drm/i915: Markup paired operations on wakerefs

The majority of runtime-pm operations are bounded and scoped within a
function; these are easy to verify that the wakeref are handled
correctly. We can employ the compiler to help us, and reduce the number
of wakerefs tracked when debugging, by passing around cookies provided
by the various rpm_get functions to their rpm_put counterpart. This
makes the pairing explicit, and given the required wakeref cookie the
compiler can verify that we pass an initialised value to the rpm_put
(quite handy for double checking error paths).

For regular builds, the compiler should be able to eliminate the unused
local variables and the program growth should be minimal. Fwiw, it came
out as a net improvement as gcc was able to refactor rpm_get and
rpm_get_if_in_use together,

v2: Just s/rpm_put/rpm_put_unchecked/ everywhere, leaving the manual
mark up for smaller more targeted patches.
v3: Mention the cookie in Returns

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>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-2-chris@chris-wilson.co.uk

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c
index d3ebdbc0182e..1b1581a42aa1 100644
--- a/drivers/gpu/drm/i915/intel_guc_log.c
+++ b/drivers/gpu/drm/i915/intel_guc_log.c
@@ -445,7 +445,7 @@ static void guc_log_capture_logs(struct intel_guc_log *log)
 	 */
 	intel_runtime_pm_get(dev_priv);
 	guc_action_flush_log_complete(guc);
-	intel_runtime_pm_put(dev_priv);
+	intel_runtime_pm_put_unchecked(dev_priv);
 }
 
 int intel_guc_log_create(struct intel_guc_log *log)
@@ -528,7 +528,7 @@ int intel_guc_log_set_level(struct intel_guc_log *log, u32 level)
 	ret = guc_action_control_log(guc, GUC_LOG_LEVEL_IS_VERBOSE(level),
 				     GUC_LOG_LEVEL_IS_ENABLED(level),
 				     GUC_LOG_LEVEL_TO_VERBOSITY(level));
-	intel_runtime_pm_put(dev_priv);
+	intel_runtime_pm_put_unchecked(dev_priv);
 	if (ret) {
 		DRM_DEBUG_DRIVER("guc_log_control action failed %d\n", ret);
 		goto out_unlock;
@@ -610,7 +610,7 @@ void intel_guc_log_relay_flush(struct intel_guc_log *log)
 
 	intel_runtime_pm_get(i915);
 	guc_action_flush_log(guc);
-	intel_runtime_pm_put(i915);
+	intel_runtime_pm_put_unchecked(i915);
 
 	/* GuC would have updated log buffer by now, so capture it */
 	guc_log_capture_logs(log);