Hi,
On 29-05-17 21:02, Daniel Vetter wrote:
On Sun, May 28, 2017 at 07:16:55PM +0200, Hans de Goede wrote:
Since commit a39be606f99d ("drm: Do a full device unregister when
unplugging") drm_unplug_dev has been calling drm_dev_unregister followed
by a drm_put_dev when open_count reaches 0. This drm_put_dev calls
drm_dev_unregister again. Since drm_dev_unregister is not protected
against being called multiple times this leads to havoc.
This commit fixes this by calling drm_dev_unref instead of drm_put_dev.
Fixes: a39be606f99d ("drm: Do a full device unregister when unplugging")
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Marco Diego Aurélio Mesquita <marcodiegomesquita@xxxxxxxxx>
Reported-by: Marco Diego Aurélio Mesquita <marcodiegomesquita@xxxxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Note I don't have any USB display devices at hand for testing atm so
this patch has only been compile tested.
---
Changes in v2:
-Remove unnecessary mutex changes
Offending patch is in 4.8 ... do we need cc: stable?
Yes I think a Cc: stable would be good.
Does this need a bugreport link?
There is no bug-report that I know of (Marco reported the issues
to me by email). This likely fixes some crashes when unplugging
USB display link devices.
Note I plan to actually test this patch with an USB display device
tomorrow, so you may want to hold on merging this till I've got
around to testing this.
Regards,
Hans
---
drivers/gpu/drm/drm_drv.c | 6 +++---
drivers/gpu/drm/drm_file.c | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index b5c6bb46a425..30b5382bf877 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -364,9 +364,9 @@ void drm_unplug_dev(struct drm_device *dev)
drm_device_set_unplugged(dev);
- if (dev->open_count == 0) {
- drm_put_dev(dev);
- }
+ if (dev->open_count == 0)
+ drm_dev_unref(dev);
+
mutex_unlock(&drm_global_mutex);
}
EXPORT_SYMBOL(drm_unplug_dev);
diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index 3783b659cd38..edba71c8ccc3 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -424,7 +424,7 @@ int drm_release(struct inode *inode, struct file *filp)
if (!--dev->open_count) {
drm_lastclose(dev);
if (drm_device_is_unplugged(dev))
- drm_put_dev(dev);
+ drm_dev_unref(dev);
}
mutex_unlock(&drm_global_mutex);
--
2.13.0
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