[PATCH 1/4] perf: nvidia_t410_cmem_latency: fix cpuhp state leak on init failure

[PATCH 1/4] perf: nvidia_t410_cmem_latency: fix cpuhp state leak on init failure

[Saurav Sachidanand]

If platform_driver_register() fails, the cpuhp multi-state registered
by cpuhp_setup_state_multi() is never cleaned up. Add
cpuhp_remove_multi_state() on the error path, mirroring the cleanup
in cmem_lat_pmu_exit().

Fixes: 429b7638b2df ("perf: add NVIDIA Tegra410 CPU Memory Latency PMU")
Signed-off-by: Saurav Sachidanand <sauravsc@amazon.com>
---
 drivers/perf/nvidia_t410_cmem_latency_pmu.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/nvidia_t410_cmem_latency_pmu.c b/drivers/perf/nvidia_t410_cmem_latency_pmu.c
index acb8f5571522c..e27bf31b2b366 100644
--- a/drivers/perf/nvidia_t410_cmem_latency_pmu.c
+++ b/drivers/perf/nvidia_t410_cmem_latency_pmu.c
@@ -719,7 +719,11 @@ static int __init cmem_lat_pmu_init(void)
 
 	cmem_lat_pmu_cpuhp_state = ret;
 
-	return platform_driver_register(&cmem_lat_pmu_driver);
+	ret = platform_driver_register(&cmem_lat_pmu_driver);
+	if (ret)
+		cpuhp_remove_multi_state(cmem_lat_pmu_cpuhp_state);
+
+	return ret;
 }
 
 static void __exit cmem_lat_pmu_exit(void)
-- 
2.47.3

[PATCH 2/4] perf: nvidia_t410_cmem_latency: handle PERF_EF_UPDATE in stop

[Saurav Sachidanand]

cmem_lat_pmu_stop() does not read the final counter value when called
with PERF_EF_UPDATE. When perf core calls pmu->del() -> pmu->stop()
with PERF_EF_UPDATE, the last counter delta is lost because the event
is marked stopped without reading hardware.

Add the standard PMU stop pattern: bail out if already stopped, call
the event update function when PERF_EF_UPDATE is requested, then mark
the event stopped.

Fixes: 429b7638b2df ("perf: add NVIDIA Tegra410 CPU Memory Latency PMU")
Signed-off-by: Saurav Sachidanand <sauravsc@amazon.com>
---
 drivers/perf/nvidia_t410_cmem_latency_pmu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/perf/nvidia_t410_cmem_latency_pmu.c b/drivers/perf/nvidia_t410_cmem_latency_pmu.c
index e27bf31b2b366..c7fa54c7a7c9e 100644
--- a/drivers/perf/nvidia_t410_cmem_latency_pmu.c
+++ b/drivers/perf/nvidia_t410_cmem_latency_pmu.c
@@ -303,6 +303,12 @@ static void cmem_lat_pmu_start(struct perf_event *event, int pmu_flags)
 
 static void cmem_lat_pmu_stop(struct perf_event *event, int pmu_flags)
 {
+	if (event->hw.state & PERF_HES_STOPPED)
+		return;
+
+	if (pmu_flags & PERF_EF_UPDATE)
+		cmem_lat_pmu_event_update(event);
+
 	event->hw.state |= PERF_HES_STOPPED;
 }
 
-- 
2.47.3

[PATCH 3/4] perf: nvidia_t410_c2c: fix cpuhp state leak on init failure

[Saurav Sachidanand]

If platform_driver_register() fails, the cpuhp multi-state registered
by cpuhp_setup_state_multi() is never cleaned up. Add
cpuhp_remove_multi_state() on the error path, mirroring the cleanup
in nv_c2c_pmu_exit().

Fixes: 2f89b7f78c50 ("perf: add NVIDIA Tegra410 C2C PMU")
Signed-off-by: Saurav Sachidanand <sauravsc@amazon.com>
---
 drivers/perf/nvidia_t410_c2c_pmu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/nvidia_t410_c2c_pmu.c b/drivers/perf/nvidia_t410_c2c_pmu.c
index 411987153ff3f..662fa1bc833a5 100644
--- a/drivers/perf/nvidia_t410_c2c_pmu.c
+++ b/drivers/perf/nvidia_t410_c2c_pmu.c
@@ -1034,7 +1034,12 @@ static int __init nv_c2c_pmu_init(void)
 		return ret;
 
 	nv_c2c_pmu_cpuhp_state = ret;
-	return platform_driver_register(&nv_c2c_pmu_driver);
+
+	ret = platform_driver_register(&nv_c2c_pmu_driver);
+	if (ret)
+		cpuhp_remove_multi_state(nv_c2c_pmu_cpuhp_state);
+
+	return ret;
 }
 
 static void __exit nv_c2c_pmu_exit(void)
-- 
2.47.3

[PATCH 4/4] perf: nvidia_t410_c2c: handle PERF_EF_UPDATE in stop

[Saurav Sachidanand]

nv_c2c_pmu_stop() does not read the final counter value when called
with PERF_EF_UPDATE. The last counter delta is lost when perf core
removes the event.

Add the standard PMU stop pattern: bail out if already stopped, call
nv_c2c_pmu_event_update() when PERF_EF_UPDATE is requested, then mark
the event stopped.

Fixes: 2f89b7f78c50 ("perf: add NVIDIA Tegra410 C2C PMU")
Signed-off-by: Saurav Sachidanand <sauravsc@amazon.com>
---
 drivers/perf/nvidia_t410_c2c_pmu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/perf/nvidia_t410_c2c_pmu.c b/drivers/perf/nvidia_t410_c2c_pmu.c
index 662fa1bc833a5..39d0e661e4c5c 100644
--- a/drivers/perf/nvidia_t410_c2c_pmu.c
+++ b/drivers/perf/nvidia_t410_c2c_pmu.c
@@ -394,6 +394,12 @@ static void nv_c2c_pmu_start(struct perf_event *event, int pmu_flags)
 
 static void nv_c2c_pmu_stop(struct perf_event *event, int pmu_flags)
 {
+	if (event->hw.state & PERF_HES_STOPPED)
+		return;
+
+	if (pmu_flags & PERF_EF_UPDATE)
+		nv_c2c_pmu_event_update(event);
+
 	event->hw.state |= PERF_HES_STOPPED;
 }
 
-- 
2.47.3