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From: Julia Lawall on 27 May 2010 08:40
From: Julia Lawall <julia(a)diku.dk>

At the point of the test, action cannot be NULL, as it has been dereferenced
in the code just above.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
expression E,E1;
identifier f;
statement S1,S2,S3;
@@

if ((E == NULL && ...) || ...)
{
... when != if (...) S1 else S2
when != E = E1
* E->f
... when any
}
else S3
// </smpl>

Signed-off-by: Julia Lawall <julia(a)diku.dk>

---
arch/sparc/kernel/sun4d_irq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sparc/kernel/sun4d_irq.c b/arch/sparc/kernel/sun4d_irq.c
index ab036a7..e11b461 100644
--- a/arch/sparc/kernel/sun4d_irq.c
+++ b/arch/sparc/kernel/sun4d_irq.c
@@ -183,7 +183,7 @@ void sun4d_free_irq(unsigned int irq, void *dev_id)
goto out_unlock;
}

- if (action && tmp)
+ if (tmp)
tmp->next = action->next;
else
*actionp = action->next;
--
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