lib/stackdepot: allow optional init and stack_table allocation by kvm…

…alloc() - fixup3

Due to cd06ab2 ("drm/locking: add backtrace for locking contended
locks without backoff") landing recently to -next adding a new stack depot
user in drivers/gpu/drm/drm_modeset_lock.c we need to add an appropriate
call to stack_depot_init() there as well.

Link: https://lkml.kernel.org/r/2a692365-cfa1-64f2-34e0-8aa5674dce5e@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Marco Elver <elver@google.com>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Oliver Glitta <glittao@gmail.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

drivers/gpu/drm/drm_modeset_lock.c

@@ -107,6 +107,11 @@ static void __drm_stack_depot_print(depot_stack_handle_t stack_depot)
 
 	kfree(buf);
 }
+
+static void __drm_stack_depot_init(void)
+{
+	stack_depot_init();
+}
 #else /* CONFIG_DRM_DEBUG_MODESET_LOCK */
 static depot_stack_handle_t __drm_stack_depot_save(void)
 {
@@ -115,6 +120,9 @@ static depot_stack_handle_t __drm_stack_depot_save(void)
 static void __drm_stack_depot_print(depot_stack_handle_t stack_depot)
 {
 }
+static void __drm_stack_depot_init(void)
+{
+}
 #endif /* CONFIG_DRM_DEBUG_MODESET_LOCK */
 
 /**
@@ -359,6 +367,7 @@ void drm_modeset_lock_init(struct drm_modeset_lock *lock)
 {
 	ww_mutex_init(&lock->mutex, &crtc_ww_class);
 	INIT_LIST_HEAD(&lock->head);
+	__drm_stack_depot_init();
 }
 EXPORT_SYMBOL(drm_modeset_lock_init);