[PATCH 6/9] drm/i915: Separate wakeref tracking

Andrzej Hajda
2022-02-17T14:07:25Z

From: Chris Wilson <chris.p.wilson@intel.com>

Extract the callstack tracking of intel_runtime_pm.c into its own
utility so that that we can reuse it for other online debugging of
scoped wakerefs.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
drivers/gpu/drm/i915/Kconfig.debug | 9 +
drivers/gpu/drm/i915/Makefile | 4 +
drivers/gpu/drm/i915/intel_runtime_pm.c | 244 +++----------------
drivers/gpu/drm/i915/intel_runtime_pm.h | 10 +-
drivers/gpu/drm/i915/intel_wakeref.h | 6 +-
drivers/gpu/drm/i915/intel_wakeref_tracker.c | 234 ++++++++++++++++++
drivers/gpu/drm/i915/intel_wakeref_tracker.h | 76 ++++++
7 files changed, 355 insertions(+), 228 deletions(-)
create mode 100644 drivers/gpu/drm/i915/intel_wakeref_tracker.c
create 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 e7fd3e76f8a20..8b1973146e848 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -33,6 +33,7 @@ config DRM_I915_DEBUG
select PREEMPT_COUNT
select I2C_CHARDEV
select STACKDEPOT
+ select STACKTRACE
select DRM_DP_AUX_CHARDEV
select X86_MSR # used by igt/pm_rpm
select DRM_VGEM # used by igt/prime_vgem (dmabuf interop checks)
@@ -45,6 +46,7 @@ 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_SW_FENCE_DEBUG_OBJECTS
select DRM_I915_SELFTEST
@@ -235,11 +237,18 @@ 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 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
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 9d588d936e3dc..88a403d3294cb 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -75,6 +75,10 @@ i915-$(CONFIG_DEBUG_FS) += \
i915_debugfs_params.o \
display/intel_display_debugfs.o \
display/intel_pipe_crc.o
+
+i915-$(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/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 6ed5786bcd299..7bd10efa56bf3 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();
+ intel_wakeref_tracker_init(&rpm->debug);
}

-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)
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_wakeref_tracker_add(&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))
- 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_wakeref_tracker_remove(&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;
+ struct drm_printer p = drm_debug_printer("i915");

- 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);
+ intel_wakeref_tracker_reset(&rpm->debug, &p);
}

static noinline void
__intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
{
- struct intel_runtime_pm_debug dbg = {};
+ struct intel_wakeref_tracker saved;
unsigned long flags;

if (!atomic_dec_and_lock_irqsave(&rpm->wakeref_count,
@@ -235,60 +90,21 @@ __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
flags))
return;

- __untrack_all_wakerefs(&rpm->debug, &dbg);
+ saved = __intel_wakeref_tracker_reset(&rpm->debug);
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);
+ if (saved.count) {
+ struct drm_printer p = drm_debug_printer("i915");

- dump_and_free_wakeref_tracking(&dbg);
+ __intel_wakeref_tracker_show(&saved, &p);
+ intel_wakeref_tracker_fini(&saved);
+ }
}

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_wakeref_tracker_show(&rpm->debug, p);
}

#else
@@ -297,14 +113,14 @@ 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)
{
}

@@ -349,9 +165,8 @@ intel_runtime_pm_release(struct intel_runtime_pm *rpm, int wakelock)
static intel_wakeref_t __intel_runtime_pm_get(struct intel_runtime_pm *rpm,
bool wakelock)
{
- struct drm_i915_private *i915 = container_of(rpm,
- struct drm_i915_private,
- runtime_pm);
+ struct drm_i915_private *i915 =
+ container_of(rpm, struct drm_i915_private, runtime_pm);
int ret;

ret = pm_runtime_get_sync(rpm->kdev);
@@ -556,9 +371,8 @@ void intel_runtime_pm_put(struct intel_runtime_pm *rpm, intel_wakeref_t wref)
*/
void intel_runtime_pm_enable(struct intel_runtime_pm *rpm)
{
- struct drm_i915_private *i915 = container_of(rpm,
- struct drm_i915_private,
- runtime_pm);
+ struct drm_i915_private *i915 =
+ container_of(rpm, struct drm_i915_private, runtime_pm);
struct device *kdev = rpm->kdev;

/*
@@ -604,9 +418,8 @@ void intel_runtime_pm_enable(struct intel_runtime_pm *rpm)

void intel_runtime_pm_disable(struct intel_runtime_pm *rpm)
{
- struct drm_i915_private *i915 = container_of(rpm,
- struct drm_i915_private,
- runtime_pm);
+ struct drm_i915_private *i915 =
+ container_of(rpm, struct drm_i915_private, runtime_pm);
struct device *kdev = rpm->kdev;

/* Transfer rpm ownership back to core */
@@ -621,9 +434,8 @@ void intel_runtime_pm_disable(struct intel_runtime_pm *rpm)

void intel_runtime_pm_driver_release(struct intel_runtime_pm *rpm)
{
- struct drm_i915_private *i915 = container_of(rpm,
- struct drm_i915_private,
- runtime_pm);
+ struct drm_i915_private *i915 =
+ container_of(rpm, struct drm_i915_private, runtime_pm);
int count = atomic_read(&rpm->wakeref_count);

drm_WARN(&i915->drm, count,
@@ -637,7 +449,7 @@ void intel_runtime_pm_driver_release(struct intel_runtime_pm *rpm)
void intel_runtime_pm_init_early(struct intel_runtime_pm *rpm)
{
struct drm_i915_private *i915 =
- container_of(rpm, struct drm_i915_private, runtime_pm);
+ container_of(rpm, struct drm_i915_private, runtime_pm);
struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
struct device *kdev = &pdev->dev;

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.h b/drivers/gpu/drm/i915/intel_runtime_pm.h
index d9160e3ff4afc..0871fa2176474 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.h
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.h
@@ -61,15 +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_runtime_pm_debug {
- spinlock_t lock;
-
- depot_stack_handle_t last_acquire;
- depot_stack_handle_t last_release;
-
- depot_stack_handle_t *owners;
- unsigned long count;
- } debug;
+ struct intel_wakeref_tracker debug;
#endif
};

diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index 4f4c2e15e736e..e6ba389652d74 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -17,7 +17,9 @@
#include <linux/timer.h>
#include <linux/workqueue.h>

-#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
+#include "intel_wakeref_tracker.h"
+
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
#define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
#else
#define INTEL_WAKEREF_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
@@ -26,8 +28,6 @@
struct intel_runtime_pm;
struct intel_wakeref;

-typedef depot_stack_handle_t intel_wakeref_t;
-
struct intel_wakeref_ops {
int (*get)(struct intel_wakeref *wf);
int (*put)(struct intel_wakeref *wf);
diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.c b/drivers/gpu/drm/i915/intel_wakeref_tracker.c
new file mode 100644
index 0000000000000..a0bcef13a1085
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref_tracker.c
@@ -0,0 +1,234 @@
+// 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
new file mode 100644
index 0000000000000..61df68e28c0fb
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref_tracker.h
@@ -0,0 +1,76 @@
+/* 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 */
--
2.25.1