Re: [Xen-devel] [PATCH] xen-netback: fix type mismatch warning

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@xxxxxxxx]
> Sent: 12 October 2016 10:54
> To: Wei Liu <wei.liu2@xxxxxxxxxx>; Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>; David S. Miller
> <davem@xxxxxxxxxxxxx>; David Vrabel <david.vrabel@xxxxxxxxxx>; xen-
> devel@xxxxxxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH] xen-netback: fix type mismatch warning
> 
> Wiht the latest rework of the xen-netback driver, we get a warning
> on ARM about the types passed into min():
> 
> drivers/net/xen-netback/rx.c: In function 'xenvif_rx_next_chunk':
> include/linux/kernel.h:739:16: error: comparison of distinct pointer types
> lacks a cast [-Werror]
> 
> The reason is that XEN_PAGE_SIZE is not size_t here. There
> is no actual bug, and we can easily avoid the warning using the
> min_t() macro instead of min().
> 
> Fixes: eb1723a29b9a ("xen-netback: refactor guest rx")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

LGTM

Acked-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> ---
>  drivers/net/xen-netback/rx.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
> index 8e9ade6ccf18..aeb150258c6c 100644
> --- a/drivers/net/xen-netback/rx.c
> +++ b/drivers/net/xen-netback/rx.c
> @@ -337,9 +337,9 @@ static void xenvif_rx_next_chunk(struct
> xenvif_queue *queue,
>       frag_data += pkt->frag_offset;
>       frag_len -= pkt->frag_offset;
> 
> -     chunk_len = min(frag_len, XEN_PAGE_SIZE - offset);
> -     chunk_len = min(chunk_len,
> -                     XEN_PAGE_SIZE -
>       xen_offset_in_page(frag_data));
> +     chunk_len = min_t(size_t, frag_len, XEN_PAGE_SIZE - offset);
> +     chunk_len = min_t(size_t, chunk_len, XEN_PAGE_SIZE -
> +                                          xen_offset_in_page(frag_data));
> 
>       pkt->frag_offset += chunk_len;
> 
> --
> 2.9.0


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