drm/i915: Release connector iterator on a digital port conflict.

Hitting the failure path through check_digital_port_conflicts triggers:

================================================
WARNING: lock held when returning to user space!
4.16.0-rc1-CI-kasan_1+ #1 Tainted: G        W
------------------------------------------------
kms_3d/1439 is leaving the kernel with locks still held!
1 lock held by kms_3d/1439:
 #0:  (drm_connector_list_iter){.+.+}, at: [<000000003745d183>] intel_atomic_check+0x1d9d/0x3ff0 [i915]

Rearrange the code to have a single exit path through the unlock.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180215091425.42364-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index cafb727..3c479e3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10705,6 +10705,7 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
        struct drm_connector_list_iter conn_iter;
        unsigned int used_ports = 0;
        unsigned int used_mst_ports = 0;
+       bool ret = true;
 
        /*
         * Walk the connector list instead of the encoder
@@ -10739,7 +10740,7 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
 
                        /* the same port mustn't appear more than once */
                        if (used_ports & port_mask)
-                               return false;
+                               ret = false;
 
                        used_ports |= port_mask;
                        break;
@@ -10757,7 +10758,7 @@ static bool check_digital_port_conflicts(struct drm_atomic_state *state)
        if (used_ports & used_mst_ports)
                return false;
 
-       return true;
+       return ret;
 }
 
 static void