diff mbox

[iproute,v2,7/7] ip/tcp_metrics: Simplify process_msg a bit

Message ID 87k2hhmp8q.fsf@frog.home
State Accepted, archived
Delegated to: stephen hemminger
Headers show

Commit Message

Jakub Sitnicki June 22, 2016, 11:34 a.m. UTC 
On Tue, Jun 21, 2016 at 06:18 PM CEST, Phil Sutter <phil@nwl.cc> wrote:
> By combining the attribute extraction and check for existence, the
> additional indentation level in the 'else' clause can be avoided.
>
> In addition to that, common actions for 'daddr' are combined since the
> function returns if neither of the branches are taken.
>
> Signed-off-by: Phil Sutter <phil@nwl.cc>
> ---
>  ip/tcp_metrics.c | 45 ++++++++++++++++++---------------------------
>  1 file changed, 18 insertions(+), 27 deletions(-)
>
> diff --git a/ip/tcp_metrics.c b/ip/tcp_metrics.c
> index f82604f458ada..899830c127bcb 100644
> --- a/ip/tcp_metrics.c
> +++ b/ip/tcp_metrics.c
> @@ -112,47 +112,38 @@ static int process_msg(const struct sockaddr_nl *who, struct nlmsghdr *n,
>  	parse_rtattr(attrs, TCP_METRICS_ATTR_MAX, (void *) ghdr + GENL_HDRLEN,
>  		     len);
>  
> -	a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
> -	if (a) {
> +	if ((a = attrs[TCP_METRICS_ATTR_ADDR_IPV4])) {

Copy the pointer inside the branch?

Same gain on indentation while keeping checkpatch happy.

I only compile-tested the patch below.

Thanks,
Jakub

Comments

Phil Sutter June 22, 2016, 12:55 p.m. UTC | #1 
On Wed, Jun 22, 2016 at 01:34:13PM +0200, Jakub Sitnicki wrote:
> On Tue, Jun 21, 2016 at 06:18 PM CEST, Phil Sutter <phil@nwl.cc> wrote:
[...]
> > -	a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
> > -	if (a) {
> > +	if ((a = attrs[TCP_METRICS_ATTR_ADDR_IPV4])) {
> 
> Copy the pointer inside the branch?
> 
> Same gain on indentation while keeping checkpatch happy.

Good point! Thanks for the patch. :)

Cheers, Phil
David Laight June 22, 2016, 1 p.m. UTC | #2 
From: Jakub Sitnicki
> Sent: 22 June 2016 12:34
...
> > -	a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
> > -	if (a) {
> > +	if ((a = attrs[TCP_METRICS_ATTR_ADDR_IPV4])) {
> 
> Copy the pointer inside the branch?
> 
> Same gain on indentation while keeping checkpatch happy.

Or as below (hacked from the mails):

	a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
	if (a) {
 		if (f.daddr.family && f.daddr.family != AF_INET)
 			return 0;
 		memcpy(&daddr.data, RTA_DATA(a), 4);
 		daddr.bytelen = 4;
 		family = AF_INET;
 		atype = TCP_METRICS_ATTR_ADDR_IPV4;
 		dlen = RTA_PAYLOAD(a);
	} else {
		a = attrs[TCP_METRICS_ATTR_ADDR_IPV6];
		if (!a)
			return 0;
		memcpy(&daddr.data, RTA_DATA(a), 16);
		daddr.bytelen = 16;
		family = AF_INET6;
		atype = TCP_METRICS_ATTR_ADDR_IPV6;
		dlen = RTA_PAYLOAD(a);
	}

	David
Phil Sutter June 22, 2016, 1:08 p.m. UTC | #3 
Hi David,

On Wed, Jun 22, 2016 at 01:00:08PM +0000, David Laight wrote:
> From: Jakub Sitnicki
> > Sent: 22 June 2016 12:34
> ...
> > > -	a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
> > > -	if (a) {
> > > +	if ((a = attrs[TCP_METRICS_ATTR_ADDR_IPV4])) {
> > 
> > Copy the pointer inside the branch?
> > 
> > Same gain on indentation while keeping checkpatch happy.
> 
> Or as below (hacked from the mails):
> 
> 	a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
> 	if (a) {
>  		if (f.daddr.family && f.daddr.family != AF_INET)
>  			return 0;
>  		memcpy(&daddr.data, RTA_DATA(a), 4);
>  		daddr.bytelen = 4;
>  		family = AF_INET;
>  		atype = TCP_METRICS_ATTR_ADDR_IPV4;
>  		dlen = RTA_PAYLOAD(a);
> 	} else {
> 		a = attrs[TCP_METRICS_ATTR_ADDR_IPV6];
> 		if (!a)
> 			return 0;
> 		memcpy(&daddr.data, RTA_DATA(a), 16);
> 		daddr.bytelen = 16;
> 		family = AF_INET6;
> 		atype = TCP_METRICS_ATTR_ADDR_IPV6;
> 		dlen = RTA_PAYLOAD(a);
> 	}

Yes, this should work as well and require less code changes overall.
Though I think it's less readable:

| if (a) {
| 	do a;
| else {
| 	if (!b)
| 		return;
| 	do b;
| }

vs.

| if (a) {
| 	do a;
| } else if (b) {
| 	do b;
| } else {
| 	return;
| }

Don't you think?

Thanks, Phil
diff mbox

Patch

diff --git a/ip/tcp_metrics.c b/ip/tcp_metrics.c
index f82604f..ac2613a 100644
--- a/ip/tcp_metrics.c
+++ b/ip/tcp_metrics.c
@@ -112,47 +112,44 @@  static int process_msg(const struct sockaddr_nl *who, struct nlmsghdr *n,
 	parse_rtattr(attrs, TCP_METRICS_ATTR_MAX, (void *) ghdr + GENL_HDRLEN,
 		     len);
 
-	a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
-	if (a) {
+	if (attrs[TCP_METRICS_ATTR_ADDR_IPV4]) {
 		if (f.daddr.family && f.daddr.family != AF_INET)
 			return 0;
+		a = attrs[TCP_METRICS_ATTR_ADDR_IPV4];
 		memcpy(&daddr.data, RTA_DATA(a), 4);
 		daddr.bytelen = 4;
 		family = AF_INET;
 		atype = TCP_METRICS_ATTR_ADDR_IPV4;
 		dlen = RTA_PAYLOAD(a);
-	} else {
-		a = attrs[TCP_METRICS_ATTR_ADDR_IPV6];
-		if (a) {
-			if (f.daddr.family && f.daddr.family != AF_INET6)
-				return 0;
-			memcpy(&daddr.data, RTA_DATA(a), 16);
-			daddr.bytelen = 16;
-			family = AF_INET6;
-			atype = TCP_METRICS_ATTR_ADDR_IPV6;
-			dlen = RTA_PAYLOAD(a);
-		} else
+	} else if (attrs[TCP_METRICS_ATTR_ADDR_IPV6]) {
+		if (f.daddr.family && f.daddr.family != AF_INET6)
 			return 0;
+		a = attrs[TCP_METRICS_ATTR_ADDR_IPV6];
+		memcpy(&daddr.data, RTA_DATA(a), 16);
+		daddr.bytelen = 16;
+		family = AF_INET6;
+		atype = TCP_METRICS_ATTR_ADDR_IPV6;
+		dlen = RTA_PAYLOAD(a);
+	} else {
+		return 0;
 	}
 
-	a = attrs[TCP_METRICS_ATTR_SADDR_IPV4];
-	if (a) {
+	if (attrs[TCP_METRICS_ATTR_SADDR_IPV4]) {
 		if (f.saddr.family && f.saddr.family != AF_INET)
 			return 0;
+		a = attrs[TCP_METRICS_ATTR_SADDR_IPV4];
 		memcpy(&saddr.data, RTA_DATA(a), 4);
 		saddr.bytelen = 4;
 		stype = TCP_METRICS_ATTR_SADDR_IPV4;
 		slen = RTA_PAYLOAD(a);
-	} else {
+	} else if (attrs[TCP_METRICS_ATTR_SADDR_IPV6]) {
+		if (f.saddr.family && f.saddr.family != AF_INET6)
+			return 0;
 		a = attrs[TCP_METRICS_ATTR_SADDR_IPV6];
-		if (a) {
-			if (f.saddr.family && f.saddr.family != AF_INET6)
-				return 0;
-			memcpy(&saddr.data, RTA_DATA(a), 16);
-			saddr.bytelen = 16;
-			stype = TCP_METRICS_ATTR_SADDR_IPV6;
-			slen = RTA_PAYLOAD(a);
-		}
+		memcpy(&saddr.data, RTA_DATA(a), 16);
+		saddr.bytelen = 16;
+		stype = TCP_METRICS_ATTR_SADDR_IPV6;
+		slen = RTA_PAYLOAD(a);
 	}
 
 	if (f.daddr.family && f.daddr.bitlen >= 0 &&