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[net-next,6/8] ipv6: mcast: use min() to simplify the code

Message ID 20240822133908.1042240-7-lizetao1@huawei.com (mailing list archive)
State New
Headers show
Series Some modifications to optimize code readability | expand

Commit Message

Li Zetao Aug. 22, 2024, 1:39 p.m. UTC
When coping sockaddr in ip6_mc_msfget(), the time of copies
depends on the minimum value between sl_count and gf_numsrc.
Using min() here is very semantic.

Signed-off-by: Li Zetao <lizetao1@huawei.com>
---
 net/ipv6/mcast.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Simon Horman Aug. 24, 2024, 5:57 p.m. UTC | #1
On Thu, Aug 22, 2024 at 09:39:06PM +0800, Li Zetao wrote:
> When coping sockaddr in ip6_mc_msfget(), the time of copies
> depends on the minimum value between sl_count and gf_numsrc.
> Using min() here is very semantic.
> 
> Signed-off-by: Li Zetao <lizetao1@huawei.com>
> ---
>  net/ipv6/mcast.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
> index 7ba01d8cfbae..b244dbf61d5f 100644
> --- a/net/ipv6/mcast.c
> +++ b/net/ipv6/mcast.c
> @@ -586,7 +586,8 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
>  	const struct in6_addr *group;
>  	struct ipv6_mc_socklist *pmc;
>  	struct ip6_sf_socklist *psl;
> -	int i, count, copycount;
> +	unsigned int count;
> +	int i, copycount;
>  
>  	group = &((struct sockaddr_in6 *)&gsf->gf_group)->sin6_addr;
>  
> @@ -610,7 +611,7 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
>  	psl = sock_dereference(pmc->sflist, sk);
>  	count = psl ? psl->sl_count : 0;

Both count and psl->sl_count are unsigned int,
so this looks safe (and more correct than what it replaces, IMHO).

>  
> -	copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
> +	copycount = min(count, gsf->gf_numsrc);

And gsf->gf_numsrc is a __u32, so min operating on it and
count looks safe to me.

Further, the code it replaces seems to be a max() operation in
both intent and function.

Reviewed-by: Simon Horman <horms@kernel.org>

>  	gsf->gf_numsrc = count;
>  	for (i = 0; i < copycount; i++) {
>  		struct sockaddr_in6 *psin6;
> -- 
> 2.34.1
> 
>
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Patch

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 7ba01d8cfbae..b244dbf61d5f 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -586,7 +586,8 @@  int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
 	const struct in6_addr *group;
 	struct ipv6_mc_socklist *pmc;
 	struct ip6_sf_socklist *psl;
-	int i, count, copycount;
+	unsigned int count;
+	int i, copycount;
 
 	group = &((struct sockaddr_in6 *)&gsf->gf_group)->sin6_addr;
 
@@ -610,7 +611,7 @@  int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
 	psl = sock_dereference(pmc->sflist, sk);
 	count = psl ? psl->sl_count : 0;
 
-	copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
+	copycount = min(count, gsf->gf_numsrc);
 	gsf->gf_numsrc = count;
 	for (i = 0; i < copycount; i++) {
 		struct sockaddr_in6 *psin6;