drm/i915: Replace custom intel runtime_pm tracker with ref_tracker library

Beside reusing existing code, the main advantage of ref_tracker is
tracking per instance of wakeref. It allows also to catch double
put.
On the other side we lose information about the first acquire and
the last release, but the advantages outweigh it.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030-ref_tracker_i915-v1-1-006fe6b96421@intel.com

1 files changed, 17 insertions, 204 deletions

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 8743153fad87..91491111dbd5 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -52,182 +52,37 @@
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
 
-#include <linux/sort.h>
-
-#define STACKDEPTH 8
-
-static noinline depot_stack_handle_t __save_depot_stack(void)
-{
-	unsigned long entries[STACKDEPTH];
-	unsigned int n;
-
-	n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
-	return stack_depot_save(entries, n, GFP_NOWAIT | __GFP_NOWARN);
-}
-
 static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
-	spin_lock_init(&rpm->debug.lock);
-	stack_depot_init();
+	ref_tracker_dir_init(&rpm->debug, INTEL_REFTRACK_DEAD_COUNT, dev_name(rpm->kdev));
 }
 
-static noinline depot_stack_handle_t
+static intel_wakeref_t
 track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
-	depot_stack_handle_t stack, *stacks;
-	unsigned long flags;
-
-	if (rpm->no_wakeref_tracking)
-		return -1;
-
-	stack = __save_depot_stack();
-	if (!stack)
+	if (!rpm->available || rpm->no_wakeref_tracking)
 		return -1;
 
-	spin_lock_irqsave(&rpm->debug.lock, flags);
-
-	if (!rpm->debug.count)
-		rpm->debug.last_acquire = stack;
-
-	stacks = krealloc(rpm->debug.owners,
-			  (rpm->debug.count + 1) * sizeof(*stacks),
-			  GFP_NOWAIT | __GFP_NOWARN);
-	if (stacks) {
-		stacks[rpm->debug.count++] = stack;
-		rpm->debug.owners = stacks;
-	} else {
-		stack = -1;
-	}
-
-	spin_unlock_irqrestore(&rpm->debug.lock, flags);
-
-	return stack;
+	return intel_ref_tracker_alloc(&rpm->debug);
 }
 
 static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
-					     depot_stack_handle_t stack)
+					     intel_wakeref_t wakeref)
 {
-	struct drm_i915_private *i915 = container_of(rpm,
-						     struct drm_i915_private,
-						     runtime_pm);
-	unsigned long flags, n;
-	bool found = false;
-
-	if (unlikely(stack == -1))
+	if (!rpm->available || rpm->no_wakeref_tracking)
 		return;
 
-	spin_lock_irqsave(&rpm->debug.lock, flags);
-	for (n = rpm->debug.count; n--; ) {
-		if (rpm->debug.owners[n] == stack) {
-			memmove(rpm->debug.owners + n,
-				rpm->debug.owners + n + 1,
-				(--rpm->debug.count - n) * sizeof(stack));
-			found = true;
-			break;
-		}
-	}
-	spin_unlock_irqrestore(&rpm->debug.lock, flags);
-
-	if (drm_WARN(&i915->drm, !found,
-		     "Unmatched wakeref (tracking %lu), count %u\n",
-		     rpm->debug.count, atomic_read(&rpm->wakeref_count))) {
-		char *buf;
-
-		buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
-		if (!buf)
-			return;
-
-		stack_depot_snprint(stack, buf, PAGE_SIZE, 2);
-		DRM_DEBUG_DRIVER("wakeref %x from\n%s", stack, buf);
-
-		stack = READ_ONCE(rpm->debug.last_release);
-		if (stack) {
-			stack_depot_snprint(stack, buf, PAGE_SIZE, 2);
-			DRM_DEBUG_DRIVER("wakeref last released at\n%s", buf);
-		}
-
-		kfree(buf);
-	}
+	intel_ref_tracker_free(&rpm->debug, wakeref);
 }
 
-static int cmphandle(const void *_a, const void *_b)
+static void untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
 {
-	const depot_stack_handle_t * const a = _a, * const b = _b;
-
-	if (*a < *b)
-		return -1;
-	else if (*a > *b)
-		return 1;
-	else
-		return 0;
-}
-
-static void
-__print_intel_runtime_pm_wakeref(struct drm_printer *p,
-				 const struct intel_runtime_pm_debug *dbg)
-{
-	unsigned long i;
-	char *buf;
-
-	buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
-	if (!buf)
-		return;
-
-	if (dbg->last_acquire) {
-		stack_depot_snprint(dbg->last_acquire, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref last acquired:\n%s", buf);
-	}
-
-	if (dbg->last_release) {
-		stack_depot_snprint(dbg->last_release, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref last released:\n%s", buf);
-	}
-
-	drm_printf(p, "Wakeref count: %lu\n", dbg->count);
-
-	sort(dbg->owners, dbg->count, sizeof(*dbg->owners), cmphandle, NULL);
-
-	for (i = 0; i < dbg->count; i++) {
-		depot_stack_handle_t stack = dbg->owners[i];
-		unsigned long rep;
-
-		rep = 1;
-		while (i + 1 < dbg->count && dbg->owners[i + 1] == stack)
-			rep++, i++;
-		stack_depot_snprint(stack, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref x%lu taken at:\n%s", rep, buf);
-	}
-
-	kfree(buf);
-}
-
-static noinline void
-__untrack_all_wakerefs(struct intel_runtime_pm_debug *debug,
-		       struct intel_runtime_pm_debug *saved)
-{
-	*saved = *debug;
-
-	debug->owners = NULL;
-	debug->count = 0;
-	debug->last_release = __save_depot_stack();
-}
-
-static void
-dump_and_free_wakeref_tracking(struct intel_runtime_pm_debug *debug)
-{
-	if (debug->count) {
-		struct drm_printer p = drm_debug_printer("i915");
-
-		__print_intel_runtime_pm_wakeref(&p, debug);
-	}
-
-	kfree(debug->owners);
+	ref_tracker_dir_exit(&rpm->debug);
 }
 
 static noinline void
 __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 {
-	struct intel_runtime_pm_debug dbg = {};
 	unsigned long flags;
 
 	if (!atomic_dec_and_lock_irqsave(&rpm->wakeref_count,
@@ -235,60 +90,14 @@ __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 					 flags))
 		return;
 
-	__untrack_all_wakerefs(&rpm->debug, &dbg);
+	ref_tracker_dir_print_locked(&rpm->debug, INTEL_REFTRACK_PRINT_LIMIT);
 	spin_unlock_irqrestore(&rpm->debug.lock, flags);
-
-	dump_and_free_wakeref_tracking(&dbg);
-}
-
-static noinline void
-untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
-{
-	struct intel_runtime_pm_debug dbg = {};
-	unsigned long flags;
-
-	spin_lock_irqsave(&rpm->debug.lock, flags);
-	__untrack_all_wakerefs(&rpm->debug, &dbg);
-	spin_unlock_irqrestore(&rpm->debug.lock, flags);
-
-	dump_and_free_wakeref_tracking(&dbg);
 }
 
 void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
 				    struct drm_printer *p)
 {
-	struct intel_runtime_pm_debug dbg = {};
-
-	do {
-		unsigned long alloc = dbg.count;
-		depot_stack_handle_t *s;
-
-		spin_lock_irq(&rpm->debug.lock);
-		dbg.count = rpm->debug.count;
-		if (dbg.count <= alloc) {
-			memcpy(dbg.owners,
-			       rpm->debug.owners,
-			       dbg.count * sizeof(*s));
-		}
-		dbg.last_acquire = rpm->debug.last_acquire;
-		dbg.last_release = rpm->debug.last_release;
-		spin_unlock_irq(&rpm->debug.lock);
-		if (dbg.count <= alloc)
-			break;
-
-		s = krealloc(dbg.owners,
-			     dbg.count * sizeof(*s),
-			     GFP_NOWAIT | __GFP_NOWARN);
-		if (!s)
-			goto out;
-
-		dbg.owners = s;
-	} while (1);
-
-	__print_intel_runtime_pm_wakeref(p, &dbg);
-
-out:
-	kfree(dbg.owners);
+	intel_ref_tracker_show(&rpm->debug, p);
 }
 
 #else
@@ -297,14 +106,14 @@ static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
 }
 
-static depot_stack_handle_t
+static intel_wakeref_t
 track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
 	return -1;
 }
 
 static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
-					     intel_wakeref_t wref)
+					     intel_wakeref_t wakeref)
 {
 }
 
@@ -639,7 +448,11 @@ void intel_runtime_pm_driver_release(struct intel_runtime_pm *rpm)
 		 "i915 raw-wakerefs=%d wakelocks=%d on cleanup\n",
 		 intel_rpm_raw_wakeref_count(count),
 		 intel_rpm_wakelock_count(count));
+}
 
+void intel_runtime_pm_driver_last_release(struct intel_runtime_pm *rpm)
+{
+	intel_runtime_pm_driver_release(rpm);
 	untrack_all_intel_runtime_pm_wakerefs(rpm);
 }