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Message-ID: <365bc18a-b0f6-4d51-4943-bdd39b48315e@intel.com>
Date: Wed, 1 Mar 2023 22:42:46 +0100
From: Andrzej Hajda <andrzej.hajda@...el.com>
To: Jani Nikula <jani.nikula@...ux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>
Cc: intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Chris Wilson <chris.p.wilson@...el.com>,
Chris Wilson <chris@...is-wilson.co.uk>,
dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 1/3] drm/i915: Separate wakeref tracking
On 27.02.2023 12:50, Jani Nikula wrote:
> On Fri, 24 Feb 2023, Andrzej Hajda <andrzej.hajda@...el.com> wrote:
>> From: Chris Wilson <chris.p.wilson@...el.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@...is-wilson.co.uk>
>> Signed-off-by: Andrzej Hajda <andrzej.hajda@...el.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.
OK
>
>> 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.
Hmm, the patch abstracts out wakeref_tracker from rpm to separate
'library'. In this context the change above looks quite natural and
atomic for me.
>
> 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.
Apparently some leftover, will fix it.
Regards
Andrzej
>
>> +
>> +#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 */
>
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