[dpdk-stable] patch 'net: explicit cast in L4 checksum' has been queued to stable release 18.02.2

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 18.02.2

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 05/25/18. So please
shout if anyone has objections.

Thanks.

Luca Boccassi

---
>From 819c4e0bdc5e6b5143e338f06019358eaf5a5e9b Mon Sep 17 00:00:00 2001
From: Andy Green <andy at warmcat.com>
Date: Tue, 22 May 2018 09:24:22 +0800
Subject: [PATCH] net: explicit cast in L4 checksum

[ upstream commit f37a2e7c747b0758fcd8390482aeeac490f688b5 ]

GCC 8.1 warned:

In function 'rte_ipv4_udptcp_cksum':
rte_byteorder.h:51:24: warning: conversion from 'long unsigned int' to
'uint32_t' {aka 'unsigned int'} may change value [-Wconversion]
 #define rte_bswap16(x) ((uint16_t) (__builtin_constant_p(x) ?  \
                        ^
rte_byteorder.h:85:29: note: in expansion of macro 'rte_bswap16'
 #define rte_be_to_cpu_16(x) rte_bswap16(x)
                             ^~~~~~~~~~~
rte_ip.h:321:11: note: in expansion of macro 'rte_be_to_cpu_16'
  l4_len = rte_be_to_cpu_16(ipv4_hdr->total_length) -
           ^~~~~~~~~~~~~~~~

Also with this one, it is a cast that always occurred
and is just being done explicitly, with no changes to
the generated code.

The warning stack is misleading, it points to the last
element in the macro that produced the lhs of the subtraction
above.  But the only "unsigned long int" in the expression is
the result of the sizeof() on the rhs, it promotes the
subtraction result to unsigned long.  So the error actually
relates to the result of the outer subtraction.

The actual error is "you are trying to put an unsigned long
into a uint32_t".  We always did so, the fix is just to inform
the compiler it is intentional with an explicit cast.

Fixes: 6006818cfb ("net: new checksum functions")

Signed-off-by: Andy Green <andy at warmcat.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>
---
 lib/librte_net/rte_ip.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h
index c924aca7f..72dc2456a 100644
--- a/lib/librte_net/rte_ip.h
+++ b/lib/librte_net/rte_ip.h
@@ -318,8 +318,8 @@ rte_ipv4_udptcp_cksum(const struct ipv4_hdr *ipv4_hdr, const void *l4_hdr)
 	uint32_t cksum;
 	uint32_t l4_len;
 
-	l4_len = rte_be_to_cpu_16(ipv4_hdr->total_length) -
-		sizeof(struct ipv4_hdr);
+	l4_len = (uint32_t)(rte_be_to_cpu_16(ipv4_hdr->total_length) -
+		sizeof(struct ipv4_hdr));
 
 	cksum = rte_raw_cksum(l4_hdr, l4_len);
 	cksum += rte_ipv4_phdr_cksum(ipv4_hdr, 0);
-- 
2.14.2