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Subject[PATCH 4.19 122/639] drm/fb-helper: generic: Fix setup error path
Date
From: Noralf Trønnes <noralf@tronnes.org>

[ Upstream commit 6e1490cf439aa86b104e5124c36275b964238e1f ]

If register_framebuffer() fails during fbdev setup we will leak the
framebuffer, the GEM buffer and the shadow buffer for defio. This is
because drm_fb_helper_fbdev_setup() just calls drm_fb_helper_fini() on
error not taking into account that register_framebuffer() can fail.

Since the generic emulation uses DRM client for its framebuffer and
backing buffer in addition to a shadow buffer, it's necessary to open code
drm_fb_helper_fbdev_setup() to properly handle the error path.

Error cleanup is removed from .fb_probe and is handled by one function for
all paths.

Fixes: 9060d7f49376 ("drm/fb-helper: Finish the generic fbdev emulation")
Reported-by: Peter Wu <peter@lekensteyn.nl>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190105181846.26495-1-noralf@tronnes.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/drm_fb_helper.c | 98 +++++++++++++++++++--------------
1 file changed, 58 insertions(+), 40 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index f57fc1450b613..1c87ad6667e73 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -2979,18 +2979,16 @@ static int drm_fbdev_fb_release(struct fb_info *info, int user)
return 0;
}

-/*
- * fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
- * unregister_framebuffer() or fb_release().
- */
-static void drm_fbdev_fb_destroy(struct fb_info *info)
+static void drm_fbdev_cleanup(struct drm_fb_helper *fb_helper)
{
- struct drm_fb_helper *fb_helper = info->par;
struct fb_info *fbi = fb_helper->fbdev;
struct fb_ops *fbops = NULL;
void *shadow = NULL;

- if (fbi->fbdefio) {
+ if (!fb_helper->dev)
+ return;
+
+ if (fbi && fbi->fbdefio) {
fb_deferred_io_cleanup(fbi);
shadow = fbi->screen_buffer;
fbops = fbi->fbops;
@@ -3004,6 +3002,12 @@ static void drm_fbdev_fb_destroy(struct fb_info *info)
}

drm_client_framebuffer_delete(fb_helper->buffer);
+}
+
+static void drm_fbdev_release(struct drm_fb_helper *fb_helper)
+{
+ drm_fbdev_cleanup(fb_helper);
+
/*
* FIXME:
* Remove conditional when all CMA drivers have been moved over to using
@@ -3015,6 +3019,15 @@ static void drm_fbdev_fb_destroy(struct fb_info *info)
}
}

+/*
+ * fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
+ * unregister_framebuffer() or fb_release().
+ */
+static void drm_fbdev_fb_destroy(struct fb_info *info)
+{
+ drm_fbdev_release(info->par);
+}
+
static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
struct drm_fb_helper *fb_helper = info->par;
@@ -3065,7 +3078,6 @@ int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
struct drm_framebuffer *fb;
struct fb_info *fbi;
u32 format;
- int ret;

DRM_DEBUG_KMS("surface width(%d), height(%d) and bpp(%d)\n",
sizes->surface_width, sizes->surface_height,
@@ -3082,10 +3094,8 @@ int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
fb = buffer->fb;

fbi = drm_fb_helper_alloc_fbi(fb_helper);
- if (IS_ERR(fbi)) {
- ret = PTR_ERR(fbi);
- goto err_free_buffer;
- }
+ if (IS_ERR(fbi))
+ return PTR_ERR(fbi);

fbi->par = fb_helper;
fbi->fbops = &drm_fbdev_fb_ops;
@@ -3116,8 +3126,7 @@ int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
if (!fbops || !shadow) {
kfree(fbops);
vfree(shadow);
- ret = -ENOMEM;
- goto err_fb_info_destroy;
+ return -ENOMEM;
}

*fbops = *fbi->fbops;
@@ -3129,13 +3138,6 @@ int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
}

return 0;
-
-err_fb_info_destroy:
- drm_fb_helper_fini(fb_helper);
-err_free_buffer:
- drm_client_framebuffer_delete(buffer);
-
- return ret;
}
EXPORT_SYMBOL(drm_fb_helper_generic_probe);

@@ -3147,18 +3149,11 @@ static void drm_fbdev_client_unregister(struct drm_client_dev *client)
{
struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);

- if (fb_helper->fbdev) {
- drm_fb_helper_unregister_fbi(fb_helper);
+ if (fb_helper->fbdev)
/* drm_fbdev_fb_destroy() takes care of cleanup */
- return;
- }
-
- /* Did drm_fb_helper_fbdev_setup() run? */
- if (fb_helper->dev)
- drm_fb_helper_fini(fb_helper);
-
- drm_client_release(client);
- kfree(fb_helper);
+ drm_fb_helper_unregister_fbi(fb_helper);
+ else
+ drm_fbdev_release(fb_helper);
}

static int drm_fbdev_client_restore(struct drm_client_dev *client)
@@ -3174,7 +3169,7 @@ static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
struct drm_device *dev = client->dev;
int ret;

- /* If drm_fb_helper_fbdev_setup() failed, we only try once */
+ /* Setup is not retried if it has failed */
if (!fb_helper->dev && fb_helper->funcs)
return 0;

@@ -3184,15 +3179,34 @@ static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
if (!dev->mode_config.num_connector)
return 0;

- ret = drm_fb_helper_fbdev_setup(dev, fb_helper, &drm_fb_helper_generic_funcs,
- fb_helper->preferred_bpp, 0);
- if (ret) {
- fb_helper->dev = NULL;
- fb_helper->fbdev = NULL;
- return ret;
- }
+ drm_fb_helper_prepare(dev, fb_helper, &drm_fb_helper_generic_funcs);
+
+ ret = drm_fb_helper_init(dev, fb_helper, dev->mode_config.num_connector);
+ if (ret)
+ goto err;
+
+ ret = drm_fb_helper_single_add_all_connectors(fb_helper);
+ if (ret)
+ goto err_cleanup;
+
+ if (!drm_drv_uses_atomic_modeset(dev))
+ drm_helper_disable_unused_functions(dev);
+
+ ret = drm_fb_helper_initial_config(fb_helper, fb_helper->preferred_bpp);
+ if (ret)
+ goto err_cleanup;

return 0;
+
+err_cleanup:
+ drm_fbdev_cleanup(fb_helper);
+err:
+ fb_helper->dev = NULL;
+ fb_helper->fbdev = NULL;
+
+ DRM_DEV_ERROR(dev->dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
+
+ return ret;
}

static const struct drm_client_funcs drm_fbdev_client_funcs = {
@@ -3245,6 +3259,10 @@ int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)

drm_client_add(&fb_helper->client);

+ if (!preferred_bpp)
+ preferred_bpp = dev->mode_config.preferred_depth;
+ if (!preferred_bpp)
+ preferred_bpp = 32;
fb_helper->preferred_bpp = preferred_bpp;

drm_fbdev_client_hotplug(&fb_helper->client);
--
2.20.1


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