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author | 2018-10-08 12:57:34 +0200 | |
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committer | 2018-10-08 12:57:34 +0200 | |
commit | 68a958a915ca912b8ce71b9eea7445996f6e681e (patch) | |
tree | 23476581d14a94613b449d7536f71a9511d6638f /include/video/udlfb.h | |
parent | video: fbdev: add the dependency of broadsheetfb in Kconfig (diff) | |
download | linux-68a958a915ca912b8ce71b9eea7445996f6e681e.tar.gz linux-68a958a915ca912b8ce71b9eea7445996f6e681e.tar.bz2 linux-68a958a915ca912b8ce71b9eea7445996f6e681e.zip |
udlfb: handle unplug properly
The udlfb driver maintained an open count and cleaned up itself when the
count reached zero. But the console is also counted in the reference count
- so, if the user unplugged the device, the open count would not drop to
zero and the driver stayed loaded with console attached. If the user
re-plugged the adapter, it would create a device /dev/fb1, show green
screen and the access to the console would be lost.
The framebuffer subsystem has reference counting on its own - in order to
fix the unplug bug, we rely the framebuffer reference counting. When the
user unplugs the adapter, we call unregister_framebuffer unconditionally.
unregister_framebuffer will unbind the console, wait until all users stop
using the framebuffer and then call the fb_destroy method. The fb_destroy
cleans up the USB driver.
This patch makes the following changes:
* Drop dlfb->kref and rely on implicit framebuffer reference counting
instead.
* dlfb_usb_disconnect calls unregister_framebuffer, the rest of driver
cleanup is done in the function dlfb_ops_destroy. dlfb_ops_destroy will
be called by the framebuffer subsystem when no processes have the
framebuffer open or mapped.
* We don't use workqueue during initialization, but initialize directly
from dlfb_usb_probe. The workqueue could race with dlfb_usb_disconnect
and this racing would produce various kinds of memory corruption.
* We use usb_get_dev and usb_put_dev to make sure that the USB subsystem
doesn't free the device under us.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
cc: Dave Airlie <airlied@redhat.com>
Cc: Bernie Thompson <bernie@plugable.com>,
Cc: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Diffstat (limited to 'include/video/udlfb.h')
-rw-r--r-- | include/video/udlfb.h | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/include/video/udlfb.h b/include/video/udlfb.h index 3abd327bada6..7d09e54ae54e 100644 --- a/include/video/udlfb.h +++ b/include/video/udlfb.h @@ -36,12 +36,9 @@ struct dlfb_data { struct usb_device *udev; struct fb_info *info; struct urb_list urbs; - struct kref kref; char *backing_buffer; int fb_count; bool virtualized; /* true when physical usb device not present */ - struct delayed_work init_framebuffer_work; - struct delayed_work free_framebuffer_work; atomic_t usb_active; /* 0 = update virtual buffer, but no usb traffic */ atomic_t lost_pixels; /* 1 = a render op failed. Need screen refresh */ char *edid; /* null until we read edid from hw or get from sysfs */ |