On Thu, Sep 10, 2015 at 14:22:49 +0100, Alex Bennée wrote:
> Emilio G. Cota <c...@braap.org> writes:
>
> > Signed-off-by: Emilio G. Cota <c...@braap.org>
> > ---
> > util/qemu-thread-posix.c | 11 ++++++++++-
> > 1 file changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
> > index 04dae0f..3760e27 100644
> > --- a/util/qemu-thread-posix.c
> > +++ b/util/qemu-thread-posix.c
> > @@ -303,7 +303,16 @@ static inline void futex_wake(QemuEvent *ev, int n)
> >
> > static inline void futex_wait(QemuEvent *ev, unsigned val)
> > {
> > - futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0);
> > + while (futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0)) {
> > + switch (errno) {
> > + case EWOULDBLOCK:
> > + return;
> > + case EINTR:
> > + break; /* get out of switch and retry */
> > + default:
> > + abort();
>
> I'd be tempted to error_exit with the errno in this case so additional
> information is reported before we bail out.
Yes that's a good suggestion.
> The man pages seems to indicate other errnos are possible for FUTUX_WAIT
> although they may be unlikely:
>
> EACCES No read access to futex memory.
> EFAULT Error retrieving timeout information from user space.
>
> I guess things would have gone very wrong for these
>
> EINVAL Invalid argument.
>
> Hard to get wrong
>
> ENFILE The system limit on the total number of open files has
> been reached.
>
> Might happen under system load?
>
> ENOSYS Invalid operation specified in op.
>
> Hardcoded op so no
>
> ETIMEDOUT
> Timeout during the FUTEX_WAIT operation.
>
> No timeout specified so we shouldn't hit it
Of these I'd say all would be bugs in our code except for ENFILE, so
it might be worth adding.
Thanks,
Emilio
