On Tue, Jul 13, 2021 at 09:49:09AM +0300, Eli Britstein wrote: > In rte_pktmbuf_mtod_offset macro, there is a casting from char * to type > 't', which may cause cast-align warning when using gcc flags > '-Werror -Wcast-align': > > .../include/rte_mbuf_core.h:723:3: error: cast increases required alignment > of target type [-Werror=cast-align] > 723 | ((t)((char *)(m)->buf_addr + (m)->data_off + (o))) > | ^ > > As the code assumes correct alignment, add first a (void *) casting, to > avoid the warning. > > Fixes: af75078fece3 ("first public release") > Cc: sta...@dpdk.org > > Signed-off-by: Eli Britstein <el...@nvidia.com>
My initial thinking was that it's the problem of the application: if -Werror=cast-align is used, it is up to the application to cast the return value of rte_pktmbuf_mtod_offset() to (void *) before casting it to the network type. But, if I understand correctly, the problem is not about the application code itself, but about inlined code in the header files of dpdk (i.e. compiling an empty C file that just includes the dpdk headers with -Werror=cast-align). Is it correct? If yes I think it should be highlighted in the commit log. Out of curiosity, how did you find the errors? I mean, is it possible that some casts are missing some other headers, or is this patchset exhaustive? Thanks, Olivier > --- > lib/mbuf/rte_mbuf_core.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/mbuf/rte_mbuf_core.h b/lib/mbuf/rte_mbuf_core.h > index bb38d7f581..dabdeee604 100644 > --- a/lib/mbuf/rte_mbuf_core.h > +++ b/lib/mbuf/rte_mbuf_core.h > @@ -720,7 +720,7 @@ struct rte_mbuf_ext_shared_info { > * The type to cast the result into. > */ > #define rte_pktmbuf_mtod_offset(m, t, o) \ > - ((t)((char *)(m)->buf_addr + (m)->data_off + (o))) > + ((t)(void *)((char *)(m)->buf_addr + (m)->data_off + (o))) > > /** > * A macro that points to the start of the data in the mbuf. > -- > 2.28.0.2311.g225365fb51 >