drm/msm: fix potential deadlock in gpu init

Somewhere along the way, the firmware loader sprouted another lock
dependency, resulting in possible deadlock scenario:

 &dev->struct_mutex --> &sb->s_type->i_mutex_key#2 --> &mm->mmap_sem

which is problematic vs things like gem mmap.

So introduce a separate mutex to synchronize gpu init.

Signed-off-by: Rob Clark <robdclark@gmail.com>

3 files changed, 16 insertions, 8 deletions

diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index 76c1df73e747..655ce5b14ad0 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -95,7 +95,7 @@ int adreno_hw_init(struct msm_gpu *gpu)
 
         DBG("%s", gpu->name);
 
-        ret = msm_gem_get_iova_locked(gpu->rb->bo, gpu->id, &gpu->rb_iova);
+        ret = msm_gem_get_iova(gpu->rb->bo, gpu->id, &gpu->rb_iova);
         if (ret) {
                 gpu->rb_iova = 0;
                 dev_err(gpu->dev->dev, "could not map ringbuffer: %d\n", ret);
@@ -370,8 +370,10 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
                         return ret;
         }
 
+        mutex_lock(&drm->struct_mutex);
         gpu->memptrs_bo = msm_gem_new(drm, sizeof(*gpu->memptrs),
                         MSM_BO_UNCACHED);
+        mutex_unlock(&drm->struct_mutex);
         if (IS_ERR(gpu->memptrs_bo)) {
                 ret = PTR_ERR(gpu->memptrs_bo);
                 gpu->memptrs_bo = NULL;
@@ -379,13 +381,13 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
                 return ret;
         }
 
-        gpu->memptrs = msm_gem_vaddr_locked(gpu->memptrs_bo);
+        gpu->memptrs = msm_gem_vaddr(gpu->memptrs_bo);
         if (!gpu->memptrs) {
                 dev_err(drm->dev, "could not vmap memptrs\n");
                 return -ENOMEM;
         }
 
-        ret = msm_gem_get_iova_locked(gpu->memptrs_bo, gpu->base.id,
+        ret = msm_gem_get_iova(gpu->memptrs_bo, gpu->base.id,
                         &gpu->memptrs_iova);
         if (ret) {
                 dev_err(drm->dev, "could not map memptrs: %d\n", ret);
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index a2f5bf6da6f3..b447c01ad89c 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -181,7 +181,6 @@ static int msm_load(struct drm_device *dev, unsigned long flags)
         struct msm_kms *kms;
         int ret;
 
-
         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
         if (!priv) {
                 dev_err(dev->dev, "failed to allocate private data\n");
@@ -314,13 +313,15 @@ fail:
 
 static void load_gpu(struct drm_device *dev)
 {
+        static DEFINE_MUTEX(init_lock);
         struct msm_drm_private *priv = dev->dev_private;
         struct msm_gpu *gpu;
 
+        mutex_lock(&init_lock);
+
         if (priv->gpu)
-                return;
+                goto out;
 
-        mutex_lock(&dev->struct_mutex);
         gpu = a3xx_gpu_init(dev);
         if (IS_ERR(gpu)) {
                 dev_warn(dev->dev, "failed to load a3xx gpu\n");
@@ -330,7 +331,9 @@ static void load_gpu(struct drm_device *dev)
 
         if (gpu) {
                 int ret;
+                mutex_lock(&dev->struct_mutex);
                 gpu->funcs->pm_resume(gpu);
+                mutex_unlock(&dev->struct_mutex);
                 ret = gpu->funcs->hw_init(gpu);
                 if (ret) {
                         dev_err(dev->dev, "gpu hw init failed: %d\n", ret);
@@ -340,12 +343,12 @@ static void load_gpu(struct drm_device *dev)
                         /* give inactive pm a chance to kick in: */
                         msm_gpu_retire(gpu);
                 }
-
         }
 
         priv->gpu = gpu;
 
-        mutex_unlock(&dev->struct_mutex);
+out:
+        mutex_unlock(&init_lock);
 }
 
 static int msm_open(struct drm_device *dev, struct drm_file *file)
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 915240b4b80a..4a0dce587745 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -612,8 +612,11 @@ int msm_gpu_init(struct drm_device *drm, struct platform_device *pdev,
         }
         gpu->id = msm_register_mmu(drm, gpu->mmu);
 
+
         /* Create ringbuffer: */
+        mutex_lock(&drm->struct_mutex);
         gpu->rb = msm_ringbuffer_new(gpu, ringsz);
+        mutex_unlock(&drm->struct_mutex);
         if (IS_ERR(gpu->rb)) {
                 ret = PTR_ERR(gpu->rb);
                 gpu->rb = NULL;