From: Julia Lawall <Julia.Lawall@inria.fr>
Date: Sun, 26 Jul 2020 12:58:29 +0200
Subject: net/mlx5: drop unnecessary list_empty
Patch-mainline: v5.9-rc1
Git-commit: 22f9d2f4ee810e6442185ba7ecab37e24de1b413
References: jsc#SLE-15172

list_for_each_entry is able to handle an empty list.
The only effect of avoiding the loop is not initializing the
index variable.
Drop list_empty tests in cases where these variables are not
used.

Note that list_for_each_entry is defined in terms of list_first_entry,
which indicates that it should not be used on an empty list.  But in
list_for_each_entry, the element obtained by list_first_entry is not
really accessed, only the address of its list_head field is compared
to the address of the list head, so the list_first_entry is safe.

The semantic patch that makes this change is as follows (with another
variant for the no brace case): (http://coccinelle.lip6.fr/)

<smpl>
@@
expression x,e;
iterator name list_for_each_entry;
statement S;
identifier i;
@@

-if (!(list_empty(x))) {
   list_for_each_entry(i,x,...) S
- }
 ... when != i
? i = e
</smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/steering/dr_matcher.c |   13 ++++------
 drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c    |    5 +--
 2 files changed, 8 insertions(+), 10 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_matcher.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_matcher.c
@@ -474,14 +474,13 @@ static int dr_matcher_add_to_tbl(struct
 	int ret;
 
 	next_matcher = NULL;
-	if (!list_empty(&tbl->matcher_list))
-		list_for_each_entry(tmp_matcher, &tbl->matcher_list, matcher_list) {
-			if (tmp_matcher->prio >= matcher->prio) {
-				next_matcher = tmp_matcher;
-				break;
-			}
-			first = false;
+	list_for_each_entry(tmp_matcher, &tbl->matcher_list, matcher_list) {
+		if (tmp_matcher->prio >= matcher->prio) {
+			next_matcher = tmp_matcher;
+			break;
 		}
+		first = false;
+	}
 
 	prev_matcher = NULL;
 	if (next_matcher && !first)
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
@@ -574,9 +574,8 @@ void mlx5dr_rule_update_rule_member(stru
 {
 	struct mlx5dr_rule_member *rule_mem;
 
-	if (!list_empty(&ste->rule_list))
-		list_for_each_entry(rule_mem, &ste->rule_list, use_ste_list)
-			rule_mem->ste = new_ste;
+	list_for_each_entry(rule_mem, &ste->rule_list, use_ste_list)
+		rule_mem->ste = new_ste;
 }
 
 static void dr_rule_clean_rule_members(struct mlx5dr_rule *rule,