Subject: Re: [Intel-gfx] [PATCH v3 11/11] drm/i915: replace Intel internal tracker with kernel core ref_tracker

From: "Das, Nirmoy" <[email-masked]>
Date: Fri, 6 Jan 2023 15:15:20 +0100

Hi Andrzej,

On 2/22/2022 12:25 AM, Andrzej Hajda wrote:
> 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 <[email-masked]>
> Reviewed-by: Chris Wilson <[email-masked]>
> ---
>   drivers/gpu/drm/i915/Kconfig.debug            |  11 +-
>   drivers/gpu/drm/i915/Makefile                 |   3 -
>   .../drm/i915/display/intel_display_power.c    |   2 +-
>   drivers/gpu/drm/i915/gt/intel_engine_pm.c     |   2 +-
>   drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   2 +-
>   drivers/gpu/drm/i915/intel_runtime_pm.c       |  25 +-
>   drivers/gpu/drm/i915/intel_runtime_pm.h       |   2 +-
>   drivers/gpu/drm/i915/intel_wakeref.c          |   8 +-
>   drivers/gpu/drm/i915/intel_wakeref.h          |  72 +++++-
>   drivers/gpu/drm/i915/intel_wakeref_tracker.c  | 234 ------------------
>   drivers/gpu/drm/i915/intel_wakeref_tracker.h  |  76 ------
>   11 files changed, 87 insertions(+), 350 deletions(-)
>   delete mode 100644 drivers/gpu/drm/i915/intel_wakeref_tracker.c
>   delete mode 100644 drivers/gpu/drm/i915/intel_wakeref_tracker.h
>
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> index 3bdc73f30a9e1..6c57f3e265f20 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -32,6 +32,7 @@ config DRM_I915_DEBUG
>   	select DEBUG_FS
>   	select PREEMPT_COUNT
>   	select I2C_CHARDEV
> +	select REF_TRACKER
>   	select STACKDEPOT
>   	select STACKTRACE
>   	select DRM_DP_AUX_CHARDEV
> @@ -46,7 +47,6 @@ config DRM_I915_DEBUG
>   	select DRM_I915_DEBUG_GEM
>   	select DRM_I915_DEBUG_GEM_ONCE
>   	select DRM_I915_DEBUG_MMIO
> -	select DRM_I915_TRACK_WAKEREF
>   	select DRM_I915_DEBUG_RUNTIME_PM
>   	select DRM_I915_DEBUG_WAKEREF
>   	select DRM_I915_SW_FENCE_DEBUG_OBJECTS
> @@ -238,18 +238,13 @@ config DRM_I915_DEBUG_VBLANK_EVADE
>   
>   	  If in doubt, say "N".
>   
> -config DRM_I915_TRACK_WAKEREF
> -	depends on STACKDEPOT
> -	depends on STACKTRACE
> -	bool
> -
>   config DRM_I915_DEBUG_RUNTIME_PM
>   	bool "Enable extra state checking for runtime PM"
>   	depends on DRM_I915
>   	default n
> +	select REF_TRACKER
>   	select STACKDEPOT
>   	select STACKTRACE
> -	select DRM_I915_TRACK_WAKEREF
>   	help
>   	  Choose this option to turn on extra state checking for the
>   	  runtime PM functionality. This may introduce overhead during
> @@ -263,9 +258,9 @@ config DRM_I915_DEBUG_WAKEREF
>   	bool "Enable extra tracking for wakerefs"
>   	depends on DRM_I915
>   	default n
> +	select REF_TRACKER
>   	select STACKDEPOT
>   	select STACKTRACE
> -	select DRM_I915_TRACK_WAKEREF
>   	help
>   	  Choose this option to turn on extra state checking and usage
>   	  tracking for the wakerefPM functionality. This may introduce
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 88a403d3294cb..1f8d71430e2e6 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -76,9 +76,6 @@ i915-$(CONFIG_DEBUG_FS) += \
>   	display/intel_display_debugfs.o \
>   	display/intel_pipe_crc.o
>   
> -i915-$(CONFIG_DRM_I915_TRACK_WAKEREF) += \
> -	intel_wakeref_tracker.o
> -
>   i915-$(CONFIG_PERF_EVENTS) += i915_pmu.o
>   
>   # "Graphics Technology" (aka we talk to the gpu)
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> index 9ebae7ac32356..0e1bf724f89b5 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> @@ -2107,7 +2107,7 @@ print_async_put_domains_state(struct i915_power_domains *power_domains)
>   						     struct drm_i915_private,
>   						     power_domains);
>   
> -	drm_dbg(&i915->drm, "async_put_wakeref %u\n",
> +	drm_dbg(&i915->drm, "async_put_wakeref %lu\n",
>   		power_domains->async_put_wakeref);
>   
>   	print_power_domains(power_domains, "async_put_domains[0]",
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> index 52e46e7830ff5..cf8cc348942cb 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> @@ -273,7 +273,7 @@ void intel_engine_init__pm(struct intel_engine_cs *engine)
>   {
>   	struct intel_runtime_pm *rpm = engine->uncore->rpm;
>   
> -	intel_wakeref_init(&engine->wakeref, rpm, &wf_ops);
> +	intel_wakeref_init(&engine->wakeref, rpm, &wf_ops, engine->name);
>   	intel_engine_init_heartbeat(engine);
>   }
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> index 7ee65a93f926f..01a055d0d0989 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> @@ -129,7 +129,7 @@ static const struct intel_wakeref_ops wf_ops = {
>   
>   void intel_gt_pm_init_early(struct intel_gt *gt)
>   {
> -	intel_wakeref_init(&gt->wakeref, gt->uncore->rpm, &wf_ops);
> +	intel_wakeref_init(&gt->wakeref, gt->uncore->rpm, &wf_ops, "GT");
>   	seqcount_mutex_init(&gt->stats.lock, &gt->wakeref.mutex);
>   }
>   
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 7bd10efa56bf3..18e4b2f169e75 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -54,35 +54,35 @@
>   
>   static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
>   {
> -	intel_wakeref_tracker_init(&rpm->debug);
> +	ref_tracker_dir_init(&rpm->debug, INTEL_REFTRACK_DEAD_COUNT, dev_name(rpm->kdev));
>   }
>   
>   static intel_wakeref_t
>   track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
>   {
> -	if (!rpm->available)
> +	if (!rpm->available || rpm->no_wakeref_tracking)
>   		return -1;
>   
> -	return intel_wakeref_tracker_add(&rpm->debug);
> +	return intel_ref_tracker_alloc(&rpm->debug);
>   }
>   
>   static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
>   					     intel_wakeref_t wakeref)
>   {
> -	intel_wakeref_tracker_remove(&rpm->debug, wakeref);
> +	if (!rpm->available || rpm->no_wakeref_tracking)
> +		return;
> +
> +	intel_ref_tracker_free(&rpm->debug, wakeref);
>   }
>   
>   static void untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
>   {
> -	struct drm_printer p = drm_debug_printer("i915");
> -
> -	intel_wakeref_tracker_reset(&rpm->debug, &p);
> +	ref_tracker_dir_exit(&rpm->debug);
>   }
>   
>   static noinline void
>   __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
>   {
> -	struct intel_wakeref_tracker saved;
>   	unsigned long flags;
>   
>   	if (!atomic_dec_and_lock_irqsave(&rpm->wakeref_count,
> @@ -90,15 +90,8 @@ __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
>   					 flags))
>   		return;
>   
> -	saved = __intel_wakeref_tracker_reset(&rpm->debug);
> +	__ref_tracker_dir_print(&rpm->debug, INTEL_REFTRACK_PRINT_LIMIT);
>   	spin_unlock_irqrestore(&rpm->debug.lock, flags);
> -
> -	if (saved.count) {
> -		struct drm_printer p = drm_debug_printer("i915");
> -
> -		__intel_wakeref_tracker_show(&saved, &p);
> -		intel_wakeref_tracker_fini(&saved);
> -	}
>   }
>   
>   void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.h b/drivers/gpu/drm/i915/intel_runtime_pm.h
> index 0871fa2176474..db5692f1eb67e 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.h
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.h
> @@ -61,7 +61,7 @@ struct intel_runtime_pm {
>   	 * paired rpm_put) we can remove corresponding pairs of and keep
>   	 * the array trimmed to active wakerefs.
>   	 */
> -	struct intel_wakeref_tracker debug;
> +	struct ref_tracker_dir debug;
>   #endif
>   };
>   
> diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
> index db4887e33ea60..97fe9a0f0adbd 100644
> --- a/drivers/gpu/drm/i915/intel_wakeref.c
> +++ b/drivers/gpu/drm/i915/intel_wakeref.c
> @@ -62,6 +62,9 @@ static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
>   	if (likely(!wf->ops->put(wf))) {
>   		rpm_put(wf);
>   		wake_up_var(&wf->wakeref);
> +#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
> +		ref_tracker_dir_exit(&wf->debug);
> +#endif

This seems is bit too early, we only need this at the end  as you have 
done with untrack_all_intel_runtime_pm_wakerefs()

otherwise the WARN_ON_ONE(dir->debug) from " ref_tracker: implement 
use-after-free detection" will

get triggered.

Regards,

Nirmoy

>   
>   	}
>   
>   unlock:
> @@ -96,7 +99,8 @@ static void __intel_wakeref_put_work(struct work_struct *wrk)
>   void __intel_wakeref_init(struct intel_wakeref *wf,
>   			  struct intel_runtime_pm *rpm,
>   			  const struct intel_wakeref_ops *ops,
> -			  struct intel_wakeref_lockclass *key)
> +			  struct intel_wakeref_lockclass *key,
> +			  const char *name)
>   {
>   	wf->rpm = rpm;
>   	wf->ops = ops;
> @@ -110,7 +114,7 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
>   			 "wakeref.work", &key->work, 0);
>   
>   #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
> -	intel_wakeref_tracker_init(&wf->debug);
> +	ref_tracker_dir_init(&wf->debug, INTEL_REFTRACK_DEAD_COUNT, name);
>   #endif
>   }
>   
> diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
> index 38439deefc5cc..e0cd78fb60761 100644
> --- a/drivers/gpu/drm/i915/intel_wakeref.h
> +++ b/drivers/gpu/drm/i915/intel_wakeref.h
> @@ -7,17 +7,24 @@
>   #ifndef INTEL_WAKEREF_H
>   #define INTEL_WAKEREF_H
>   
> +#include <drm/drm_print.h>
> +
>   #include <linux/atomic.h>
>   #include <linux/bitfield.h>
>   #include <linux/bits.h>
>   #include <linux/lockdep.h>
>   #include <linux/mutex.h>
>   #include <linux/refcount.h>
> +#include <linux/ref_tracker.h>
> +#include <linux/slab.h>
>   #include <linux/stackdepot.h>
>   #include <linux/timer.h>
>   #include <linux/workqueue.h>
>   
> -#include "intel_wakeref_tracker.h"
> +typedef unsigned long intel_wakeref_t;
> +
> +#define INTEL_REFTRACK_DEAD_COUNT 16
> +#define INTEL_REFTRACK_PRINT_LIMIT 16
>   
>   #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
>   #define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
> @@ -45,7 +52,7 @@ struct intel_wakeref {
>   	struct delayed_work work;
>   
>   #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
> -	struct intel_wakeref_tracker debug;
> +	struct ref_tracker_dir debug;
>   #endif
>   };
>   
> @@ -57,11 +64,12 @@ struct intel_wakeref_lockclass {
>   void __intel_wakeref_init(struct intel_wakeref *wf,
>   			  struct intel_runtime_pm *rpm,
>   			  const struct intel_wakeref_ops *ops,
> -			  struct intel_wakeref_lockclass *key);
> -#define intel_wakeref_init(wf, rpm, ops) do {				\
> +			  struct intel_wakeref_lockclass *key,
> +			  const char *name);
> +#define intel_wakeref_init(wf, rpm, ops, name) do {				\
>   	static struct intel_wakeref_lockclass __key;			\
>   									\
> -	__intel_wakeref_init((wf), (rpm), (ops), &__key);		\
> +	__intel_wakeref_init((wf), (rpm), (ops), &__key, name);		\
>   } while (0)
>   
>   int __intel_wakeref_get_first(struct intel_wakeref *wf);
> @@ -266,17 +274,67 @@ __intel_wakeref_defer_park(struct intel_wakeref *wf)
>    */
>   int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
>   
> +#define INTEL_WAKEREF_DEF ((intel_wakeref_t)(-1))
> +
> +static inline intel_wakeref_t intel_ref_tracker_alloc(struct ref_tracker_dir *dir)
> +{
> +	struct ref_tracker *user = NULL;
> +
> +	ref_tracker_alloc(dir, &user, GFP_NOWAIT);
> +
> +	return (intel_wakeref_t)user ?: INTEL_WAKEREF_DEF;
> +}
> +
> +static inline void intel_ref_tracker_free(struct ref_tracker_dir *dir,
> +					  intel_wakeref_t handle)
> +{
> +	struct ref_tracker *user;
> +
> +	user = (handle == INTEL_WAKEREF_DEF) ? NULL : (void *)handle;
> +
> +	ref_tracker_free(dir, &user);
> +}
> +
> +static inline void
> +intel_wakeref_tracker_show(struct ref_tracker_dir *dir,
> +			   struct drm_printer *p)
> +{
> +	const size_t buf_size = PAGE_SIZE;
> +	char *buf, *sb, *se;
> +	size_t count;
> +
> +	buf = kmalloc(buf_size, GFP_NOWAIT);
> +	if (!buf)
> +		return;
> +
> +	count = ref_tracker_dir_snprint(dir, buf, buf_size);
> +	if (!count)
> +		goto free;
> +	/* printk does not like big buffers, so we split it */
> +	for (sb = buf; *sb; sb = se + 1) {
> +		se = strchrnul(sb, '\n');
> +		drm_printf(p, "%.*s", (int)(se - sb + 1), sb);
> +		if (!*se)
> +			break;
> +	}
> +	if (count >= buf_size)
> +		drm_printf(p, "\n...dropped %zd extra bytes of leak report.\n",
> +			   count + 1 - buf_size);
> +free:
> +	kfree(buf);
> +}
> +
>   #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
>   
>   static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
>   {
> -	return intel_wakeref_tracker_add(&wf->debug);
> +	return intel_ref_tracker_alloc(&wf->debug);
>   }
>   
>   static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
>   					 intel_wakeref_t handle)
>   {
> -	intel_wakeref_tracker_remove(&wf->debug, handle);
> +	intel_ref_tracker_free(&wf->debug, handle);
>   }
>   
>   static inline void intel_wakeref_show(struct intel_wakeref *wf,
> diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.c b/drivers/gpu/drm/i915/intel_wakeref_tracker.c
> deleted file mode 100644
> index a0bcef13a1085..0000000000000
> --- a/drivers/gpu/drm/i915/intel_wakeref_tracker.c
> +++ /dev/null
> @@ -1,234 +0,0 @@
> -// SPDX-License-Identifier: MIT
> -/*
> - * Copyright © 2021 Intel Corporation
> - */
> -
> -#include <linux/slab.h>
> -#include <linux/stackdepot.h>
> -#include <linux/stacktrace.h>
> -#include <linux/sort.h>
> -
> -#include <drm/drm_print.h>
> -
> -#include "intel_wakeref.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 __print_depot_stack(depot_stack_handle_t stack,
> -				char *buf, int sz, int indent)
> -{
> -	unsigned long *entries;
> -	unsigned int nr_entries;
> -
> -	nr_entries = stack_depot_fetch(stack, &entries);
> -	stack_trace_snprint(buf, sz, entries, nr_entries, indent);
> -}
> -
> -static int cmphandle(const void *_a, const void *_b)
> -{
> -	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;
> -}
> -
> -void
> -__intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w,
> -			     struct drm_printer *p)
> -{
> -	unsigned long i;
> -	char *buf;
> -
> -	buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
> -	if (!buf)
> -		return;
> -
> -	if (w->last_acquire) {
> -		__print_depot_stack(w->last_acquire, buf, PAGE_SIZE, 2);
> -		drm_printf(p, "Wakeref last acquired:\n%s", buf);
> -	}
> -
> -	if (w->last_release) {
> -		__print_depot_stack(w->last_release, buf, PAGE_SIZE, 2);
> -		drm_printf(p, "Wakeref last released:\n%s", buf);
> -	}
> -
> -	drm_printf(p, "Wakeref count: %lu\n", w->count);
> -
> -	sort(w->owners, w->count, sizeof(*w->owners), cmphandle, NULL);
> -
> -	for (i = 0; i < w->count; i++) {
> -		depot_stack_handle_t stack = w->owners[i];
> -		unsigned long rep;
> -
> -		rep = 1;
> -		while (i + 1 < w->count && w->owners[i + 1] == stack)
> -			rep++, i++;
> -		__print_depot_stack(stack, buf, PAGE_SIZE, 2);
> -		drm_printf(p, "Wakeref x%lu taken at:\n%s", rep, buf);
> -	}
> -
> -	kfree(buf);
> -}
> -
> -void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w,
> -				struct drm_printer *p)
> -{
> -	struct intel_wakeref_tracker tmp = {};
> -
> -	do {
> -		unsigned long alloc = tmp.count;
> -		depot_stack_handle_t *s;
> -
> -		spin_lock_irq(&w->lock);
> -		tmp.count = w->count;
> -		if (tmp.count <= alloc)
> -			memcpy(tmp.owners, w->owners, tmp.count * sizeof(*s));
> -		tmp.last_acquire = w->last_acquire;
> -		tmp.last_release = w->last_release;
> -		spin_unlock_irq(&w->lock);
> -		if (tmp.count <= alloc)
> -			break;
> -
> -		s = krealloc(tmp.owners,
> -			     tmp.count * sizeof(*s),
> -			     GFP_NOWAIT | __GFP_NOWARN);
> -		if (!s)
> -			goto out;
> -
> -		tmp.owners = s;
> -	} while (1);
> -
> -	__intel_wakeref_tracker_show(&tmp, p);
> -
> -out:
> -	intel_wakeref_tracker_fini(&tmp);
> -}
> -
> -intel_wakeref_t intel_wakeref_tracker_add(struct intel_wakeref_tracker *w)
> -{
> -	depot_stack_handle_t stack, *stacks;
> -	unsigned long flags;
> -
> -	stack = __save_depot_stack();
> -	if (!stack)
> -		return -1;
> -
> -	spin_lock_irqsave(&w->lock, flags);
> -
> -	if (!w->count)
> -		w->last_acquire = stack;
> -
> -	stacks = krealloc(w->owners,
> -			  (w->count + 1) * sizeof(*stacks),
> -			  GFP_NOWAIT | __GFP_NOWARN);
> -	if (stacks) {
> -		stacks[w->count++] = stack;
> -		w->owners = stacks;
> -	} else {
> -		stack = -1;
> -	}
> -
> -	spin_unlock_irqrestore(&w->lock, flags);
> -
> -	return stack;
> -}
> -
> -void intel_wakeref_tracker_remove(struct intel_wakeref_tracker *w,
> -				  intel_wakeref_t stack)
> -{
> -	unsigned long flags, n;
> -	bool found = false;
> -
> -	if (unlikely(stack == -1))
> -		return;
> -
> -	spin_lock_irqsave(&w->lock, flags);
> -	for (n = w->count; n--; ) {
> -		if (w->owners[n] == stack) {
> -			memmove(w->owners + n,
> -				w->owners + n + 1,
> -				(--w->count - n) * sizeof(stack));
> -			found = true;
> -			break;
> -		}
> -	}
> -	spin_unlock_irqrestore(&w->lock, flags);
> -
> -	if (WARN(!found,
> -		 "Unmatched wakeref %x, tracking %lu\n",
> -		 stack, w->count)) {
> -		char *buf;
> -
> -		buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
> -		if (!buf)
> -			return;
> -
> -		__print_depot_stack(stack, buf, PAGE_SIZE, 2);
> -		pr_err("wakeref %x from\n%s", stack, buf);
> -
> -		stack = READ_ONCE(w->last_release);
> -		if (stack && !w->count) {
> -			__print_depot_stack(stack, buf, PAGE_SIZE, 2);
> -			pr_err("wakeref last released at\n%s", buf);
> -		}
> -
> -		kfree(buf);
> -	}
> -}
> -
> -struct intel_wakeref_tracker
> -__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w)
> -{
> -	struct intel_wakeref_tracker saved;
> -
> -	lockdep_assert_held(&w->lock);
> -
> -	saved = *w;
> -
> -	w->owners = NULL;
> -	w->count = 0;
> -	w->last_release = __save_depot_stack();
> -
> -	return saved;
> -}
> -
> -void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
> -				 struct drm_printer *p)
> -{
> -	struct intel_wakeref_tracker tmp;
> -
> -	spin_lock_irq(&w->lock);
> -	tmp = __intel_wakeref_tracker_reset(w);
> -	spin_unlock_irq(&w->lock);
> -
> -	if (tmp.count)
> -		__intel_wakeref_tracker_show(&tmp, p);
> -
> -	intel_wakeref_tracker_fini(&tmp);
> -}
> -
> -void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w)
> -{
> -	memset(w, 0, sizeof(*w));
> -	spin_lock_init(&w->lock);
> -	stack_depot_init();
> -}
> -
> -void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w)
> -{
> -	kfree(w->owners);
> -}
> diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.h b/drivers/gpu/drm/i915/intel_wakeref_tracker.h
> deleted file mode 100644
> index 61df68e28c0fb..0000000000000
> --- a/drivers/gpu/drm/i915/intel_wakeref_tracker.h
> +++ /dev/null
> @@ -1,76 +0,0 @@
> -/* SPDX-License-Identifier: MIT */
> -/*
> - * Copyright © 2019 Intel Corporation
> - */
> -
> -#ifndef INTEL_WAKEREF_TRACKER_H
> -#define INTEL_WAKEREF_TRACKER_H
> -
> -#include <linux/kconfig.h>
> -#include <linux/spinlock.h>
> -#include <linux/stackdepot.h>
> -
> -typedef depot_stack_handle_t intel_wakeref_t;
> -
> -struct drm_printer;
> -
> -struct intel_wakeref_tracker {
> -	spinlock_t lock;
> -
> -	depot_stack_handle_t last_acquire;
> -	depot_stack_handle_t last_release;
> -
> -	depot_stack_handle_t *owners;
> -	unsigned long count;
> -};
> -
> -#if IS_ENABLED(CONFIG_DRM_I915_TRACK_WAKEREF)
> -
> -void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w);
> -void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w);
> -
> -intel_wakeref_t intel_wakeref_tracker_add(struct intel_wakeref_tracker *w);
> -void intel_wakeref_tracker_remove(struct intel_wakeref_tracker *w,
> -			   intel_wakeref_t handle);
> -
> -struct intel_wakeref_tracker
> -__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w);
> -void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
> -				 struct drm_printer *p);
> -
> -void __intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w,
> -				  struct drm_printer *p);
> -void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w,
> -				struct drm_printer *p);
> -
> -#else
> -
> -static inline void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w) {}
> -static inline void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w) {}
> -
> -static inline intel_wakeref_t
> -intel_wakeref_tracker_add(struct intel_wakeref_tracker *w)
> -{
> -	return -1;
> -}
> -
> -static inline void
> -intel_wakeref_untrack_remove(struct intel_wakeref_tracker *w, intel_wakeref_t handle) {}
> -
> -static inline struct intel_wakeref_tracker
> -__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w)
> -{
> -	return (struct intel_wakeref_tracker){};
> -}
> -
> -static inline void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
> -					       struct drm_printer *p)
> -{
> -}
> -
> -static inline void __intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w, struct drm_printer *p) {}
> -static inline void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w, struct drm_printer *p) {}
> -
> -#endif
> -
> -#endif /* INTEL_WAKEREF_TRACKER_H */