[PATCH] gss_krb5: use lcm from kernel lib

[PATCH] gss_krb5: use lcm from kernel lib

[Luis Henriques]

Replace hardcoded lowest common multiple algorithm by the lcm()
function in kernel lib.

Signed-off-by: Luis Henriques <luis.henriques-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>
---
 net/sunrpc/auth_gss/gss_krb5_keys.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/net/sunrpc/auth_gss/gss_krb5_keys.c b/net/sunrpc/auth_gss/gss_krb5_keys.c
index 76e42e6..a16c5b6 100644
--- a/net/sunrpc/auth_gss/gss_krb5_keys.c
+++ b/net/sunrpc/auth_gss/gss_krb5_keys.c
@@ -59,6 +59,7 @@
 #include <linux/crypto.h>
 #include <linux/sunrpc/gss_krb5.h>
 #include <linux/sunrpc/xdr.h>
+#include <linux/lcm.h>
 
 #ifdef RPC_DEBUG
 # define RPCDBG_FACILITY        RPCDBG_AUTH
@@ -72,7 +73,7 @@
 static void krb5_nfold(u32 inbits, const u8 *in,
 		       u32 outbits, u8 *out)
 {
-	int a, b, c, lcm;
+	unsigned long ulcm;
 	int byte, i, msbit;
 
 	/* the code below is more readable if I make these bytes
@@ -82,17 +83,7 @@ static void krb5_nfold(u32 inbits, const u8 *in,
 	outbits >>= 3;
 
 	/* first compute lcm(n,k) */
-
-	a = outbits;
-	b = inbits;
-
-	while (b != 0) {
-		c = b;
-		b = a%b;
-		a = c;
-	}
-
-	lcm = outbits*inbits/a;
+	ulcm = lcm(inbits, outbits);
 
 	/* now do the real work */
 
@@ -101,7 +92,7 @@ static void krb5_nfold(u32 inbits, const u8 *in,
 
 	/* this will end up cycling through k lcm(k,n)/k times, which
 	   is correct */
-	for (i = lcm-1; i >= 0; i--) {
+	for (i = ulcm-1; i >= 0; i--) {
 		/* compute the msbit in k which gets added into this byte */
 		msbit = (
 			/* first, start with the msbit in the first,
-- 
1.8.3.2

Cheers,
--
Luis
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Re: [PATCH] gss_krb5: use lcm from kernel lib

[J. Bruce Fields]

On Sun, Jan 19, 2014 at 09:50:51PM +0000, Luis Henriques wrote:
> Replace hardcoded lowest common multiple algorithm by the lcm()
> function in kernel lib.

Looks OK to me.  Applying for 3.14 if Trond hasn't already picked it up.

--b.

> 
> Signed-off-by: Luis Henriques <luis.henriques-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>
> ---
>  net/sunrpc/auth_gss/gss_krb5_keys.c | 17 ++++-------------
>  1 file changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/net/sunrpc/auth_gss/gss_krb5_keys.c b/net/sunrpc/auth_gss/gss_krb5_keys.c
> index 76e42e6..a16c5b6 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_keys.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_keys.c
> @@ -59,6 +59,7 @@
>  #include <linux/crypto.h>
>  #include <linux/sunrpc/gss_krb5.h>
>  #include <linux/sunrpc/xdr.h>
> +#include <linux/lcm.h>
>  
>  #ifdef RPC_DEBUG
>  # define RPCDBG_FACILITY        RPCDBG_AUTH
> @@ -72,7 +73,7 @@
>  static void krb5_nfold(u32 inbits, const u8 *in,
>  		       u32 outbits, u8 *out)
>  {
> -	int a, b, c, lcm;
> +	unsigned long ulcm;
>  	int byte, i, msbit;
>  
>  	/* the code below is more readable if I make these bytes
> @@ -82,17 +83,7 @@ static void krb5_nfold(u32 inbits, const u8 *in,
>  	outbits >>= 3;
>  
>  	/* first compute lcm(n,k) */
> -
> -	a = outbits;
> -	b = inbits;
> -
> -	while (b != 0) {
> -		c = b;
> -		b = a%b;
> -		a = c;
> -	}
> -
> -	lcm = outbits*inbits/a;
> +	ulcm = lcm(inbits, outbits);
>  
>  	/* now do the real work */
>  
> @@ -101,7 +92,7 @@ static void krb5_nfold(u32 inbits, const u8 *in,
>  
>  	/* this will end up cycling through k lcm(k,n)/k times, which
>  	   is correct */
> -	for (i = lcm-1; i >= 0; i--) {
> +	for (i = ulcm-1; i >= 0; i--) {
>  		/* compute the msbit in k which gets added into this byte */
>  		msbit = (
>  			/* first, start with the msbit in the first,
> -- 
> 1.8.3.2
> 
> Cheers,
> --
> Luis
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