Bug#991639: udev: 80-debian-compat.rules can yield non-stable and inconsistent symlinks

[Michael Biebl]

Am 29.07.21 um 16:33 schrieb Vincent Lefevre:
> On 2021-07-29 16:20:48 +0200, Michael Biebl wrote:
>> Am 29.07.21 um 15:07 schrieb Vincent Lefevre:
>>> Package: udev
>>> Version: 247.3-6
>>> Severity: normal
>>>
>>> My machine has 2 DVD-RW drives, and /lib/udev/rules.d/80-debian-compat.rules
>>> sometimes yields the following symlinks:
>>>
>>> lrwxrwxrwx 1 root root 3 2021-07-29 14:25:55 /dev/cdrw -> sr1
>>> lrwxrwxrwx 1 root root 3 2021-07-29 14:25:55 /dev/dvd -> sr0
>>> lrwxrwxrwx 1 root root 3 2021-07-29 14:25:55 /dev/dvdrw -> sr0
>>>
>>> instead of /dev/cdrw -> sr0 for the first one, to be consistent with
>>> the other symlinks.
>>>
>>> I already reported the issue in 2017 (4 years ago!), but nothing has
>>> been done yet. See
>>>
>>> * Initial message:
>>>     https://lists.debian.org/debian-user/2017/04/msg00789.html
>>
>>
>> And the comment from 2017 still holds true:
>> https://lists.debian.org/debian-user/2017/04/msg00790.html
>>
>> "
>> See the comment in there:
>>
>> # These rules will create symlinks for CD/DVD drives, to help old
>> # programs which are unable to automatically discover the devices.
>> # The first detected device gets the symlink, but this is not stable across
>> # reboots.
>>
>> So, yes, what you see can happen depending on the order devices are
>> discovered.
>> "
>>
>> The kernel hasn't changed. It still probes devices asynchronously.
>> There is not much we can do about that.
> 
> The comment says: "The first detected device gets the symlink".
> If this were true, all symlinks would be the same (even though
> this would not be stable), which is not the case.
> 
> BTW, aren't the devices numbered 0, 1, etc. in the order they are
> detected, so that one would expect always sr0 here?

It appears you do not believe what I said. Feel free to propose a patch.


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