linux-kernel - [PATCH 1/2] drm/amdgpu: Move racy global PMU list into device

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Message-Id: <20221028224813.1466450-1-briannorris@chromium.org>
Date:   Fri, 28 Oct 2022 15:48:12 -0700
From:   Brian Norris <briannorris@...omium.org>
To:     Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        Xinhui <Xinhui.Pan@....com>
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        amd-gfx@...ts.freedesktop.org,
        Brian Norris <briannorris@...omium.org>
Subject: [PATCH 1/2] drm/amdgpu: Move racy global PMU list into device

If there are multiple amdgpu devices, this list processing can be racy.

We're really treating this like a per-device list, so make that explicit
and remove the global list.

Signed-off-by: Brian Norris <briannorris@...omium.org>
---

 drivers/gpu/drm/amd/amdgpu/amdgpu.h     |  4 ++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c | 12 +++++-------
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 0e6ddf05c23c..e968b7f2417c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1063,6 +1063,10 @@ struct amdgpu_device {
 	struct work_struct		reset_work;
 
 	bool                            job_hang;
+
+#if IS_ENABLED(CONFIG_PERF_EVENTS)
+	struct list_head pmu_list;
+#endif
 };
 
 static inline struct amdgpu_device *drm_to_adev(struct drm_device *ddev)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c
index 71ee361d0972..24f2055a2f23 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c
@@ -23,6 +23,7 @@
 
 #include <linux/perf_event.h>
 #include <linux/init.h>
+#include <linux/list.h>
 #include "amdgpu.h"
 #include "amdgpu_pmu.h"
 
@@ -72,9 +73,6 @@ static ssize_t amdgpu_pmu_event_show(struct device *dev,
 			amdgpu_pmu_attr->event_str, amdgpu_pmu_attr->type);
 }
 
-static LIST_HEAD(amdgpu_pmu_list);
-
-
 struct amdgpu_pmu_attr {
 	const char *name;
 	const char *config;
@@ -558,7 +556,7 @@ static int init_pmu_entry_by_type_and_add(struct amdgpu_pmu_entry *pmu_entry,
 		pr_info("Detected AMDGPU %d Perf Events.\n", total_num_events);
 
 
-	list_add_tail(&pmu_entry->entry, &amdgpu_pmu_list);
+	list_add_tail(&pmu_entry->entry, &pmu_entry->adev->pmu_list);
 
 	return 0;
 err_register:
@@ -579,9 +577,7 @@ void amdgpu_pmu_fini(struct amdgpu_device *adev)
 {
 	struct amdgpu_pmu_entry *pe, *temp;
 
-	list_for_each_entry_safe(pe, temp, &amdgpu_pmu_list, entry) {
-		if (pe->adev != adev)
-			continue;
+	list_for_each_entry_safe(pe, temp, &adev->pmu_list, entry) {
 		list_del(&pe->entry);
 		perf_pmu_unregister(&pe->pmu);
 		kfree(pe->pmu.attr_groups);
@@ -623,6 +619,8 @@ int amdgpu_pmu_init(struct amdgpu_device *adev)
 	int ret = 0;
 	struct amdgpu_pmu_entry *pmu_entry, *pmu_entry_df;
 
+	INIT_LIST_HEAD(&adev->pmu_list);
+
 	switch (adev->asic_type) {
 	case CHIP_VEGA20:
 		pmu_entry_df = create_pmu_entry(adev, AMDGPU_PMU_PERF_TYPE_DF,
-- 
2.38.1.273.g43a17bfeac-goog