Re: [PATCH 07/14] ALSA: emu10k1: properly assert DSP init constraints

[Oswald Buddenhagen <oswald.buddenhagen@gmx.de>]

On Fri, May 12, 2023 at 09:15:17AM +0200, Takashi Iwai wrote:
>On Wed, 10 May 2023 19:39:10 +0200,
>Oswald Buddenhagen wrote:
>> 
>> If these are hit, we've already trashed kernel memory by writing past
>> the end of the allocated buffer. There is no recovery from that.
>> 
>Again, this is NAK.

>First of all, if we really do care the overflow
>seriously, we should check at each increment instead of after
>breakage.  It shouldn't be too difficult at all.
>
not difficult, but pointless bloat.

>Second, using BUG_ON() like this case is an overkill.  It was clearly
>stated by Linus in the past a few times (although I can't find the
>source right now).
>
you seem to have an irrational aversion against assertions, maybe 
because linus likes to scream at people.

relevant comments from linus were easy enough to find:
https://yarchive.net/comp/linux/BUG.html
https://lore.kernel.org/all/CA+55aFwyNTLuZgOWMTRuabWobF27ygskuxvFd-P0n-3UNT=0Og@mail.gmail.com/T/#u

and there is also the documentation on BUG() itself.

i don't see anything in either of these that would imply that my use of 
BUG_ON() is inappropriate. it catches a serious programming error, is 
easy to prove correct (the scope is a single function), and the only 
immediate effect is that it will crash the insmod process (though i 
would expect possible followup effects due to the kernel memory 
corruption, which is exactly why the assert is there). i have a hard 
time thinking of a *more* appropriate use for BUG().

regards