| Message ID | 1270020848-15526-16-git-send-email-amit.shah@redhat.com |
|---|---|
| State | New |
| Headers | show |
> /* Callback function that's called when the guest sends us data */ > -static size_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) > +static void flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) > { > VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port); > - ssize_t ret; > > - ret = qemu_chr_write(vcon->chr, buf, len); > - > - return ret< 0 ? 0 : ret; > + qemu_chr_write(vcon->chr, buf, len); > } Ok, so we loose data in case qemu_chr_write wasn't able to write out all data? Nice opportunity to show flow control in action here ;) On failed+partial writes just put the remaining data into a buffer and throttle the port until all buffered data has been successfully written to the chardev. Incremental patch is fine to avoid the chicken-egg issue (throttling is added by patch #17). cheers, Gerd
On (Wed) Mar 31 2010 [15:53:59], Gerd Hoffmann wrote: >> /* Callback function that's called when the guest sends us data */ >> -static size_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) >> +static void flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) >> { >> VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port); >> - ssize_t ret; >> >> - ret = qemu_chr_write(vcon->chr, buf, len); >> - >> - return ret< 0 ? 0 : ret; >> + qemu_chr_write(vcon->chr, buf, len); >> } > > Ok, so we loose data in case qemu_chr_write wasn't able to write out all > data? Nice opportunity to show flow control in action here ;) > > On failed+partial writes just put the remaining data into a buffer and > throttle the port until all buffered data has been successfully written > to the chardev. > > Incremental patch is fine to avoid the chicken-egg issue (throttling is > added by patch #17). Yes, that's what I intend to do in a later patch (series). Amit
diff --git a/hw/virtio-console.c b/hw/virtio-console.c index bbbb6b8..caea11f 100644 --- a/hw/virtio-console.c +++ b/hw/virtio-console.c @@ -20,14 +20,11 @@ typedef struct VirtConsole { /* Callback function that's called when the guest sends us data */ -static size_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) +static void flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) { VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port); - ssize_t ret; - ret = qemu_chr_write(vcon->chr, buf, len); - - return ret < 0 ? 0 : ret; + qemu_chr_write(vcon->chr, buf, len); } /* Readiness of the guest to accept data on a port */ diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index 49a6baa..7ac46f5 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -336,7 +336,7 @@ static void control_out(VirtIODevice *vdev, VirtQueue *vq) copied = iov_to_buf(elem.out_sg, elem.out_num, buf, 0, len); handle_control_message(vser, buf, copied); - virtqueue_push(vq, &elem, copied); + virtqueue_push(vq, &elem, 0); } if (len) { qemu_free(buf); @@ -382,11 +382,11 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq) buf = qemu_malloc(buf_size); ret = iov_to_buf(elem.out_sg, elem.out_num, buf, 0, buf_size); - ret = port->info->have_data(port, buf, ret); + port->info->have_data(port, buf, ret); qemu_free(buf); next_buf: - virtqueue_push(vq, &elem, ret); + virtqueue_push(vq, &elem, 0); } virtio_notify(vdev, vq); } diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h index f023873..62d76a2 100644 --- a/hw/virtio-serial.h +++ b/hw/virtio-serial.h @@ -136,10 +136,10 @@ struct VirtIOSerialPortInfo { /* * Guest wrote some data to the port. This data is handed over to - * the app via this callback. The app should return the number of - * bytes it successfully consumed. + * the app via this callback. The app is supposed to consume all + * the data that is presented to it. */ - size_t (*have_data)(VirtIOSerialPort *port, const uint8_t *buf, size_t len); + void (*have_data)(VirtIOSerialPort *port, const uint8_t *buf, size_t len); }; /* Interface to the virtio-serial bus */
We cannot indicate to the guest how much data was consumed by an app for out_bufs. So we just have to assume the apps will consume all the data that are handed over to them. Fix the virtio api abuse in control_out() and handle_output(). Signed-off-by: Amit Shah <amit.shah@redhat.com> --- hw/virtio-console.c | 7 ++----- hw/virtio-serial-bus.c | 6 +++--- hw/virtio-serial.h | 6 +++--- 3 files changed, 8 insertions(+), 11 deletions(-)