[dpdk-dev] [PATCH] mbuf: properly cast shared data

[dpdk-dev] [PATCH] mbuf: properly cast shared data

[David Marchand]

Including rte_mbuf.h in C++ triggers the following warning as C++ does not
allow implicit casting of a void *.

In file included from test.cpp:1:0:
x86_64-native-linuxapp-gcc/include/rte_mbuf.h: In function
‘rte_mbuf_ext_shared_info* rte_pktmbuf_ext_shinfo_init_helper(void*, uint16_t*,
rte_mbuf_extbuf_free_callback_t, void*)’:
x86_64-native-linuxapp-gcc/include/rte_mbuf.h:1349:9: error: invalid conversion
from ‘void*’ to ‘rte_mbuf_ext_shared_info*’ [-fpermissive]
  shinfo = RTE_PTR_ALIGN_FLOOR(RTE_PTR_SUB(buf_end,
         ^

Fixes: a53aa2b9f3be ("mbuf: support attaching external buffer")
Signed-off-by: David Marchand <david.marchand@6wind.com>
---
 lib/librte_mbuf/rte_mbuf.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 4fd9a0d..eab13c6 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1345,12 +1345,14 @@ rte_pktmbuf_ext_shinfo_init_helper(void *buf_addr, uint16_t *buf_len,
 {
 	struct rte_mbuf_ext_shared_info *shinfo;
 	void *buf_end = RTE_PTR_ADD(buf_addr, *buf_len);
+	void *addr;
 
-	shinfo = RTE_PTR_ALIGN_FLOOR(RTE_PTR_SUB(buf_end,
-				sizeof(*shinfo)), sizeof(uintptr_t));
-	if ((void *)shinfo <= buf_addr)
+	addr = RTE_PTR_ALIGN_FLOOR(RTE_PTR_SUB(buf_end, sizeof(*shinfo)),
+				   sizeof(uintptr_t));
+	if (addr <= buf_addr)
 		return NULL;
 
+	shinfo = (struct rte_mbuf_ext_shared_info *)addr;
 	shinfo->free_cb = free_cb;
 	shinfo->fcb_opaque = fcb_opaque;
 	rte_mbuf_ext_refcnt_set(shinfo, 1);
-- 
2.7.4

Re: [dpdk-dev] [PATCH] mbuf: properly cast shared data

[Thomas Monjalon]

16/05/2018 13:10, David Marchand:
> Including rte_mbuf.h in C++ triggers the following warning as C++ does not
> allow implicit casting of a void *.
> 
> In file included from test.cpp:1:0:
> x86_64-native-linuxapp-gcc/include/rte_mbuf.h: In function
> ‘rte_mbuf_ext_shared_info* rte_pktmbuf_ext_shinfo_init_helper(void*, uint16_t*,
> rte_mbuf_extbuf_free_callback_t, void*)’:
> x86_64-native-linuxapp-gcc/include/rte_mbuf.h:1349:9: error: invalid conversion
> from ‘void*’ to ‘rte_mbuf_ext_shared_info*’ [-fpermissive]
>   shinfo = RTE_PTR_ALIGN_FLOOR(RTE_PTR_SUB(buf_end,
>          ^
> 
> Fixes: a53aa2b9f3be ("mbuf: support attaching external buffer")
> Signed-off-by: David Marchand <david.marchand@6wind.com>

Applied, thanks