[Intel-gfx] [PATCH v2 4/4] drm/i915: Fix locking in DRRS debugfs

[Ville Syrjala]

From: Ville Syrjälä <ville.syrj...@linux.intel.com>

Grab the crtc mutex so that looking at the crtc state is
actually safe.

Reviewed-by: Jani Nikula <jani.nik...@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_drrs.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_drrs.c 
b/drivers/gpu/drm/i915/display/intel_drrs.c
index a5d6682475d1..2b94a62ef65a 100644
--- a/drivers/gpu/drm/i915/display/intel_drrs.c
+++ b/drivers/gpu/drm/i915/display/intel_drrs.c
@@ -301,8 +301,14 @@ void intel_crtc_drrs_init(struct intel_crtc *crtc)
 static int intel_drrs_debugfs_status_show(struct seq_file *m, void *unused)
 {
        struct intel_crtc *crtc = m->private;
-       const struct intel_crtc_state *crtc_state =
-               to_intel_crtc_state(crtc->base.state);
+       const struct intel_crtc_state *crtc_state;
+       int ret;
+
+       ret = drm_modeset_lock_single_interruptible(&crtc->base.mutex);
+       if (ret)
+               return ret;
+
+       crtc_state = to_intel_crtc_state(crtc->base.state);
 
        mutex_lock(&crtc->drrs.mutex);
 
@@ -321,6 +327,8 @@ static int intel_drrs_debugfs_status_show(struct seq_file 
*m, void *unused)
 
        mutex_unlock(&crtc->drrs.mutex);
 
+       drm_modeset_unlock(&crtc->base.mutex);
+
        return 0;
 }
 
-- 
2.35.1