[Spice-devel] [spice PATCH v1 1/3] char-device: fix usage of free/unref on WriteBuffer

[Victor Toso]

Hi,

On Thu, Nov 12, 2015 at 05:12:26PM +0100, Fabiano Fidêncio wrote:
> On Thu, Nov 12, 2015 at 5:00 PM, Victor Toso <victortoso at redhat.com> wrote:
> > There are places were the could should definetly free the
> > SpiceCharDeviceWriteBuffer and places that it should only unref it. The
> > current use of spice_char_device_write_buffer_free was missleading.
> >
> > This patch creates the spice_char_device_write_buffer_unref and properly
> > call these two functions.
> >
> > Related: https://bugs.freedesktop.org/show_bug.cgi?id=91350
> > ---
> >  server/char_device.c | 34 ++++++++++++++++++++++------------
> >  1 file changed, 22 insertions(+), 12 deletions(-)
> >
> > diff --git a/server/char_device.c b/server/char_device.c
> > index 54357f0..ee52e90 100644
> > --- a/server/char_device.c
> > +++ b/server/char_device.c
> > @@ -81,6 +81,7 @@ enum {
> >   * destroyed during a callback */
> >  static void spice_char_device_state_ref(SpiceCharDeviceState *char_dev);
> >  static void spice_char_device_state_unref(SpiceCharDeviceState *char_dev);
> > +static void spice_char_device_write_buffer_unref(SpiceCharDeviceWriteBuffer *write_buf);
> >
> >  static void spice_char_dev_write_retry(void *opaque);
> >
> > @@ -91,10 +92,11 @@ typedef struct SpiceCharDeviceMsgToClientItem {
> >
> >  static void spice_char_device_write_buffer_free(SpiceCharDeviceWriteBuffer *buf)
> >  {
> > -    if (--buf->refs == 0) {
> > -        free(buf->buf);
> > -        free(buf);
> > -    }
> > +    if (!buf)
> > +        return;
>
> Please, keep the check explicit.

Will do!

>
> > +
> > +    free(buf->buf);
> > +    free(buf);
> >  }
> >
> >  static void write_buffers_queue_free(Ring *write_queue)
> > @@ -117,9 +119,11 @@ static void spice_char_device_write_buffer_pool_add(SpiceCharDeviceState *dev,
> >          buf->origin = WRITE_BUFFER_ORIGIN_NONE;
> >          buf->client = NULL;
> >          ring_add(&dev->write_bufs_pool, &buf->link);
> > -    } else {
> > -        --buf->refs;
> > +        return;
> >      }
> > +
> > +    /* Buffer still being used - just unref for the caller */
> > +    spice_char_device_write_buffer_unref(buf);
> >  }
> >
> >  static void spice_char_device_client_send_queue_free(SpiceCharDeviceState *dev,
> > @@ -593,6 +597,15 @@ static SpiceCharDeviceWriteBuffer *spice_char_device_write_buffer_ref(SpiceCharD
> >      return write_buf;
> >  }
> >
> > +static void spice_char_device_write_buffer_unref(SpiceCharDeviceWriteBuffer *write_buf)
> > +{
> > +    spice_assert(write_buf);
> > +
> > +    write_buf->refs--;
> > +    if (write_buf->refs == 0)
> > +        spice_char_device_write_buffer_free(write_buf);
>
> Not important, but you could keep the styling:
> if (--write_buf->refs != 0)
>     return
> spice_char_device_write_buffer_free(write_buf);

I really don't think this way is more readeable. Do you want me to
change it to keep the style of the code? (just confirming if it is
necessary or not).

>
> > +}
> > +
> >  void spice_char_device_write_buffer_add(SpiceCharDeviceState *dev,
> >                                          SpiceCharDeviceWriteBuffer *write_buf)
> >  {
> > @@ -619,8 +632,7 @@ void spice_char_device_write_buffer_release(SpiceCharDeviceState *dev,
> >      spice_assert(!ring_item_is_linked(&write_buf->link));
> >      if (!dev) {
> >          spice_printerr("no device. write buffer is freed");
> > -        free(write_buf->buf);
> > -        free(write_buf);
> > +        spice_char_device_write_buffer_free(write_buf);
> >          return;
> >      }
> >
> > @@ -727,9 +739,7 @@ void spice_char_device_state_destroy(SpiceCharDeviceState *char_dev)
> >      }
> >      write_buffers_queue_free(&char_dev->write_queue);
> >      write_buffers_queue_free(&char_dev->write_bufs_pool);
> > -    if (char_dev->cur_write_buf) {
> > -        spice_char_device_write_buffer_free(char_dev->cur_write_buf);
> > -    }
> > +    spice_char_device_write_buffer_free(char_dev->cur_write_buf);
> >
> >      while (!ring_is_empty(&char_dev->clients)) {
> >          RingItem *item = ring_get_tail(&char_dev->clients);
> > @@ -895,7 +905,7 @@ static void migrate_data_marshaller_write_buffer_free(uint8_t *data, void *opaqu
> >  {
> >      SpiceCharDeviceWriteBuffer *write_buf = (SpiceCharDeviceWriteBuffer *)opaque;
> >
> > -    spice_char_device_write_buffer_free(write_buf);
> > +    spice_char_device_write_buffer_unref(write_buf);
> >  }
> >
> >  void spice_char_device_state_migrate_data_marshall(SpiceCharDeviceState *dev,
> > --
> > 2.5.0
> >
> > _______________________________________________
> > Spice-devel mailing list
> > Spice-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/spice-devel
> 
> Looks good, ACK!

Thanks,
  toso