Re: RFC: remove set_fs for m68k

Michael Schmitz
2021-07-16T02:03:14Z

Hi Christoph,

On 15/07/21 7:26 am, Michael Schmitz wrote:
> I've got a vague recollection that I've seen weird crashes in the past
> related to temperature extremes (we've had a few unusually cold days
> in our parts just now), so I've gone back to a kernel from the switch
> stack / refactoring exit tests (which ran the stress tests fine
> earlier) to rule that one out. Looking good so far, so I begin to
> wonder whether we need to introduce get_fc() and use that to restore
> the original sfc/dfc instead of assuming USER_DATA is always correct?

No crashes with the known good kernel after over a day of stress testing
- I'll try Andreas' patch once the current test run has completed.

One thing I noticed with either your final or your v2 patch series - as
far as the tests ran at all, run times were 30% increased. That's a lot
more than I would have expected. Large byte size user copies were
already handled by the code in arch/m68k/lib/uaccess.c which wasn't
explicitly inlined though the calling raw_copy_to/from_user() was. Could
the change to no longer inline raw_copy_to/from_user() have such a large
impact?

Cheers,

Michael