[dpdk-stable] patch 'examples/multi_process: fix build on Ubuntu 20.04' has been queued to LTS release 18.11.11

[Kevin Traynor]

Hi,

FYI, your patch has been queued to LTS release 18.11.11

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 11/24/20. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable-queue

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable-queue/commit/60ea36a0a2673615056aec7f8585b7647fddf4ef

Thanks.

Kevin.

---
>From 60ea36a0a2673615056aec7f8585b7647fddf4ef Mon Sep 17 00:00:00 2001
From: Bruce Richardson <bruce.richardson at intel.com>
Date: Wed, 28 Oct 2020 16:27:01 +0000
Subject: [PATCH] examples/multi_process: fix build on Ubuntu 20.04
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

[ upstream commit 27b549c12df2ef2db6b271795b4df7b14a2d9c2c ]

Two warnings are reported by gcc 9.3.0 on Ubuntu 20.04.

When producing a printable mac address the buffer was appropriately sized
for holding the mac address exactly, but the actual snprintf included a
'\n' character at the end, which means that the snprintf technically is
getting truncated i.e. the \n would not be added due to lack of space.
This gets flagged as a problem by modern versions of gcc, e.g. on Ubuntu
20.04.

main.c:77:37: warning: ‘__builtin___snprintf_chk’ output truncated
  before the last format character [-Wformat-truncation=]
   77 |     "%02x:%02x:%02x:%02x:%02x:%02x\n",
      |                                     ^

Since the \n is getting stripped anyway, we can fix the issue by just
removing it. In the process we can switch to using the standard ethernet
address formatting function from rte_ether.h.

The other warning is about possible string truncation when getting the
RX queue name:

In file included from init.c:36:
init.c: In function ‘init’:
../shared/common.h:38:28: warning: ‘%u’ directive output may be truncated
  writing between 1 and 10 bytes into a region of size 8
  [-Wformat-truncation=]
   38 | #define MP_CLIENT_RXQ_NAME "MProc_Client_%u_RX"
      |                            ^~~~~~~~~~~~~~~~~~~~
../shared/common.h:52:35: note: in expansion of macro ‘MP_CLIENT_RXQ_NAME’
   52 |  snprintf(buffer, sizeof(buffer), MP_CLIENT_RXQ_NAME, id);
      |                                   ^~~~~~~~~~~~~~~~~~

This is a false positive, as the value of the "id" is limited to 255,
being stored in the app as a uint8_t value, removing the possibility of
the %u being replaced by anything other then 3 characters max (rather than
up to 10 as thought by the compiler). Therefore, the warning can be easily
removed by changing the type of the "id" parameter to the local function
from "unsigned" to "uint8_t" also, ensuring the compiler is aware of the
range limit.

Fixes: af75078fece3 ("first public release")

Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>
Acked-by: Radu Nicolau <radu.nicolau at intel.com>
---
 .../client_server_mp/mp_server/main.c           | 17 ++++++++++-------
 .../client_server_mp/shared/common.h            |  2 +-
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/examples/multi_process/client_server_mp/mp_server/main.c b/examples/multi_process/client_server_mp/mp_server/main.c
index 98d675910e..1a5bf534ff 100644
--- a/examples/multi_process/client_server_mp/mp_server/main.c
+++ b/examples/multi_process/client_server_mp/mp_server/main.c
@@ -60,16 +60,19 @@ static const char *
 get_printable_mac_addr(uint16_t port)
 {
-	static const char err_address[] = "00:00:00:00:00:00";
-	static char addresses[RTE_MAX_ETHPORTS][sizeof(err_address)];
+	static const struct ether_addr null_mac; /* static defaults to 0 */
+	static char err_address[32];
+	static char addresses[RTE_MAX_ETHPORTS][32];
 
-	if (unlikely(port >= RTE_MAX_ETHPORTS))
+	if (unlikely(port >= RTE_MAX_ETHPORTS)) {
+		if (err_address[0] == '\0')
+			rte_ether_format_addr(err_address,
+					sizeof(err_address), &null_mac);
 		return err_address;
+	}
 	if (unlikely(addresses[port][0]=='\0')){
 		struct ether_addr mac;
 		rte_eth_macaddr_get(port, &mac);
-		snprintf(addresses[port], sizeof(addresses[port]),
-				"%02x:%02x:%02x:%02x:%02x:%02x\n",
-				mac.addr_bytes[0], mac.addr_bytes[1], mac.addr_bytes[2],
-				mac.addr_bytes[3], mac.addr_bytes[4], mac.addr_bytes[5]);
+		rte_ether_format_addr(addresses[port],
+				sizeof(addresses[port]), &mac);
 	}
 	return addresses[port];
diff --git a/examples/multi_process/client_server_mp/shared/common.h b/examples/multi_process/client_server_mp/shared/common.h
index 6dd43fcac2..76beca0101 100644
--- a/examples/multi_process/client_server_mp/shared/common.h
+++ b/examples/multi_process/client_server_mp/shared/common.h
@@ -44,5 +44,5 @@ struct port_info {
  */
 static inline const char *
-get_rx_queue_name(unsigned id)
+get_rx_queue_name(uint8_t id)
 {
 	/* buffer for return value. Size calculated by %u being replaced
-- 
2.26.2

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2020-11-18 16:33:38.744111461 +0000
+++ 0043-examples-multi_process-fix-build-on-Ubuntu-20.04.patch	2020-11-18 16:33:37.942215070 +0000
@@ -1 +1 @@
-From 27b549c12df2ef2db6b271795b4df7b14a2d9c2c Mon Sep 17 00:00:00 2001
+From 60ea36a0a2673615056aec7f8585b7647fddf4ef Mon Sep 17 00:00:00 2001
@@ -8,0 +9,2 @@
+[ upstream commit 27b549c12df2ef2db6b271795b4df7b14a2d9c2c ]
+
@@ -50 +51,0 @@
-Cc: stable at dpdk.org
@@ -60 +61 @@
-index ec7f6b11f3..b18e12dd4b 100644
+index 98d675910e..1a5bf534ff 100644
@@ -63 +64 @@
-@@ -60,10 +60,15 @@ static const char *
+@@ -60,16 +60,19 @@ static const char *
@@ -68 +69 @@
-+	static const struct rte_ether_addr null_mac; /* static defaults to 0 */
++	static const struct ether_addr null_mac; /* static defaults to 0 */
@@ -71 +71,0 @@
- 	int ret;
@@ -81,4 +81,2 @@
- 		struct rte_ether_addr mac;
-@@ -74,8 +79,6 @@ get_printable_mac_addr(uint16_t port)
- 			return err_address;
- 		}
+ 		struct ether_addr mac;
+ 		rte_eth_macaddr_get(port, &mac);