Re: [RFC][PATCH] KGDB: remove kgdb-own fault handling

Jason Wessel
2008-02-08T22:17:57Z

Linus Torvalds wrote:
> On Fri, 8 Feb 2008, Jan Kiszka wrote:
>
>> Well, let's try it this way: Find below a patch against kgdb.git that
>> removes the special fault handling (this wouldn't be the first feature I
>> recently removed from kgdb :->). Light testing revealed no obvious
>> problems yet.
>>
>
> That is indeed horrible code. No way will I merge anything that has things
> like that even in it's *history* (ie somebody needs to re-generate the
> tree without code like that - some things should not be allowed to exist).
>
>

I concur. I will collapse the entire kgdb tree back to the original few
patches which can be bisected.

> That said, while just using "probe_kernel_addr()" is certainly much
> better, it's still really inefficient. If you actually want to do a "safe
> memory copy", then the right way to do that is basically to do
>
> pagefault_disable();
> leftover = __copy_from_user_inatomic(dst, src, count);
> pagefault_enable();
>
> if (leftover)
> handle_the_fact_that_the_copy_didnt_complete();
>
>

Duly Noted. Further cleanups are in progress.

Thanks,
Jason.