[PATCH nf-next v2 1/1] netfilter: nf_tables: Refine the codes to eliminate useless condition checks in nf_tables_api.c

[PATCH nf-next v2 1/1] netfilter: nf_tables: Refine the codes to eliminate useless condition checks in nf_tables_api.c

[fgao]

From: Gao Feng <fgao@ikuai8.com>

The return value of nf_tables_table_lookup is valid pointer or one
pointer error. There are two cases totally.
case1: IS_ERR(table) is true, it would return the error or reset the
table as NULL, it is unnecessary to perform the latter check
"table != NULL".
case2: IS_ERR(obj) is false, the table is one valid pointer. It is also
unnecessary to perform that check.
The nf_tables_newset and nf_tables_newobj have same logic codes.

In summary, we could move the block of condition check "table != NULL"
in the else block to eliminate the original condition checks.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
---
 v2: Remove the "table = NULL" assignment, per Pablo
 v1: Initial version

 net/netfilter/nf_tables_api.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a019a87..6e07c21 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -696,10 +696,7 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 	if (IS_ERR(table)) {
 		if (PTR_ERR(table) != -ENOENT)
 			return PTR_ERR(table);
-		table = NULL;
-	}
-
-	if (table != NULL) {
+	} else {
 		if (nlh->nlmsg_flags & NLM_F_EXCL)
 			return -EEXIST;
 		if (nlh->nlmsg_flags & NLM_F_REPLACE)
@@ -2963,10 +2960,7 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
 	if (IS_ERR(set)) {
 		if (PTR_ERR(set) != -ENOENT)
 			return PTR_ERR(set);
-		set = NULL;
-	}
-
-	if (set != NULL) {
+	} else {
 		if (nlh->nlmsg_flags & NLM_F_EXCL)
 			return -EEXIST;
 		if (nlh->nlmsg_flags & NLM_F_REPLACE)
@@ -4153,10 +4147,7 @@ static int nf_tables_newobj(struct net *net, struct sock *nlsk,
 		if (err != -ENOENT)
 			return err;
 
-		obj = NULL;
-	}
-
-	if (obj != NULL) {
+	} else {
 		if (nlh->nlmsg_flags & NLM_F_EXCL)
 			return -EEXIST;
 
-- 
1.9.1

Re: [PATCH nf-next v2 1/1] netfilter: nf_tables: Refine the codes to eliminate useless condition checks in nf_tables_api.c

[Pablo Neira Ayuso]

On Mon, Jan 16, 2017 at 10:02:57PM +0800, fgao@ikuai8.com wrote:
> From: Gao Feng <fgao@ikuai8.com>
> 
> The return value of nf_tables_table_lookup is valid pointer or one
> pointer error. There are two cases totally.
> case1: IS_ERR(table) is true, it would return the error or reset the
> table as NULL, it is unnecessary to perform the latter check
> "table != NULL".
> case2: IS_ERR(obj) is false, the table is one valid pointer. It is also
> unnecessary to perform that check.
> The nf_tables_newset and nf_tables_newobj have same logic codes.
> 
> In summary, we could move the block of condition check "table != NULL"
> in the else block to eliminate the original condition checks.

Applied, thanks feng.