linux-kernel - [PATCH 0/7] drop unnecessary list

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Date:   Sun, 26 Jul 2020 12:58:25 +0200
From:   Julia Lawall <Julia.Lawall@...ia.fr>
To:     linux-rdma@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        linux-media@...r.kernel.org, linux-wireless@...r.kernel.org
Subject: [PATCH 0/7] drop unnecessary list_empty

The various list iterators are able to handle an empty list.
The only effect of avoiding the loop is not initializing some
index variables.
Drop list_empty tests in cases where these variables are not
used.

The semantic patch that makes these changes is as follows:
(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

@@
expression x,e;
iterator name list_for_each_entry_safe;
statement S;
identifier i,j;
@@

-if (!(list_empty(x))) {
   list_for_each_entry_safe(i,j,x,...) S
- }
 ... when != i
     when != j
(
  i = e;
|
? j = e;
)

@@
expression x,e;
iterator name list_for_each;
statement S;
identifier i;
@@

-if (!(list_empty(x))) {
   list_for_each(i,x) S
- }
 ... when != i
? i = e

@@
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;
)

// -------------------

@@
expression x,e;
statement S;
identifier i;
@@

-if (!(list_empty(x)))
   list_for_each_entry(i,x,...) S
 ... when != i
? i = e

@@
expression x,e;
statement S;
identifier i,j;
@@

-if (!(list_empty(x)))
   list_for_each_entry_safe(i,j,x,...) S
 ... when != i
     when != j
(
  i = e;
|
? j = e;
)

@@
expression x,e;
statement S;
identifier i;
@@

-if (!(list_empty(x)))
   list_for_each(i,x) S
 ... when != i
? i = e

@@
expression x,e;
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>

---

 drivers/media/pci/saa7134/saa7134-core.c                      |   14 ++---
 drivers/media/usb/cx231xx/cx231xx-core.c                      |   16 ++----
 drivers/media/usb/tm6000/tm6000-core.c                        |   24 +++-------
 drivers/net/ethernet/mellanox/mlx5/core/steering/dr_matcher.c |   13 ++---
 drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c    |    5 --
 drivers/net/ethernet/sfc/ptp.c                                |   20 +++-----
 drivers/net/wireless/ath/dfs_pattern_detector.c               |   15 ++----
 sound/soc/intel/atom/sst/sst_loader.c                         |   10 +---
 sound/soc/intel/skylake/skl-pcm.c                             |    8 +--
 sound/soc/intel/skylake/skl-topology.c                        |    5 --
 10 files changed, 53 insertions(+), 77 deletions(-)