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From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: Amit Shah <amit.shah@redhat.com>,
	Gerd Hoffmann <kraxel@redhat.com>,
	Juan Quintela <quintela@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v8 7/7] virtio-console: Enable port throttling when chardev is slow to consume data
Date: Wed, 1 Dec 2010 11:30:58 +0000	[thread overview]
Message-ID: <201012011130.58630.paul@codesourcery.com> (raw)
In-Reply-To: <90e8c0b7db1086c38283f684a159a892b4a66228.1291196789.git.amit.shah@redhat.com>

>  /* Callback function that's called when the guest sends us data */
>  static void flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t
> len) {
>      VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
> +    int ret;
> 
> -    qemu_chr_write(vcon->chr, buf, len);
> +    ret = qemu_chr_write(vcon->chr, buf, len);
> +    if (ret == -EAGAIN) {
> +        virtio_serial_throttle_port(port, true);
> +    }
>  }

This looks wrong. It will loose data in the case of a partial write
(i.e. ret < len)

Paul

  reply	other threads:[~2010-12-01 11:31 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-01  9:54 [Qemu-devel] [PATCH v8 0/7] char: non-blocking writes, virtio-console flow control Amit Shah
2010-12-01  9:54 ` [Qemu-devel] [PATCH v8 1/7] virtio-console: Factor out common init between console and generic ports Amit Shah
2010-12-01  9:54 ` [Qemu-devel] [PATCH v8 2/7] char: Add a QemuChrHandlers struct to initialise chardev handlers Amit Shah
2010-12-01  9:54 ` [Qemu-devel] [PATCH v8 3/7] char: Introduce char_set/remove_fd_handlers() Amit Shah
2010-12-01  9:54 ` [Qemu-devel] [PATCH v8 4/7] char: Add framework for a 'write unblocked' callback Amit Shah
2010-12-01  9:54 ` [Qemu-devel] [PATCH v8 5/7] char: Update send_all() to handle nonblocking chardev write requests Amit Shah
2010-12-01  9:54 ` [Qemu-devel] [PATCH v8 6/7] char: Equip the unix/tcp backend to handle nonblocking writes Amit Shah
2010-12-01  9:54 ` [Qemu-devel] [PATCH v8 7/7] virtio-console: Enable port throttling when chardev is slow to consume data Amit Shah
2010-12-01 11:30   ` Paul Brook [this message]
2010-12-01 11:48     ` Amit Shah
2010-12-01 11:59       ` Paul Brook
2010-12-01 12:12         ` Amit Shah
2010-12-01 13:08           ` Paul Brook
2010-12-02  9:21             ` Amit Shah
2010-12-02 17:31               ` Paul Brook
2010-12-06  6:55                 ` Amit Shah
2010-12-06  9:35                   ` Paul Brook
2010-12-06 10:11                     ` Amit Shah
2010-12-06 13:23                       ` Paul Brook
2010-12-07  7:11                         ` Amit Shah
2010-12-08 12:56                           ` Paul Brook
2010-12-08 14:25                             ` Amit Shah
2010-12-08 16:54                               ` Paul Brook

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