drm/i915: Track all held rpm wakerefs

Everytime we take a wakeref, record the stack trace of where it was
taken; clearing the set if we ever drop back to no owners. For debugging
a rpm leak, we can look at all the current wakerefs and check if they
have a matching rpm_put.

v2: Use skip=0 for unwinding the stack as it appears our noinline
function doesn't appear on the stack (nor does save_stack_trace itself!)
v3: Allow rpm->debug_count to disappear between inspections and so
avoid calling krealloc(0) as that may return a ZERO_PTR not NULL! (Mika)
v4: Show who last acquire/released the runtime pm

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Tested-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-1-chris@chris-wilson.co.uk

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 95813e21ae02..050cf8abd426 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2702,6 +2702,12 @@ static int i915_runtime_pm_status(struct seq_file *m, void *unused)
 		   pci_power_name(pdev->current_state),
 		   pdev->current_state);
 
+	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)) {
+		struct drm_printer p = drm_seq_file_printer(m);
+
+		print_intel_runtime_pm_wakeref(dev_priv, &p);
+	}
+
 	return 0;
 }