Re: [PATCH 2/4] set_restore_sigmask TIF_SIGPENDING

Linus Torvalds
2008-03-29T02:52:06Z

On Fri, 28 Mar 2008, Roland McGrath wrote:
>
> It could be a PF_* too, I suppose. There aren't too many of those
> bits free, but it would have the advantage of being a place for an
> arch that doesn't store any TS_* bits anywhere.

Yeah, I guess PF_ would be a bit more regular. Maybe we should even try to
avoid the use of TS_ in x86, and turn it into PF_. There are probably bad
historical reasons for the duplication of capabilities.

> Since acting on the flag is in arch signal code anyway, it makes some
> sense to let the arch define how it gets that to happen. I'll send
> some follow-on patches that change the conditionals to use #ifdef
> HAVE_SET_RESTORE_SIGMASK.

Let's see if it matters first. No reason to add another arch-specific
thing if nobody can even measure this thing, and from a quick look it
seems like every RESTORE_SIGMASK user is basically an error path for a
system call. Those few extra cycles really won't be noticeable, we almost
certainly have better things we could use our energy on.

So never mind. I think your series is fine, and my TS_ idea doesn't really
look like it's worth it (and using PF_ sounds a bit more palatable since
we could do it with existing infrastructure, but a quick grep shows that
there's more users of test_thread_flag(TIF_RESTORE_SIGMASK) than I would
have expected (and the *testing* is equally cheap for atomic and thread-
synchronous fields, so that's not a performance issue).

Linus