for system-wide events that also have nonfilterable
set), separate the lifecycle and masking logic.

Reorder the filtering sequence so that registered entry destructors are
safely executed first for all file descriptors. Then, utilize the
fdarray_flag__non_perf_event flag to perfectly distinguish and bypass
destructive file descriptor zeroing (.fd = -1) and revents mask
clearing for background control pipes and timers. This allows system-wide
event file descriptors to be correctly destroyed, zeroed, and filtered out upon
receiving POLLHUP/POLLERR signals without triggering busy loops, while safely
preserving control pipe teardown signaling and destructors.

Fixes: fb4751e79c45 ("perf record: Fix teardown hang on system-wide multi-threaded sessions")
Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/lib/api/fd/array.c    | 6 +++---
 tools/perf/builtin-record.c | 4 +++-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/lib/api/fd/array.c b/tools/lib/api/fd/array.c
index 16a047f1906e..92d9a3fb652c 100644
--- a/tools/lib/api/fd/array.c
+++ b/tools/lib/api/fd/array.c
@@ -115,9 +115,6 @@ int fdarray__filter(struct fdarray *fda, short revents,
 		return 0;
 
 	for (fd = 0; fd < fda->nr; ++fd) {
-		if (fda->priv[fd].flags & fdarray_flag__nonfilterable)
-			continue;
-
 		if (!fda->entries[fd].events)
 			continue;
 
@@ -125,6 +122,9 @@ int fdarray__filter(struct fdarray *fda, short revents,
 			if (entry_destructor)
 				entry_destructor(fda, fd, arg);
 
+			if (fda->priv[fd].flags & fdarray_flag__non_perf_event)
+				continue;
+
 			/*
 			 * Set fd to -1 so poll() ignores this entry; otherwise
 			 * POLLHUP/POLLERR are still reported for events=0 fds
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f58d7e3c7879..c6644dab1cfb 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1242,7 +1242,9 @@ static int record__alloc_thread_data(struct record *rec, struct evlist *evlist)
 				goto out_free;
 			}
 			ret = fdarray__add(&thread_data[t].pollfd, thread_data[t].pipes.msg[0],
-					   POLLIN | POLLERR | POLLHUP, fdarray_flag__nonfilterable);
+					   POLLIN | POLLERR | POLLHUP,
+					   fdarray_flag__nonfilterable |
+					   fdarray_flag__non_perf_event);
 			if (ret < 0) {
 				pr_err("Failed to add descriptor to thread[%d] pollfd\n", t);
 				goto out_free;
-- 
2.55.0.141.g00534a21ce-goog