| Message ID | 1595761112-11003-5-git-send-email-Julia.Lawall@inria.fr (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | drop unnecessary list_empty | expand |
From: Julia Lawall <Julia.Lawall@inria.fr> Date: Sun, 26 Jul 2020 12:58:29 +0200 > 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/) ... > Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr> Saeed, please pick this up. Thank you.
On Mon, 2020-07-27 at 10:10 -0700, David Miller wrote: > From: Julia Lawall <Julia.Lawall@inria.fr> > Date: Sun, 26 Jul 2020 12:58:29 +0200 > > > 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/) > ... > > Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr> > > Saeed, please pick this up. > > Thank you. Applied to net-next-mlx5. Thanks !
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_matcher.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_matcher.c index 31abcbb..23a1172 100644 --- 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 mlx5dr_matcher *matcher) 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) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c index cd708dc..6ec5106 100644 --- 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(struct mlx5dr_ste *ste, { 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,
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> --- 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(-)