[PATCH 36/37] drm,i915 - atomic mutex hacks

[Jason Wessel]

Here are some hacks to work around mutex crashes in the drm / i915
code.

For now, this is the only way to make the kms / kgdb path safe on an
SMP system.

CC: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
CC: David Airlie <airlied@xxxxxxxx>
Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_fb_helper.c      |   18 ++++++++++++++++++
 drivers/gpu/drm/i915/intel_display.c |   21 +++++++++++++++++++++
 2 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index b390fd8..ac9ca4a 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -400,8 +400,14 @@ static void drm_fb_helper_on(struct fb_info *info)
 			    !crtc->enabled)
 				continue;
 
+#ifdef CONFIG_KGDB
+			if (atomic_read(&kgdb_active) == -1)
+#endif
 			mutex_lock(&dev->mode_config.mutex);
 			crtc_funcs->dpms(crtc, DRM_MODE_DPMS_ON);
+#ifdef CONFIG_KGDB
+			if (atomic_read(&kgdb_active) == -1)
+#endif
 			mutex_unlock(&dev->mode_config.mutex);
 
 			/* Found a CRTC on this fb, now find encoders */
@@ -410,8 +416,14 @@ static void drm_fb_helper_on(struct fb_info *info)
 					struct drm_encoder_helper_funcs *encoder_funcs;
 
 					encoder_funcs = encoder->helper_private;
+#ifdef CONFIG_KGDB
+					if (atomic_read(&kgdb_active) == -1)
+#endif
 					mutex_lock(&dev->mode_config.mutex);
 					encoder_funcs->dpms(encoder, DRM_MODE_DPMS_ON);
+#ifdef CONFIG_KGDB
+					if (atomic_read(&kgdb_active) == -1)
+#endif
 					mutex_unlock(&dev->mode_config.mutex);
 				}
 			}
@@ -828,8 +840,14 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
 		modeset->y = var->yoffset;
 
 		if (modeset->num_connectors) {
+#ifdef CONFIG_KGDB
+			if (atomic_read(&kgdb_active) == -1)
+#endif
 			mutex_lock(&dev->mode_config.mutex);
 			ret = crtc->funcs->set_config(modeset);
+#ifdef CONFIG_KGDB
+			if (atomic_read(&kgdb_active) == -1)
+#endif
 			mutex_unlock(&dev->mode_config.mutex);
 			if (!ret) {
 				info->var.xoffset = var->xoffset;
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 71816db..669f9b4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -949,6 +949,12 @@ intel_find_pll_g4x_dp(const intel_limit_t *limit, struct drm_crtc *crtc,
 void
 intel_wait_for_vblank(struct drm_device *dev)
 {
+#ifdef CONFIG_KGDB
+	if (atomic_read(&kgdb_active) != -1) {
+		mdelay(20);
+		return;
+	}
+#endif /* CONFIG_KGDB */
 	/* Wait for 20ms, i.e. one cycle at 50hz. */
 	msleep(20);
 }
@@ -1371,9 +1377,15 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
 	obj = intel_fb->obj;
 	obj_priv = obj->driver_private;
 
+#ifdef CONFIG_KGDB
+	if (atomic_read(&kgdb_active) == -1)
+#endif
 	mutex_lock(&dev->struct_mutex);
 	ret = intel_pin_and_fence_fb_obj(dev, obj);
 	if (ret != 0) {
+#ifdef CONFIG_KGDB
+		if (atomic_read(&kgdb_active) == -1)
+#endif
 		mutex_unlock(&dev->struct_mutex);
 		return ret;
 	}
@@ -1381,6 +1393,9 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
 	ret = i915_gem_object_set_to_gtt_domain(obj, 1);
 	if (ret != 0) {
 		i915_gem_object_unpin(obj);
+#ifdef CONFIG_KGDB
+		if (atomic_read(&kgdb_active) == -1)
+#endif
 		mutex_unlock(&dev->struct_mutex);
 		return ret;
 	}
@@ -1408,6 +1423,9 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
 	default:
 		DRM_ERROR("Unknown color depth\n");
 		i915_gem_object_unpin(obj);
+#ifdef CONFIG_KGDB
+	if (atomic_read(&kgdb_active) == -1)
+#endif
 		mutex_unlock(&dev->struct_mutex);
 		return -EINVAL;
 	}
@@ -1452,6 +1470,9 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
 	}
 	intel_increase_pllclock(crtc, true);
 
+#ifdef CONFIG_KGDB
+	if (atomic_read(&kgdb_active) == -1)
+#endif
 	mutex_unlock(&dev->struct_mutex);
 
 	if (!dev->primary->master)
-- 
1.6.4.rc1

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