On Fri, 24 Feb 2023, Andrzej Hajda <andrzej.ha...@intel.com> wrote:
> From: Chris Wilson <chris.p.wil...@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 <ch...@chris-wilson.co.uk>
> Signed-off-by: Andrzej Hajda <andrzej.ha...@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(-)
>
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug
> b/drivers/gpu/drm/i915/Kconfig.debug
> index 93dfb7ed970547..5fde52107e3b44 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -25,6 +25,7 @@ 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)
> @@ -37,6 +38,7 @@ 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
> @@ -227,11 +229,18 @@ 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 b2f91a1f826858..42daff6d575a82 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -81,6 +81,10 @@ 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 129746713d072f..72887e2bb03c21 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;
>
> /*
> @@ -611,9 +425,8 @@ 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 */
> @@ -628,9 +441,8 @@ 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);
>
> intel_wakeref_auto_fini(&rpm->userfault_wakeref);
> @@ -646,7 +458,7 @@ 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);
Lots of unrelated changes above that should be separate patches.
> 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 e592e8d6499a1f..a8dc2baf79844f 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.h
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.h
> @@ -83,15 +83,7 @@ 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;
There's a lot going on in the patch all around. Adding the struct to a
separate file could maybe be an individual patch to simplify the actual
changes.
This doesn't include the file that defines struct intel_wakeref_tracker;
it's included via intel_wakeref.h. But only if
> #endif
> };
>
> diff --git a/drivers/gpu/drm/i915/intel_wakeref.h
> b/drivers/gpu/drm/i915/intel_wakeref.h
> index 71b8a63f6f104d..20720fbcc28d46 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 00000000000000..a0bcef13a1085a
> --- /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"
This should really include the corresponding .h
i.e. intel_wakeref_tracker.h too. Now it gets included via
intel_wakeref.h but I'm not sure why.
> +
> +#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 00000000000000..61df68e28c0fbf
> --- /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 */
--
Jani Nikula, Intel Open Source Graphics Center
