From: Amit Shah <amit.shah@redhat.com>
To: Paul Brook <paul@codesourcery.com>
Cc: Juan Quintela <quintela@redhat.com>,
qemu-devel@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes
Date: Tue, 6 Apr 2010 08:54:29 +0530 [thread overview]
Message-ID: <20100406032429.GB4135@amit-x200.redhat.com> (raw)
In-Reply-To: <201004051733.38629.paul@codesourcery.com>
On (Mon) Apr 05 2010 [17:33:38], Paul Brook wrote:
> > There might be cases where a few bytes would have been sent out to char
> > devices and some not. Currently the return values from qemu_chr_write()
> > to char devs are only -1, indicating an error, or the complete length
> > of the string passed.
> >
> > Make 'len' a pointer instead, and indicate how much of the string was
> > written. The return value will either be the same as 'len' or a negative
> > number indicating an error condition.
>
> This seems wrong. We should not be getting recoverable errors.
I was thinking of adding a bool to CharDriverState to indicate if EAGAIN
should be reported to the writer. This can be conveyed at the time of
doing qemu_chr_add_handlers().
It would certainly be beneficial for consumers of virtio-serial to be
notified of -EAGAIN so that the guest can be throttled till the chardev
catches up with the data being sent.
Amit
next prev parent reply other threads:[~2010-04-06 3:26 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-05 12:45 [Qemu-devel] [PATCH 0/5] chardev, virtio-console: flow control, error handling Amit Shah
2010-04-05 12:45 ` [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes Amit Shah
2010-04-05 12:45 ` [Qemu-devel] [PATCH 2/5] char: unix write: Add some sleep to ease off spinning in a tight loop Amit Shah
2010-04-05 12:45 ` [Qemu-devel] [PATCH 3/5] char: unix: For files that are nonblocking, report -EAGAIN to calling functions Amit Shah
2010-04-05 12:45 ` [Qemu-devel] [PATCH 4/5] virtio-console: Factor out common init between console and generic ports Amit Shah
2010-04-05 12:45 ` [Qemu-devel] [PATCH 5/5] virtio-console: Throttle virtio-serial-bus if we can't consume any more guest data Amit Shah
2010-04-06 7:45 ` [Qemu-devel] " Gerd Hoffmann
2010-04-05 16:33 ` [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes Paul Brook
2010-04-06 3:24 ` Amit Shah [this message]
2010-04-06 9:34 ` Paul Brook
2010-04-06 9:58 ` Amit Shah
2010-04-06 10:21 ` Gerd Hoffmann
2010-04-06 11:05 ` Amit Shah
2010-04-06 11:16 ` Gerd Hoffmann
2010-04-06 13:30 ` Jamie Lokier
2010-04-06 7:40 ` [Qemu-devel] " Gerd Hoffmann
2010-04-06 7:54 ` Amit Shah
2010-04-06 7:36 ` [Qemu-devel] Re: [PATCH 0/5] chardev, virtio-console: flow control, error handling Gerd Hoffmann
2010-04-06 7:52 ` Amit Shah
2010-04-06 8:17 ` Gerd Hoffmann
2010-04-06 8:28 ` Amit Shah
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