Re: [GIT PULL] core/urgent for v5.16-rc6

[Linus Torvalds]

On Mon, Dec 20, 2021 at 8:20 AM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Whatever. I don't care that much, but this all smells like you just
> dug your own hole for very questionable causes, and instead of a
> "don't do that then" this all is doubling down on a bad idea.

It further looks like it's really only the sas_ss_size that is
checked, so if people wan tto have a lock, make it clear that's the
only thing that the lock is about.

So the actual "do I even need to lock" condition should likely just be

        if (ss_size < t->sas_ss_size)
                .. don't bother locking ..

but as mentioned, I don't really see much of a point in being so
careful even about the growing case.

If somebody is changing xstate features concurrently with another
thread setting up their altstack, they can keep both pieces.

                 Linus