Re: Re: Strange Linux behaviour with blocking syscalls and stopsignals+SIGCONT

From: Linus Torvalds
Date: Fri Jul 07 2006 - 01:09:39 EST




On Fri, 7 Jul 2006, Michael Kerrisk wrote:
> Von: Linus Torvalds <torvalds@xxxxxxxx>
> > On Thu, 6 Jul 2006, Manfred Spraul wrote:
> > >
> > > Is it necessary that the futex syscall ignores SA_RESTART?
> >
> > Very possibly. That was definitely the case for "select()" long ago.
>
> Why was this necesary back then?

I forget the exact details, but certain X applications would stop
responding, because they would restart their select() system call in their
main select-loop, rather than go through the loop.

I _think_ it was SIGALARM installed with SA_RESTART (and doing itimers
every 10 ms), but I didn't really care enough - we had select() return
ERESTARTSYS for exactly one day back in 199x, and when I figured out what
broke, it got reverted pronto.

I want to say that the failing app was "oneko" (damn, I should try to find
if it still exists - brings back memories of an earlier time), but the
point being that it's enough that one app breaks.

Linus
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