| Message ID | 1595761112-11003-8-git-send-email-Julia.Lawall@inria.fr (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 18c25b4019caa94deee67e839aea6b7b626e70d5 |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | drop unnecessary list_empty | expand |
Julia Lawall <Julia.Lawall@inria.fr> wrote: > 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> > Signed-off-by: Kalle Valo <kvalo@codeaurora.org> Patch applied to ath-next branch of ath.git, thanks. 18c25b4019ca ath: drop unnecessary list_empty
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;
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(-)