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

From: Michael Kerrisk
Date: Fri Jul 07 2006 - 01:06:01 EST


Von: Ulrich Drepper <drepper@xxxxxxxxxx>

> sem_wait() is another case. Here the EINTR handling is exposed to the
> programmer. Currently, as I understand it, even SA_RESTART handlers
> cause EINTR to be returned.

Yes, this is true for sem_wait().

> Yes, this usually correct but it might
> disrupt existing code.
>
> This is why I'd caution anybody who thinks about changing something in
> this area. *I* could live with it, I can fix and recompile all the code
> I use. But others aren't that lucky.

Yes; this is why I'm only proposing to change EINTR to ERESTARTNOHAND
at the moment. The only userspace visible change that I think
this will bring about is in the stop+SIGCONT case. Changing EINTR
to ERESTARTSYS is likely to have more impact on userland (though
it still strikes me as a desirable gola to have all system calls
restartable via SA_RESTART).

Cheers,

Michael
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