[PATCH 7/7] ath: drop unnecessary list_empty

[Julia Lawall]

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.law...@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;