Re: [Qemu-devel] [PATCH 2/2] io: fix qio_channel_socket_accept err handling

[Peter Xu]

On Wed, Aug 02, 2017 at 10:30:20AM +0100, Daniel P. Berrange wrote:
> On Wed, Aug 02, 2017 at 11:25:21AM +0800, Peter Xu wrote:
> > When accept failed, we should setup errp with the reason. More
> > importantly, the caller may assume errp be non-NULL when error happens,
> > and not setting the errp may crash QEMU.
> > 
> > At the same time, move the trace_qio_channel_socket_accept_fail() after
> > the if check on EINTR. Two reasons:
> > 
> > 1. when EINTR happened, it's not really a fault (we should just try
> >    again), so we should not log with an "accept failure".
> > 
> > 2. trace_*() functions may overwrite errno, then the old errno will be
> >    missing. We need to either check errno before trace_*() calls, or
> >    reserve the errno.
> > 
> > Signed-off-by: Peter Xu <address@hidden>
> > ---
> >  io/channel-socket.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/io/channel-socket.c b/io/channel-socket.c
> > index 53386b7..442f230 100644
> > --- a/io/channel-socket.c
> > +++ b/io/channel-socket.c
> > @@ -340,10 +340,11 @@ qio_channel_socket_accept(QIOChannelSocket *ioc,
> >      cioc->fd = qemu_accept(ioc->fd, (struct sockaddr *)&cioc->remoteAddr,
> >                             &cioc->remoteAddrLen);
> >      if (cioc->fd < 0) {
> > -        trace_qio_channel_socket_accept_fail(ioc);
> >          if (errno == EINTR) {
> >              goto retry;
> >          }
> > +        trace_qio_channel_socket_accept_fail(ioc);
> > +        error_setg_errno(errp, errno, "Unable to accept connection");
> 
> Err, you're still clobbering errno in trace_qio_channel_socket_accept_fail
> before calling error_setg_errno

Oops! I'll do a quick respin.  Thanks for pointing out.

-- 
Peter Xu