2008-12-21 15:28:41

by Julia Lawall

Subject: [PATCH 1/13] s390: Remove redundant test

From: Julia Lawall <[email protected]>

The loop above the modified code only terminates when rc is a valid pointer.

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 <[email protected]>

---
arch/s390/kernel/debug.c | 2 +-
drivers/s390/net/qeth_core_main.c | 1 -
2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
index 3665b18..e6c141c 100644
--- a/arch/s390/kernel/debug.c
+++ b/arch/s390/kernel/debug.c
@@ -391,7 +391,7 @@ debug_info_copy(debug_info_t* in, int mode)
debug_info_free(rc);
} while (1);

- if(!rc || (mode == NO_AREAS))
+ if (mode == NO_AREAS)
goto out;

for(i = 0; i < in->nr_areas; i++){
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index bbd6788..e783644 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -2346,7 +2346,6 @@ static int qeth_init_input_buffer(struct qeth_card *card,
* the QETH_IN_BUF_REQUEUE_THRESHOLD we should never run out off
* buffers
*/
- BUG_ON(!pool_entry);

buf->pool_entry = pool_entry;
for (i = 0; i < QETH_MAX_BUFFER_ELEMENTS(card); ++i) {

2008-12-22 08:46:13

by Martin Schwidefsky

Subject: Re: [PATCH 1/13] s390: Remove redundant test

On Sun, 2008-12-21 at 16:28 +0100, Julia Lawall wrote:
> The loop above the modified code only terminates when rc is a valid pointer.
>
> A simplified version of the semantic patch that makes this change is as
> follows: (http://www.emn.fr/x-info/coccinelle/)

Purely cosmetic but simplifies the code. So yes, makes sense.
Added to the s390 patch queue. Thanks Julia.

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.