From: jsg <jsg@openbsd.org>
Date: Mon, 12 Aug 2024 23:36:45 +0000 (+0000)
Subject: drm/i915: Lift runtime-pm acquire callbacks out of intel_wakeref.mutex
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=37dd9a7604fa9d378ffe16260eadb0eecfa1f92d;p=openbsd

drm/i915: Lift runtime-pm acquire callbacks out of intel_wakeref.mutex

From Chris Wilson
4cd64e9d2c7206db05e7162d0258b455726b7ec5 in mainline linux
---

diff --git a/sys/dev/pci/drm/i915/intel_wakeref.c b/sys/dev/pci/drm/i915/intel_wakeref.c
index fabd41b3cf6..5c3f009afe5 100644
--- a/sys/dev/pci/drm/i915/intel_wakeref.c
+++ b/sys/dev/pci/drm/i915/intel_wakeref.c
@@ -10,21 +10,12 @@
 #include "intel_wakeref.h"
 #include "i915_drv.h"
 
-static void rpm_get(struct intel_wakeref *wf)
-{
-	wf->wakeref = intel_runtime_pm_get(&wf->i915->runtime_pm);
-}
-
-static void rpm_put(struct intel_wakeref *wf)
-{
-	intel_wakeref_t wakeref = fetch_and_zero(&wf->wakeref);
-
-	intel_runtime_pm_put(&wf->i915->runtime_pm, wakeref);
-	INTEL_WAKEREF_BUG_ON(!wakeref);
-}
-
 int __intel_wakeref_get_first(struct intel_wakeref *wf)
 {
+	intel_wakeref_t wakeref;
+	int ret = 0;
+
+	wakeref = intel_runtime_pm_get(&wf->i915->runtime_pm);
 	/*
 	 * Treat get/put as different subclasses, as we may need to run
 	 * the put callback from under the shrinker and do not want to
@@ -32,41 +23,52 @@ int __intel_wakeref_get_first(struct intel_wakeref *wf)
 	 * upon acquiring the wakeref.
 	 */
 	mutex_lock_nested(&wf->mutex, SINGLE_DEPTH_NESTING);
-	if (!atomic_read(&wf->count)) {
-		int err;
-
-		rpm_get(wf);
 
-		err = wf->ops->get(wf);
-		if (unlikely(err)) {
-			rpm_put(wf);
-			mutex_unlock(&wf->mutex);
-			return err;
+	if (!atomic_read(&wf->count)) {
+		INTEL_WAKEREF_BUG_ON(wf->wakeref);
+		wf->wakeref = wakeref;
+		wakeref = 0;
+
+		ret = wf->ops->get(wf);
+		if (ret) {
+			wakeref = xchg(&wf->wakeref, 0);
+			wake_up_var(&wf->wakeref);
+			goto unlock;
 		}
 
 		smp_mb__before_atomic(); /* release wf->count */
 	}
+
 	atomic_inc(&wf->count);
+	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
+
+unlock:
 	mutex_unlock(&wf->mutex);
+	if (unlikely(wakeref))
+		intel_runtime_pm_put(&wf->i915->runtime_pm, wakeref);
 
-	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
-	return 0;
+	return ret;
 }
 
 static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
 {
+	intel_wakeref_t wakeref = 0;
+
 	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
 	if (unlikely(!atomic_dec_and_test(&wf->count)))
 		goto unlock;
 
 	/* ops->put() must reschedule its own release on error/deferral */
 	if (likely(!wf->ops->put(wf))) {
-		rpm_put(wf);
+		INTEL_WAKEREF_BUG_ON(!wf->wakeref);
+		wakeref = xchg(&wf->wakeref, 0);
 		wake_up_var(&wf->wakeref);
 	}
 
 unlock:
 	mutex_unlock(&wf->mutex);
+	if (wakeref)
+		intel_runtime_pm_put(&wf->i915->runtime_pm, wakeref);
 }
 
 void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags)