[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] serial: poll the serial console with G_IO_HUP
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 Monnà <roger.pau@xxxxxxxxxx> >> Cc: Peter Crosthwaite <peter.crosthwaite@xxxxxxxxxx> >> Cc: Michael Tokarev <mjt@xxxxxxxxxx> >> Cc: "Andreas FÃrber" <afaerber@xxxxxxx> >> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> >> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx >> --- >> 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. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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