[PATCH] drm/i915/pmu: Handle PCI unbind

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

...

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_pmu.c | 45 +++++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_pmu.h |  4 +++
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 69c0fa20eba1..9561935f7ec9 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -510,8 +510,12 @@ static int i915_pmu_event_init(struct perf_event *event)
 {
 	struct drm_i915_private *i915 =
 		container_of(event->pmu, typeof(*i915), pmu.base);
+	struct i915_pmu *pmu = &i915->pmu;
 	int ret;
 
+	if (pmu->closed)
+		return -ENODEV;
+
 	if (event->attr.type != event->pmu->type)
 		return -ENOENT;
 
@@ -594,9 +598,16 @@ static u64 __i915_pmu_event_read(struct perf_event *event)
 
 static void i915_pmu_event_read(struct perf_event *event)
 {
+	struct drm_i915_private *i915 =
+		container_of(event->pmu, typeof(*i915), pmu.base);
 	struct hw_perf_event *hwc = &event->hw;
+	struct i915_pmu *pmu = &i915->pmu;
 	u64 prev, new;
 
+	if (pmu->closed) {
+		event->hw.state = PERF_HES_STOPPED;
+		return;
+	}
 again:
 	prev = local64_read(&hwc->prev_count);
 	new = __i915_pmu_event_read(event);
@@ -724,20 +735,40 @@ static void i915_pmu_disable(struct perf_event *event)
 
 static void i915_pmu_event_start(struct perf_event *event, int flags)
 {
+	struct drm_i915_private *i915 =
+		container_of(event->pmu, typeof(*i915), pmu.base);
+	struct i915_pmu *pmu = &i915->pmu;
+
+	if (pmu->closed)
+		return;
+
 	i915_pmu_enable(event);
 	event->hw.state = 0;
 }
 
 static void i915_pmu_event_stop(struct perf_event *event, int flags)
 {
+	struct drm_i915_private *i915 =
+		container_of(event->pmu, typeof(*i915), pmu.base);
+	struct i915_pmu *pmu = &i915->pmu;
+
 	if (flags & PERF_EF_UPDATE)
 		i915_pmu_event_read(event);
-	i915_pmu_disable(event);
+	if (!pmu->closed)
+		i915_pmu_disable(event);
 	event->hw.state = PERF_HES_STOPPED;
 }
 
 static int i915_pmu_event_add(struct perf_event *event, int flags)
 {
+	struct drm_i915_private *i915 =
+		container_of(event->pmu, typeof(*i915), pmu.base);
+	struct i915_pmu *pmu = &i915->pmu;
+
+	if (pmu->closed)
+		return -ENODEV;
+
+	drm_dev_get(&i915->drm);
 	if (flags & PERF_EF_START)
 		i915_pmu_event_start(event, flags);
 
@@ -746,7 +777,11 @@ static int i915_pmu_event_add(struct perf_event *event, int flags)
 
 static void i915_pmu_event_del(struct perf_event *event, int flags)
 {
+	struct drm_i915_private *i915 =
+		container_of(event->pmu, typeof(*i915), pmu.base);
+
 	i915_pmu_event_stop(event, PERF_EF_UPDATE);
+	drm_dev_put(&i915->drm);
 }
 
 static int i915_pmu_event_event_idx(struct perf_event *event)
@@ -1167,7 +1202,13 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
 	if (!pmu->base.event_init)
 		return;
 
-	drm_WARN_ON(&i915->drm, pmu->enable);
+	/*
+	 * "Disconnect" the PMU callbacks - since all are atomic synchronize_rcu
+	 * ensures all currently executing ones will have exited before we
+	 * proceed with unregistration.
+	 */
+	pmu->closed = true;
+	synchronize_rcu();
 
 	hrtimer_cancel(&pmu->timer);
 
diff --git a/drivers/gpu/drm/i915/i915_pmu.h b/drivers/gpu/drm/i915/i915_pmu.h
index 941f0c14037c..59a0d19afb67 100644
--- a/drivers/gpu/drm/i915/i915_pmu.h
+++ b/drivers/gpu/drm/i915/i915_pmu.h
@@ -49,6 +49,10 @@ struct i915_pmu {
 	 * @base: PMU base.
 	 */
 	struct pmu base;
+	/**
+	 * @closed: i915 is unregistering.
+	 */
+	bool closed;
 	/**
 	 * @name: Name as registered with perf core.
 	 */
-- 
2.25.1