[PATCH 7/7] ath: drop unnecessary list_empty
From: Julia Lawall <Julia.Lawall@inria.fr>
Date: 2020-07-26 11:40:04
Also in:
kernel-janitors, linux-wireless, lkml
Subsystem:
atheros ath generic utilities, the rest · Maintainers:
Jeff Johnson, Linus Torvalds
list_for_each_entry{_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.
Note that list_for_each_entry{_safe} 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{_safe}, 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 for the list_for_each_entry
case is as follows: (http://coccinelle.lip6.fr/)
<smpl>
@@
expression x,e;
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/wireless/ath/dfs_pattern_detector.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/drivers/net/wireless/ath/dfs_pattern_detector.c b/drivers/net/wireless/ath/dfs_pattern_detector.c
index a274eb0..0813473 100644
--- a/drivers/net/wireless/ath/dfs_pattern_detector.c
+++ b/drivers/net/wireless/ath/dfs_pattern_detector.c@@ -253,17 +253,15 @@ static void channel_detector_exit(struct dfs_pattern_detector *dpd, static void dpd_reset(struct dfs_pattern_detector *dpd) { struct channel_detector *cd; - if (!list_empty(&dpd->channel_detectors)) - list_for_each_entry(cd, &dpd->channel_detectors, head) - channel_detector_reset(dpd, cd); + list_for_each_entry(cd, &dpd->channel_detectors, head) + channel_detector_reset(dpd, cd); } static void dpd_exit(struct dfs_pattern_detector *dpd) { struct channel_detector *cd, *cd0; - if (!list_empty(&dpd->channel_detectors)) - list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head) - channel_detector_exit(dpd, cd); + list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head) + channel_detector_exit(dpd, cd); kfree(dpd); }
@@ -331,9 +329,8 @@ static bool dpd_set_domain(struct dfs_pattern_detector *dpd, return false; /* delete all channel detectors for previous DFS domain */ - if (!list_empty(&dpd->channel_detectors)) - list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head) - channel_detector_exit(dpd, cd); + list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head) + channel_detector_exit(dpd, cd); dpd->radar_spec = rt->radar_types; dpd->num_radar_types = rt->num_radar_types;