linux-kernel - [PATCH 4/5] drivers/net: Drop unnecessary NULL test

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Message-ID: <Pine.LNX.4.64.0907122205060.22658@ask.diku.dk>
Date:	Sun, 12 Jul 2009 22:05:33 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	yi.zhu@...el.com, jketreno@...ux.intel.com,
	reinette.chatre@...el.com, linux-wireless@...r.kernel.org,
	ipw2100-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH 4/5] drivers/net: Drop unnecessary NULL test

From: Julia Lawall <julia@...u.dk>

The result of container_of should not be NULL.  In particular, in this case
the argument to the enclosing function has passed though INIT_WORK, which
dereferences it, implying that its container cannot be NULL.

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

// <smpl>
@@
identifier fn,work,x,fld;
type T;
expression E1,E2;
statement S;
@@

static fn(struct work_struct *work) {
  ... when != work = E1
  x = container_of(work,T,fld)
  ... when != x = E2
- if (x == NULL) S
  ...
}
// </smpl>

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

---
 drivers/net/wireless/ipw2x00/ipw2200.c         |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ipw2x00/ipw2200.c b/drivers/net/wireless/ipw2x00/ipw2200.c
index d726b3c..2dc1cdb 100644
--- a/drivers/net/wireless/ipw2x00/ipw2200.c
+++ b/drivers/net/wireless/ipw2x00/ipw2200.c
@@ -7250,9 +7250,6 @@ static void ipw_bg_qos_activate(struct work_struct *work)
 	struct ipw_priv *priv =
 		container_of(work, struct ipw_priv, qos_activate);
 
-	if (priv == NULL)
-		return;
-
 	mutex_lock(&priv->mutex);
 
 	if (priv->status & STATUS_ASSOCIATED)
--
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