| Message ID | 1398186535-66539-1-git-send-email-roger.pau@citrix.com |
|---|---|
| State | New |
| Headers | show |
Il 22/04/2014 19:08, Roger Pau Monne ha scritto: > On FreeBSD polling a master pty while the other end is not connected > with G_IO_OUT only results in an endless wait. This is different from > the Linux behaviour, that returns immediately. In order to demonstrate > this, I have the following example code: > > http://xenbits.xen.org/people/royger/test_poll.c > > When executed on Linux: > > $ ./test_poll > In callback > > On FreeBSD instead, the callback never gets called: > > $ ./test_poll > > So, in order to workaround this, poll the source with G_IO_HUP (which > makes the code behave the same way on both Linux and FreeBSD). > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com> > Cc: Michael Tokarev <mjt@tls.msk.ru> > Cc: "Andreas Färber" <afaerber@suse.de> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: xen-devel@lists.xenproject.org > --- > hw/char/serial.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/hw/char/serial.c b/hw/char/serial.c > index 6025592..ab9c40f 100644 > --- a/hw/char/serial.c > +++ b/hw/char/serial.c > @@ -243,7 +243,7 @@ static gboolean serial_xmit(GIOChannel *chan, GIOCondition cond, void *opaque) > serial_receive1(s, &s->tsr, 1); > } else if (qemu_chr_fe_write(s->chr, &s->tsr, 1) != 1) { > if (s->tsr_retry >= 0 && s->tsr_retry < MAX_XMIT_RETRY && > - qemu_chr_fe_add_watch(s->chr, G_IO_OUT, serial_xmit, s) > 0) { > + qemu_chr_fe_add_watch(s->chr, G_IO_OUT|G_IO_HUP, serial_xmit, s) > 0) { > s->tsr_retry++; > return FALSE; > } > The patch looks good. However, the same problem is most likely there in other places: hw/char/cadence_uart.c: int r = qemu_chr_fe_add_watch(s->chr, G_IO_OUT, cadence_uart_xmit, s); hw/char/serial.c: qemu_chr_fe_add_watch(s->chr, G_IO_OUT, serial_xmit, s) > 0) { hw/char/virtio-console.c: vcon->watch = qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT, hw/usb/redirect.c: dev->watch = qemu_chr_fe_add_watch(dev->cs, G_IO_OUT, monitor.c: mon->watch = qemu_chr_fe_add_watch(mon->chr, G_IO_OUT, Should we add G_IO_HUP everywhere we have G_IO_OUT? Or perhaps even in qemu_chr_fe_add_watch (I don't really like this, but I will shoot it out...)? Paolo
On 28/04/14 11:19, Paolo Bonzini wrote: > Il 22/04/2014 19:08, Roger Pau Monne ha scritto: >> On FreeBSD polling a master pty while the other end is not connected >> with G_IO_OUT only results in an endless wait. This is different from >> the Linux behaviour, that returns immediately. In order to demonstrate >> this, I have the following example code: >> >> http://xenbits.xen.org/people/royger/test_poll.c >> >> When executed on Linux: >> >> $ ./test_poll >> In callback >> >> On FreeBSD instead, the callback never gets called: >> >> $ ./test_poll >> >> So, in order to workaround this, poll the source with G_IO_HUP (which >> makes the code behave the same way on both Linux and FreeBSD). >> >> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> >> Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com> >> Cc: Michael Tokarev <mjt@tls.msk.ru> >> Cc: "Andreas Färber" <afaerber@suse.de> >> Cc: Paolo Bonzini <pbonzini@redhat.com> >> Cc: xen-devel@lists.xenproject.org >> --- >> hw/char/serial.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/hw/char/serial.c b/hw/char/serial.c >> index 6025592..ab9c40f 100644 >> --- a/hw/char/serial.c >> +++ b/hw/char/serial.c >> @@ -243,7 +243,7 @@ static gboolean serial_xmit(GIOChannel *chan, GIOCondition cond, void *opaque) >> serial_receive1(s, &s->tsr, 1); >> } else if (qemu_chr_fe_write(s->chr, &s->tsr, 1) != 1) { >> if (s->tsr_retry >= 0 && s->tsr_retry < MAX_XMIT_RETRY && >> - qemu_chr_fe_add_watch(s->chr, G_IO_OUT, serial_xmit, s) > 0) { >> + qemu_chr_fe_add_watch(s->chr, G_IO_OUT|G_IO_HUP, serial_xmit, s) > 0) { >> s->tsr_retry++; >> return FALSE; >> } >> > > The patch looks good. However, the same problem is most likely there > in other places: > > hw/char/cadence_uart.c: int r = qemu_chr_fe_add_watch(s->chr, G_IO_OUT, cadence_uart_xmit, s); > hw/char/serial.c: qemu_chr_fe_add_watch(s->chr, G_IO_OUT, serial_xmit, s) > 0) { This is the one I've fixed. > hw/char/virtio-console.c: vcon->watch = qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT, > hw/usb/redirect.c: dev->watch = qemu_chr_fe_add_watch(dev->cs, G_IO_OUT, > monitor.c: mon->watch = qemu_chr_fe_add_watch(mon->chr, G_IO_OUT, > > Should we add G_IO_HUP everywhere we have G_IO_OUT? IMOH it seems better to add G_IO_HUP to those other callers rather than appending it in qemu_chr_fe_add_watch unconditionally, but I don't have a strong opinion. If no one else expresses an interest into having it added to qemu_chr_fe_add_watch I will send a new version that also fixes the other callers listed above. Roger.
diff --git a/hw/char/serial.c b/hw/char/serial.c index 6025592..ab9c40f 100644 --- a/hw/char/serial.c +++ b/hw/char/serial.c @@ -243,7 +243,7 @@ static gboolean serial_xmit(GIOChannel *chan, GIOCondition cond, void *opaque) serial_receive1(s, &s->tsr, 1); } else if (qemu_chr_fe_write(s->chr, &s->tsr, 1) != 1) { if (s->tsr_retry >= 0 && s->tsr_retry < MAX_XMIT_RETRY && - qemu_chr_fe_add_watch(s->chr, G_IO_OUT, serial_xmit, s) > 0) { + qemu_chr_fe_add_watch(s->chr, G_IO_OUT|G_IO_HUP, serial_xmit, s) > 0) { s->tsr_retry++; return FALSE; }
On FreeBSD polling a master pty while the other end is not connected with G_IO_OUT only results in an endless wait. This is different from the Linux behaviour, that returns immediately. In order to demonstrate this, I have the following example code: http://xenbits.xen.org/people/royger/test_poll.c When executed on Linux: $ ./test_poll In callback On FreeBSD instead, the callback never gets called: $ ./test_poll So, in order to workaround this, poll the source with G_IO_HUP (which makes the code behave the same way on both Linux and FreeBSD). Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com> Cc: Michael Tokarev <mjt@tls.msk.ru> Cc: "Andreas Färber" <afaerber@suse.de> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: xen-devel@lists.xenproject.org --- hw/char/serial.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)