Re: [Qemu-devel] [PATCH] net: tap: use qemu_set_nonblock

[Daniel P . Berrangé]

On Wed, Nov 21, 2018 at 03:28:29PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Wed, Nov 21, 2018 at 3:22 PM Li Qiang <address@hidden> wrote:
> >
> > The fcntl will change the flags directly, use qemu_set_nonblock()
> > instead.
> 
> qemu_set_nonblock() will preserve the existing flags. And on windows,
> it will register the FD to the event loop.
> that's a reasonable thing to do, is this fixing an actual bug?

tap.c is only built with CONFIG_POSIX. Win32 is completely separate
in tap-win32.c.  So the event loop reg doesn't apply.

I agree it is good to preserve fcntl flags though, so this patch
looks desirable.

Reviewed-by: Daniel P. Berrangé <address@hidden>


> 
> >
> > Signed-off-by: Li Qiang <address@hidden>
> > ---
> >  net/tap.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/net/tap.c b/net/tap.c
> > index cc8525f154..e8aadd8d4b 100644
> > --- a/net/tap.c
> > +++ b/net/tap.c
> > @@ -592,7 +592,7 @@ int net_init_bridge(const Netdev *netdev, const char 
> > *name,
> >          return -1;
> >      }
> >
> > -    fcntl(fd, F_SETFL, O_NONBLOCK);
> > +    qemu_set_nonblock(fd);
> >      vnet_hdr = tap_probe_vnet_hdr(fd);
> >      s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
> >
> > @@ -707,7 +707,7 @@ static void net_init_tap_one(const NetdevTapOptions 
> > *tap, NetClientState *peer,
> >                  }
> >                  return;
> >              }
> > -            fcntl(vhostfd, F_SETFL, O_NONBLOCK);
> > +            qemu_set_nonblock(vhostfd);
> >          }
> >          options.opaque = (void *)(uintptr_t)vhostfd;
> >
> > @@ -791,7 +791,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
> >              return -1;
> >          }
> >
> > -        fcntl(fd, F_SETFL, O_NONBLOCK);
> > +        qemu_set_nonblock(fd);
> >
> >          vnet_hdr = tap_probe_vnet_hdr(fd);
> >
> > @@ -839,7 +839,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
> >                  goto free_fail;
> >              }
> >
> > -            fcntl(fd, F_SETFL, O_NONBLOCK);
> > +            qemu_set_nonblock(fd);
> >
> >              if (i == 0) {
> >                  vnet_hdr = tap_probe_vnet_hdr(fd);
> > @@ -887,7 +887,7 @@ free_fail:
> >              return -1;
> >          }
> >
> > -        fcntl(fd, F_SETFL, O_NONBLOCK);
> > +        qemu_set_nonblock(fd);
> >          vnet_hdr = tap_probe_vnet_hdr(fd);
> >
> >          net_init_tap_one(tap, peer, "bridge", name, ifname,
> > --
> > 2.11.0
> >
> >
> 
> 
> -- 
> Marc-André Lureau
> 

Regards,
Daniel
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