On Tue, Jan 29, 2019 at 6:24 PM Vladimir Sementsov-Ogievskiy
<vsement...@virtuozzo.com> wrote:
> 29.01.2019 6:31, Stefan Hajnoczi wrote:
> > On Fri, Jan 25, 2019 at 07:46:01PM +0300, Vladimir Sementsov-Ogievskiy
> > wrote:
> Hmm. In this case we definitely will have tiny extra memory usage, but we
> gain beautiful
> readability.
>
> So, like this:
>
> diff --git a/include/qemu/iov.h b/include/qemu/iov.h
> index 5f433c7768..53de1b38bb 100644
> --- a/include/qemu/iov.h
> +++ b/include/qemu/iov.h
> @@ -134,9 +134,31 @@ typedef struct QEMUIOVector {
> struct iovec *iov;
> int niov;
> int nalloc;
> - size_t size;
> + union {
> + struct {
> + void *__unused_iov_base;
This could be struct iovec *iov for nalloc > 0 users. Must resist hackiness! :)
> + size_t size;
> + };
> + struct iovec local_iov;
> + };
> } QEMUIOVector;
That's clever and not too hacky. Please include a comment so the
intent is clear:
/* Save space by reusing the embedded iovec's size field as the
total size field. Users with external iovecs don't use the embedded
iovec so this is safe. */
Stefan
