Il 03/09/2014 13:23, Fam Zheng ha scritto:
> Not all the iov elements are always valid.
>
> Signed-off-by: Fam Zheng <[email protected]>
> ---
> dma-helpers.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/dma-helpers.c b/dma-helpers.c
> index 499b52b..3655d88 100644
> --- a/dma-helpers.c
> +++ b/dma-helpers.c
> @@ -105,6 +105,9 @@ static void dma_bdrv_unmap(DMAAIOCB *dbs)
> int i;
>
> for (i = 0; i < dbs->iov.niov; ++i) {
> + if (!(dbs->iov.iov[i].iov_base && dbs->iov.iov[i].iov_len)) {
> + break;
> + }
> dma_memory_unmap(dbs->sg->as, dbs->iov.iov[i].iov_base,
> dbs->iov.iov[i].iov_len, dbs->dir,
> dbs->iov.iov[i].iov_len);
>
Why is this needed by this patch series? Also, the only addition to iov
is here in dma_bdrv_cb:
mem = dma_memory_map(dbs->sg->as, cur_addr, &cur_len, dbs->dir);
if (!mem)
break;
qemu_iovec_add(&dbs->iov, mem, cur_len);
so iov_base cannot be NULL.
If cur_len is zero after dma_memory_map returns, mem should be NULL too.
If cur_len is zero before dma_memory_map is invoked, address_space_map
(and thus dma_memory_map) will return NULL too. However, in this case
exiting the loop is wrong. Perhaps it's better to add an if() in
dma_bdrv_cb that checks for cur_len == 0.
Paolo
