2020-07-26 11:41:03

by Julia Lawall

Subject: [PATCH 2/7] sfc: drop unnecessary list_empty

list_for_each_safe 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.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

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

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

Signed-off-by: Julia Lawall <[email protected]>

---
drivers/net/ethernet/sfc/ptp.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 393b7cb..bea4725 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -1154,17 +1154,15 @@ static void efx_ptp_drop_time_expired_events(struct efx_nic *efx)

/* Drop time-expired events */
spin_lock_bh(&ptp->evt_lock);
- if (!list_empty(&ptp->evt_list)) {
- list_for_each_safe(cursor, next, &ptp->evt_list) {
- struct efx_ptp_event_rx *evt;
-
- evt = list_entry(cursor, struct efx_ptp_event_rx,
- link);
- if (time_after(jiffies, evt->expiry)) {
- list_move(&evt->link, &ptp->evt_free_list);
- netif_warn(efx, hw, efx->net_dev,
- "PTP rx event dropped\n");
- }
+ list_for_each_safe(cursor, next, &ptp->evt_list) {
+ struct efx_ptp_event_rx *evt;
+
+ evt = list_entry(cursor, struct efx_ptp_event_rx,
+ link);
+ if (time_after(jiffies, evt->expiry)) {
+ list_move(&evt->link, &ptp->evt_free_list);
+ netif_warn(efx, hw, efx->net_dev,
+ "PTP rx event dropped\n");
}
}
spin_unlock_bh(&ptp->evt_lock);

2020-07-27 12:15:43

by Edward Cree

Subject: Re: [PATCH 2/7] sfc: drop unnecessary list_empty

On 26/07/2020 11:58, Julia Lawall wrote:
> list_for_each_safe 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.
Sure, why not.
Acked-by: Edward Cree <[email protected]>

2020-07-27 18:55:55

by David Miller

Subject: Re: [PATCH 2/7] sfc: drop unnecessary list_empty

From: Julia Lawall <[email protected]>
Date: Sun, 26 Jul 2020 12:58:27 +0200

> list_for_each_safe 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.
>
> The semantic patch that makes this change is as follows:
> (http://coccinelle.lip6.fr/)
...
> Signed-off-by: Julia Lawall <[email protected]>

Applied to net-next.