drm/vmwgfx: Clean up fbdev modeset locking

At least since the atomic port, the vmwgfx fbdev code is taking
a number of unnecessary modeset locks. In particular the
kms_set_config() function will grab its own locks, leading to
locking retries. So avoid drm_modeset_lock_all() and instead
provide a local acquire context for kms_set_config(). Also have the
vmw_kms_fbdev_init data itself grab the lock that it needs.

This also fixed a long standing problem that vmw_fb_close() didn't
provide an acquire context for kms_set_config(), causing potential
warnings and hangs during driver unload. This problem was uncovered by the
recent commit "drm/vmwgfx: Improve on hibernation"

Testing done:
Repeated driver load and unload on Ubuntu 16.04.2

Fixes: c3b9b1657344 ("drm/vmwgfx: Improve on hibernation")
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
index 2582ffd..ba0cdb7 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
@@ -441,11 +441,11 @@ static int vmwgfx_set_config_internal(struct drm_mode_set *set)
        struct drm_crtc *crtc = set->crtc;
        struct drm_framebuffer *fb;
        struct drm_crtc *tmp;
-       struct drm_modeset_acquire_ctx *ctx;
        struct drm_device *dev = set->crtc->dev;
+       struct drm_modeset_acquire_ctx ctx;
        int ret;
 
-       ctx = dev->mode_config.acquire_ctx;
+       drm_modeset_acquire_init(&ctx, 0);
 
 restart:
        /*
@@ -458,7 +458,7 @@ restart:
 
        fb = set->fb;
 
-       ret = crtc->funcs->set_config(set, ctx);
+       ret = crtc->funcs->set_config(set, &ctx);
        if (ret == 0) {
                crtc->primary->crtc = crtc;
                crtc->primary->fb = fb;
@@ -473,20 +473,13 @@ restart:
        }
 
        if (ret == -EDEADLK) {
-               dev->mode_config.acquire_ctx = NULL;
-
-retry_locking:
-               drm_modeset_backoff(ctx);
-
-               ret = drm_modeset_lock_all_ctx(dev, ctx);
-               if (ret)
-                       goto retry_locking;
-
-               dev->mode_config.acquire_ctx = ctx;
-
+               drm_modeset_backoff(&ctx);
                goto restart;
        }
 
+       drm_modeset_drop_locks(&ctx);
+       drm_modeset_acquire_fini(&ctx);
+
        return ret;
 }
 
@@ -624,7 +617,6 @@ static int vmw_fb_set_par(struct fb_info *info)
        }
 
        mutex_lock(&par->bo_mutex);
-       drm_modeset_lock_all(vmw_priv->dev);
        ret = vmw_fb_kms_framebuffer(info);
        if (ret)
                goto out_unlock;
@@ -657,7 +649,6 @@ out_unlock:
                drm_mode_destroy(vmw_priv->dev, old_mode);
        par->set_mode = mode;
 
-       drm_modeset_unlock_all(vmw_priv->dev);
        mutex_unlock(&par->bo_mutex);
 
        return ret;
@@ -713,18 +704,14 @@ int vmw_fb_init(struct vmw_private *vmw_priv)
        par->max_width = fb_width;
        par->max_height = fb_height;
 
-       drm_modeset_lock_all(vmw_priv->dev);
        ret = vmw_kms_fbdev_init_data(vmw_priv, 0, par->max_width,
                                      par->max_height, &par->con,
                                      &par->crtc, &init_mode);
-       if (ret) {
-               drm_modeset_unlock_all(vmw_priv->dev);
+       if (ret)
                goto err_kms;
-       }
 
        info->var.xres = init_mode->hdisplay;
        info->var.yres = init_mode->vdisplay;
-       drm_modeset_unlock_all(vmw_priv->dev);
 
        /*
         * Create buffers and alloc memory
@@ -832,7 +819,9 @@ int vmw_fb_close(struct vmw_private *vmw_priv)
        cancel_delayed_work_sync(&par->local_work);
        unregister_framebuffer(info);
 
+       mutex_lock(&par->bo_mutex);
        (void) vmw_fb_kms_detach(par, true, true);
+       mutex_unlock(&par->bo_mutex);
 
        vfree(par->vmalloc);
        framebuffer_release(info);

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index f11601b..aacc930 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -2680,7 +2680,9 @@ int vmw_kms_fbdev_init_data(struct vmw_private *dev_priv,
        struct vmw_display_unit *du;
        struct drm_display_mode *mode;
        int i = 0;
+       int ret = 0;
 
+       mutex_lock(&dev_priv->dev->mode_config.mutex);
        list_for_each_entry(con, &dev_priv->dev->mode_config.connector_list,
                            head) {
                if (i == unit)
@@ -2691,7 +2693,8 @@ int vmw_kms_fbdev_init_data(struct vmw_private *dev_priv,
 
        if (i != unit) {
                DRM_ERROR("Could not find initial display unit.\n");
-               return -EINVAL;
+               ret = -EINVAL;
+               goto out_unlock;
        }
 
        if (list_empty(&con->modes))
@@ -2699,7 +2702,8 @@ int vmw_kms_fbdev_init_data(struct vmw_private *dev_priv,
 
        if (list_empty(&con->modes)) {
                DRM_ERROR("Could not find initial display mode.\n");
-               return -EINVAL;
+               ret = -EINVAL;
+               goto out_unlock;
        }
 
        du = vmw_connector_to_du(con);
@@ -2720,7 +2724,10 @@ int vmw_kms_fbdev_init_data(struct vmw_private *dev_priv,
                                           head);
        }
 
-       return 0;
+ out_unlock:
+       mutex_unlock(&dev_priv->dev->mode_config.mutex);
+
+       return ret;
 }
 
 /**