linux change

drm_global_mutext.patch

diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 036cd27..8c568c7 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -44,6 +44,7 @@
 
 /* from BKL pushdown */
 DEFINE_MUTEX(drm_global_mutex);
+EXPORT_SYMBOL(drm_global_mutex);
 
 /**
  * DOC: file operations
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 92bfe47..b966781 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -137,6 +137,7 @@
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
 #include "intel_mocs.h"
+#include "../drm_internal.h"
 
 #define GEN9_LR_CONTEXT_RENDER_SIZE (22 * PAGE_SIZE)
 #define GEN8_LR_CONTEXT_RENDER_SIZE (20 * PAGE_SIZE)
@@ -313,6 +314,7 @@ intel_lr_context_descriptor_update(struct i915_gem_context *ctx,
 
 	BUILD_BUG_ON(MAX_CONTEXT_HW_ID > (1<<GEN8_CTX_ID_WIDTH));
 
+	mutex_lock(&drm_global_mutex);
 	desc = ctx->desc_template;				/* bits  3-4  */
 	desc |= engine->ctx_desc_template;			/* bits  0-11 */
 	desc |= i915_ggtt_offset(ce->state) + LRC_PPHWSP_PN * PAGE_SIZE;
@@ -320,6 +322,7 @@ intel_lr_context_descriptor_update(struct i915_gem_context *ctx,
 	desc |= (u64)ctx->hw_id << GEN8_CTX_ID_SHIFT;		/* bits 32-52 */
 
 	ce->lrc_desc = desc;
+	mutex_unlock(&drm_global_mutex);
 }
 
 uint64_t intel_lr_context_descriptor(struct i915_gem_context *ctx,