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[PATCH v2 09/11] [v3] infiniband: shut up a maybe-uninitialized warning

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Some configurations produce this harmless warning when built with
gcc -Wmaybe-uninitialized:

infiniband/core/cma.c: In function 'cma_get_net_dev':
infiniband/core/cma.c:1242:12: warning: 'src_addr_storage.sin_addr.s_addr' may be used uninitialized in this function [-Wmaybe-uninitialized]

I previously reported this for the powerpc64 defconfig, but have now
reproduced the same thing for x86 as well, using gcc-5 or higher.

The code looks correct to me, and this change just rearranges it
by making sure we alway initialize the entire address structure
to make the warning disappear. My first approach added an
initialization at the time of the declaration, which Doug commented
may be too costly, so I hope this version doesn't add overhead.

Link: http://arm-soc.lixom.net/buildlogs/mainline/v4.7-rc6/buildall.powerpc.ppc64_defconfig.log.passed
Link: https://patchwork.kernel.org/patch/9212825/
Acked-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
This is marked v2 as the rest of the series but is actually version
three of the patch as I had to do some other changes already.

v3: remove accidental leftover change of the original patch

 drivers/infiniband/core/cma.c | 54 ++++++++++++++++++++++---------------------
 1 file changed, 28 insertions(+), 26 deletions(-)

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 36bf50e..89a6b05 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1094,47 +1094,47 @@ static void cma_save_ib_info(struct sockaddr *src_addr,
 	}
 }
 
-static void cma_save_ip4_info(struct sockaddr *src_addr,
-			      struct sockaddr *dst_addr,
+static void cma_save_ip4_info(struct sockaddr_in *src_addr,
+			      struct sockaddr_in *dst_addr,
 			      struct cma_hdr *hdr,
 			      __be16 local_port)
 {
-	struct sockaddr_in *ip4;
-
 	if (src_addr) {
-		ip4 = (struct sockaddr_in *)src_addr;
-		ip4->sin_family = AF_INET;
-		ip4->sin_addr.s_addr = hdr->dst_addr.ip4.addr;
-		ip4->sin_port = local_port;
+		*src_addr = (struct sockaddr_in) {
+			.sin_family = AF_INET,
+			.sin_addr.s_addr = hdr->dst_addr.ip4.addr,
+			.sin_port = local_port,
+		};
 	}
 
 	if (dst_addr) {
-		ip4 = (struct sockaddr_in *)dst_addr;
-		ip4->sin_family = AF_INET;
-		ip4->sin_addr.s_addr = hdr->src_addr.ip4.addr;
-		ip4->sin_port = hdr->port;
+		*dst_addr = (struct sockaddr_in) {
+			.sin_family = AF_INET,
+			.sin_addr.s_addr = hdr->src_addr.ip4.addr,
+			.sin_port = hdr->port,
+		};
 	}
 }
 
-static void cma_save_ip6_info(struct sockaddr *src_addr,
-			      struct sockaddr *dst_addr,
+static void cma_save_ip6_info(struct sockaddr_in6 *src_addr,
+			      struct sockaddr_in6 *dst_addr,
 			      struct cma_hdr *hdr,
 			      __be16 local_port)
 {
-	struct sockaddr_in6 *ip6;
-
 	if (src_addr) {
-		ip6 = (struct sockaddr_in6 *)src_addr;
-		ip6->sin6_family = AF_INET6;
-		ip6->sin6_addr = hdr->dst_addr.ip6;
-		ip6->sin6_port = local_port;
+		*src_addr = (struct sockaddr_in6) {
+			.sin6_family = AF_INET6,
+			.sin6_addr = hdr->dst_addr.ip6,
+			.sin6_port = local_port,
+		};
 	}
 
 	if (dst_addr) {
-		ip6 = (struct sockaddr_in6 *)dst_addr;
-		ip6->sin6_family = AF_INET6;
-		ip6->sin6_addr = hdr->src_addr.ip6;
-		ip6->sin6_port = hdr->port;
+		*dst_addr = (struct sockaddr_in6) {
+			.sin6_family = AF_INET6,
+			.sin6_addr = hdr->src_addr.ip6,
+			.sin6_port = hdr->port,
+		};
 	}
 }
 
@@ -1159,10 +1159,12 @@ static int cma_save_ip_info(struct sockaddr *src_addr,
 
 	switch (cma_get_ip_ver(hdr)) {
 	case 4:
-		cma_save_ip4_info(src_addr, dst_addr, hdr, port);
+		cma_save_ip4_info((struct sockaddr_in *)src_addr,
+				  (struct sockaddr_in *)dst_addr, hdr, port);
 		break;
 	case 6:
-		cma_save_ip6_info(src_addr, dst_addr, hdr, port);
+		cma_save_ip6_info((struct sockaddr_in6 *)src_addr,
+				  (struct sockaddr_in6 *)dst_addr, hdr, port);
 		break;
 	default:
 		return -EAFNOSUPPORT;
-- 
2.9.0

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[PATCH v2 00/11] getting back -Wmaybe-uninitialized Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 01/11] Kbuild: enable -Wmaybe-uninitialized warning for "make W=1" Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 06/11] [media] dib0700: fix nec repeat handling Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 10/11] pcmcia: fix return value of soc_pcmcia_regulator_set Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 07/11] [media] rc: print correct variable for z8f0811 Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 08/11] crypto: aesni: shut up -Wmaybe-uninitialized warning Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 02/11] NFSv4.1: work around -Wmaybe-uninitialized warning Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 11/11] Kbuild: enable -Wmaybe-uninitialized warnings by default Arnd Bergmann <arnd@arndb.de> - 2016-11-10 17:50 +0100
  [PATCH v2 09/11] [v3] infiniband: shut up a maybe-uninitialized warning Arnd Bergmann <arnd@arndb.de> - 2016-11-10 18:00 +0100
  [PATCH v2 03/11] x86: apm: avoid uninitialized data Arnd Bergmann <arnd@arndb.de> - 2016-11-10 18:00 +0100
  Re: [PATCH v2 00/11] getting back -Wmaybe-uninitialized Linus Torvalds <torvalds@linux-foundation.org> - 2016-11-11 18:20 +0100
    Re: [PATCH v2 00/11] getting back -Wmaybe-uninitialized Arnd Bergmann <arnd@arndb.de> - 2016-11-11 21:00 +0100

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