List of v4l drRe: Is this in fact a V4L bug introduced in 2.4.19 videodev.c:( was RE: cpia (and OV511) v4l error found

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Here is the list of 2.4.20 drivers broken by the introduction of a lock
in video_unregister_device() in 2.4.19:  (a reboot
and extensive fscking is needed after the user subseqently logs out of an
X-session (and the system hangs), after a usb disconnect while open).   
(This is probably far worse than the effects of the race that was cured!)

All defer unregistering the video_device to the v4l close() funxtion
if the device was unplugged while open.

cpia
ov511
pwc-if
se401
stv680


which driver is a good model for "doing it right" when it comes
to the usb cable being yanked?  maybe usbvideo.c ?

** is  it in fact  necessary to kfree() the video device struct after
unregistering, as pwc-if.c does?  (pwc-if.c appears to believe this
is stopping a memory leak, but no othe driver seems to do it)


On 09-Dec-2002 Alan Cox wrote:
>> Is there any reason for this, or was it just over-zealous lock-adding
>> that actually breaks the procedures for dealing with unplugged
>> open devices?   
> 
> Fixing a race.
> 
>> Could someone test what actually happens when the usb cable is yanked on
>> some other open webcams on 2.4.19 or later?
> 
> You need to remove the cable out of interrupt context, eg using schedule_work
> in 2.5
> 
> 
> 
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----------------------------------
E-Mail: Duncan Haldane <f.duncan.m.haldane@xxxxxxxxxxxxxxxx>
Date: 09-Dec-2002
Time: 12:53:05

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