[PATCH v3 0/3] perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT

[Charlie Jenkins <charlie@rivosinc.com>]

Introduce a new perf ioctl key PERF_EVENT_IOC_INC_EVENT_LIMIT that
functions the same as PERF_EVENT_IOC_REFRESH, except it does not
immediately enable counters.

Also create a libperf API perf_evsel__refresh() to allow libperf users
access to this ioctl key.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
This series is going to cause an issue conflict with another series I
sent [1]. The final patch of this series changes perf_evsel__ioctl() to
accept a unsigned long instead of void *. My preference would be for the
following patch to be squashed onto "libperf: Add perf_evsel__refresh()
function" when applied:

From 66ab7b57c8b5a94c02c8d82204338b0ebca48bc5 Mon Sep 17 00:00:00 2001
From: Charlie Jenkins <charlie@rivosinc.com>
Date: Mon, 6 Jan 2025 20:00:28 -0800
Subject: [PATCH] libperf: Fixup perf_evsel__get_id

This patch should be squashed onto
"libperf: Add perf_evsel__refresh() function" or
"libperf: Add perf_evsel__id() function" when merging.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
 tools/lib/perf/evsel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index 1cd1680d28d7..8690588c0ba1 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -521,7 +521,7 @@ int perf_evsel__period(struct perf_evsel *evsel, u64 period)
 
 static int perf_evsel__get_id(struct perf_evsel *evsel, int cpu_map_idx, int thread, u64 *id)
 {
-	return perf_evsel__ioctl(evsel, PERF_EVENT_IOC_ID, id, cpu_map_idx, thread);
+	return perf_evsel__ioctl(evsel, PERF_EVENT_IOC_ID, (unsigned long)id, cpu_map_idx, thread);
 }
 
 int perf_evsel__id(struct perf_evsel *evsel, u64 *ids[])
-- 
2.34.1

[1] https://lore.kernel.org/lkml/20250106-perf_evsel_get_id-v3-1-44eca9194f1e@rivosinc.com/T/#u

Changes in v3:
- Use uint64_t instead of __u64 for consistency
- Link to v2: https://lore.kernel.org/r/20240807-perf_set_event_limit-v2-0-823b78d04c76@rivosinc.com

Changes in v2:
- Drop discussion about signal race condition
- Add new patch "libperf: Add perf_evsel__refresh() function"
- This newly added patch was pulled from a different series with
  modifications to fit the new ioctl key
-
https://lore.kernel.org/lkml/20240726-overflow_check_libperf-v2-0-7d154dcf6bea@rivosinc.com/
will be updated
- Link to v1: https://lore.kernel.org/r/20240724-perf_set_event_limit-v1-0-e680c93eca55@rivosinc.com

---
Charlie Jenkins (3):
      perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT
      perf: Document PERF_EVENT_IOC_INC_EVENT_LIMIT
      libperf: Add perf_evsel__refresh() function

 include/linux/perf_event.h               |  4 +--
 include/uapi/linux/perf_event.h          |  1 +
 kernel/events/core.c                     | 17 +++++++----
 tools/include/uapi/linux/perf_event.h    |  1 +
 tools/lib/perf/Documentation/libperf.txt |  2 ++
 tools/lib/perf/evsel.c                   | 49 ++++++++++++++++++++++++++------
 tools/lib/perf/include/perf/evsel.h      |  2 ++
 tools/lib/perf/libperf.map               |  2 ++
 tools/perf/design.txt                    |  5 ++++
 9 files changed, 67 insertions(+), 16 deletions(-)
---
base-commit: ed60738a9b7ede4a4ae797d90be7fde3e10a36c7
change-id: 20240724-perf_set_event_limit-079f1b996376
-- 
- Charlie