* [Qemu-devel] [PATCH 1/1] serial: Open non-block
@ 2018-02-26 13:04 Dr. David Alan Gilbert (git)
2018-02-26 13:57 ` Paolo Bonzini
2018-06-29 14:36 ` Paolo Bonzini
0 siblings, 2 replies; 4+ messages in thread
From: Dr. David Alan Gilbert (git) @ 2018-02-26 13:04 UTC (permalink / raw)
To: qemu-devel, pbonzini, marcandre.lureau
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
On a real serial device, the open can block if the handshake
lines are in a particular state. If a QEMU is passing the serial
device to the guest, the QEMU startup is blocked opening the device
(with a symptom seen as a timeout from libvirt).
Open the serial port with O_NONBLOCK.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
chardev/char-serial.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/chardev/char-serial.c b/chardev/char-serial.c
index feb52e559d..97be5d4a63 100644
--- a/chardev/char-serial.c
+++ b/chardev/char-serial.c
@@ -265,7 +265,8 @@ static void qmp_chardev_open_serial(Chardev *chr,
ChardevHostdev *serial = backend->u.serial.data;
int fd;
- fd = qmp_chardev_open_file_source(serial->device, O_RDWR, errp);
+ fd = qmp_chardev_open_file_source(serial->device, O_RDWR | O_NONBLOCK,
+ errp);
if (fd < 0) {
return;
}
--
2.14.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH 1/1] serial: Open non-block
2018-02-26 13:04 [Qemu-devel] [PATCH 1/1] serial: Open non-block Dr. David Alan Gilbert (git)
@ 2018-02-26 13:57 ` Paolo Bonzini
2018-02-26 15:13 ` Dr. David Alan Gilbert
2018-06-29 14:36 ` Paolo Bonzini
1 sibling, 1 reply; 4+ messages in thread
From: Paolo Bonzini @ 2018-02-26 13:57 UTC (permalink / raw)
To: Dr. David Alan Gilbert (git), qemu-devel, marcandre.lureau
On 26/02/2018 14:04, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> On a real serial device, the open can block if the handshake
> lines are in a particular state. If a QEMU is passing the serial
> device to the guest, the QEMU startup is blocked opening the device
> (with a symptom seen as a timeout from libvirt).
>
> Open the serial port with O_NONBLOCK.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Socket chardevs have "nowait" for that. Should serial have something
similar?
Thanks,
Paolo
> ---
> chardev/char-serial.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/chardev/char-serial.c b/chardev/char-serial.c
> index feb52e559d..97be5d4a63 100644
> --- a/chardev/char-serial.c
> +++ b/chardev/char-serial.c
> @@ -265,7 +265,8 @@ static void qmp_chardev_open_serial(Chardev *chr,
> ChardevHostdev *serial = backend->u.serial.data;
> int fd;
>
> - fd = qmp_chardev_open_file_source(serial->device, O_RDWR, errp);
> + fd = qmp_chardev_open_file_source(serial->device, O_RDWR | O_NONBLOCK,
> + errp);
> if (fd < 0) {
> return;
> }
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH 1/1] serial: Open non-block
2018-02-26 13:57 ` Paolo Bonzini
@ 2018-02-26 15:13 ` Dr. David Alan Gilbert
0 siblings, 0 replies; 4+ messages in thread
From: Dr. David Alan Gilbert @ 2018-02-26 15:13 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: qemu-devel, marcandre.lureau
* Paolo Bonzini (pbonzini@redhat.com) wrote:
> On 26/02/2018 14:04, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> > On a real serial device, the open can block if the handshake
> > lines are in a particular state. If a QEMU is passing the serial
> > device to the guest, the QEMU startup is blocked opening the device
> > (with a symptom seen as a timeout from libvirt).
> >
> > Open the serial port with O_NONBLOCK.
> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
> Socket chardevs have "nowait" for that. Should serial have something
> similar?
Hmm, maybe, although I think for real serial the nonblocking open should
be the default.
I've not got any more complex tests though for it.
stty -F uses the same trick of opening non-blocking.
Dave
> Thanks,
>
> Paolo
>
> > ---
> > chardev/char-serial.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/chardev/char-serial.c b/chardev/char-serial.c
> > index feb52e559d..97be5d4a63 100644
> > --- a/chardev/char-serial.c
> > +++ b/chardev/char-serial.c
> > @@ -265,7 +265,8 @@ static void qmp_chardev_open_serial(Chardev *chr,
> > ChardevHostdev *serial = backend->u.serial.data;
> > int fd;
> >
> > - fd = qmp_chardev_open_file_source(serial->device, O_RDWR, errp);
> > + fd = qmp_chardev_open_file_source(serial->device, O_RDWR | O_NONBLOCK,
> > + errp);
> > if (fd < 0) {
> > return;
> > }
> >
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH 1/1] serial: Open non-block
2018-02-26 13:04 [Qemu-devel] [PATCH 1/1] serial: Open non-block Dr. David Alan Gilbert (git)
2018-02-26 13:57 ` Paolo Bonzini
@ 2018-06-29 14:36 ` Paolo Bonzini
1 sibling, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2018-06-29 14:36 UTC (permalink / raw)
To: Dr. David Alan Gilbert (git), qemu-devel, marcandre.lureau
On 26/02/2018 14:04, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> On a real serial device, the open can block if the handshake
> lines are in a particular state. If a QEMU is passing the serial
> device to the guest, the QEMU startup is blocked opening the device
> (with a symptom seen as a timeout from libvirt).
>
> Open the serial port with O_NONBLOCK.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> chardev/char-serial.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/chardev/char-serial.c b/chardev/char-serial.c
> index feb52e559d..97be5d4a63 100644
> --- a/chardev/char-serial.c
> +++ b/chardev/char-serial.c
> @@ -265,7 +265,8 @@ static void qmp_chardev_open_serial(Chardev *chr,
> ChardevHostdev *serial = backend->u.serial.data;
> int fd;
>
> - fd = qmp_chardev_open_file_source(serial->device, O_RDWR, errp);
> + fd = qmp_chardev_open_file_source(serial->device, O_RDWR | O_NONBLOCK,
> + errp);
> if (fd < 0) {
> return;
> }
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-02-26 13:04 [Qemu-devel] [PATCH 1/1] serial: Open non-block Dr. David Alan Gilbert (git)
2018-02-26 13:57 ` Paolo Bonzini
2018-02-26 15:13 ` Dr. David Alan Gilbert
2018-06-29 14:36 ` Paolo Bonzini
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