From f37a2e7c747b0758fcd8390482aeeac490f688b5 Mon Sep 17 00:00:00 2001 From: Andy Green Date: Tue, 22 May 2018 09:24:22 +0800 Subject: [PATCH] net: explicit cast in L4 checksum 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") Cc: stable@dpdk.org Signed-off-by: Andy Green Acked-by: Bruce Richardson --- 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 c924aca7f1..72dc2456ab 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); -- 2.20.1