Il 12/11/2013 12:53, Laszlo Ersek ha scritto:
> Also, I grepped the source for SIGWINCH, and I think it is never masked
> with pthread_sigmask(), or -- while the process is single-threaded
> initially -- with sigprocmask(). Hence this signal can be delivered at
> any time and interrupt interruptible functions (which is good
> justification for the patch.) My point though is that after this patch a
> narrow window seems to exist where you can lose a signal, namely between
> checking "got_sigwinch" and resetting it.
You don't really lose it, it is delayed to the next refresh.
> (SIGWINCH is not a standard signal but I do think it it's not a realtime
> one, hence it doesn't queue up; it can only be pending or not.)
Indeed.
> For ultimate pedantry we could maybe write
>
> bool local;
>
> /* block the signal with pthread_sigmask()
> * for atomic retrieval and reset
> */
> local = got_sigwinch;
> got_sigwinch = false;
> /* unblock the signal */
>
> if (!local) {
> return;
> }
>
> but it's likely overkill.
Or just use an atomic function:
if (!atomic_xchg(&got_sigwinch, false)) {
return;
}
Paolo
