netdev - [PATCH] ipvs: use div_s64 for signed division

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Date:   Thu, 15 Dec 2022 18:03:15 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Simon Horman <horms@...ge.net.au>, Julian Anastasov <ja@....bg>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Jiri Wiesner <jwiesner@...e.de>, netdev@...r.kernel.org,
        lvs-devel@...r.kernel.org, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ipvs: use div_s64 for signed division

From: Arnd Bergmann <arnd@...db.de>

do_div() is only well-behaved for positive numbers, and now warns
when the first argument is a an s64:

net/netfilter/ipvs/ip_vs_est.c: In function 'ip_vs_est_calc_limits':
include/asm-generic/div64.h:222:35: error: comparison of distinct pointer types lacks a cast [-Werror]
  222 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
      |                                   ^~
net/netfilter/ipvs/ip_vs_est.c:694:17: note: in expansion of macro 'do_div'
  694 |                 do_div(val, loops);

Convert to using the more appropriate div_s64(), which also
simplifies the code a bit.

Fixes: 705dd3444081 ("ipvs: use kthreads for stats estimation")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 net/netfilter/ipvs/ip_vs_est.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
index ce2a1549b304..dbc32f8cf1f9 100644
--- a/net/netfilter/ipvs/ip_vs_est.c
+++ b/net/netfilter/ipvs/ip_vs_est.c
@@ -691,15 +691,13 @@ static int ip_vs_est_calc_limits(struct netns_ipvs *ipvs, int *chain_max)
 		}
 		if (diff >= NSEC_PER_SEC)
 			continue;
-		val = diff;
-		do_div(val, loops);
+		val = div_s64(diff, loops);
 		if (!min_est || val < min_est) {
 			min_est = val;
 			/* goal: 95usec per chain */
 			val = 95 * NSEC_PER_USEC;
 			if (val >= min_est) {
-				do_div(val, min_est);
-				max = (int)val;
+				max = div_s64(val, min_est);
 			} else {
 				max = 1;
 			}
-- 
2.35.1