re: increase softint_bytes

[matthew green <mrg%eterna.com.au@localhost>]

Masanobu SAITOH writes:
>   Hi, all.
> 
>   Some device drivers now allocate a lot of softints.
> See:
> 
> 	http://mail-index.netbsd.org/current-users/2017/11/09/msg032581.html
> 
> To avoid this panic, I wrote the following patch:
> 
> 	http://www.netbsd.org/~msaitoh/softint-20171116-0.dif
> 
> Summary:
> 
> 	- Increase the default size from 8192 bytes to 32768 bytes.
> 	- Add new option SOFTINT_BYTES to change the value.
> 	- Add two new read-only sysctls kern.softint.{max,count}
> 
> Any comment?

can't this be fixed by making it dynamic?  ie, fix it properly so
that it never has this problem again -- if in 10 years we're adding
5x as many softints as today, we'll hit it again.

i also don't see why the crash can't be fixed to become an error.
the code tries to avoid adding more than it can, but soemthing must
be wrong for the crash to occur anyway.  ie, at worst we'd fix it
to return an error instead of crashing.

if that is done, the sysctl exports seem unneccesary as well.

thanks.


.mrg.