Patchwork [7/13] drivers/net/wan: Remove redundant test

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Submitter Julia Lawall
Date Dec. 21, 2008, 3:39 p.m.
Message ID <Pine.LNX.4.64.0812211638550.9555@pc-004.diku.dk>
Download mbox | patch
Permalink /patch/15155/
State Accepted
Delegated to: David Miller
Headers show

Comments

Julia Lawall - Dec. 21, 2008, 3:39 p.m.
From: Julia Lawall <julia@diku.dk>

arg is checked not to be NULL a few lines before.

A simplified version of the semantic patch that makes this change is as
follows: (http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@r exists@
local idexpression x;
expression E;
position p1,p2;
@@

if (x@p1 == NULL || ...) { ... when forall
   return ...; }
... when != \(x=E\|x--\|x++\|--x\|++x\|x-=E\|x+=E\|x|=E\|x&=E\|&x\)
(
x@p2 == NULL
|
x@p2 != NULL
)

// another path to the test that is not through p1?
@s exists@
local idexpression r.x;
position r.p1,r.p2;
@@

... when != x@p1
(
x@p2 == NULL
|
x@p2 != NULL
)

@fix depends on !s@
position r.p1,r.p2;
expression x,E;
statement S1,S2;
@@

(
- if ((x@p2 != NULL) || ...)
  S1
|
- if ((x@p2 == NULL) && ...) S1
|
- BUG_ON(x@p2 == NULL);
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 drivers/net/wan/pc300_drv.c         |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

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Krzysztof Halasa - Dec. 22, 2008, 12:18 a.m.
Julia Lawall <julia@diku.dk> writes:

> arg is checked not to be NULL a few lines before.
>
> A simplified version of the semantic patch that makes this change is as
> follows: (http://www.emn.fr/x-info/coccinelle/)

> ---
>  drivers/net/wan/pc300_drv.c         |    5 ++---

Impressive. Thanks.
David Miller - Dec. 26, 2008, 2:04 a.m.
From: Julia Lawall <julia@diku.dk>
Date: Sun, 21 Dec 2008 16:39:15 +0100 (CET)

> arg is checked not to be NULL a few lines before.

Applied.
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Patch

diff --git a/drivers/net/wan/pc300_drv.c b/drivers/net/wan/pc300_drv.c
index d67957a..c23fde0 100644
--- a/drivers/net/wan/pc300_drv.c
+++ b/drivers/net/wan/pc300_drv.c
@@ -2718,9 +2718,8 @@  static int cpc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 					}
 					pc300patrntst.num_errors =
 						falc_pattern_test_error(card, ch);
-					if (!arg
-					    || copy_to_user(arg, &pc300patrntst,
-							    sizeof (pc300patterntst_t)))
+					if (copy_to_user(arg, &pc300patrntst,
+							 sizeof(pc300patterntst_t)))
 							return -EINVAL;
 				} else {
 					falc_pattern_test(card, ch, pc300patrntst.patrntst_on);