linux-kernel - [PATCH 12/13] fs/cifs: Remove redundant test

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Date:	Sun, 21 Dec 2008 16:41:57 +0100 (CET)
From:	Julia Lawall <julia@...u.dk>
To:	sfrench@...ba.org, linux-cifs-client@...ts.samba.org,
	samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH 12/13] fs/cifs: Remove redundant test

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

In fs/cifs/cifssmb.c, pLockData is tested for being NULL at the beginning
of the function, and not reassigned subsequently.

In fs/xfs/xfs_trans_buf.c, bp is tested for being NULL just a few lines
above.

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@...u.dk>

---
 fs/cifs/cifssmb.c                   |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 824df14..552642a 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1871,10 +1871,6 @@ CIFSSMBPosixLock(const int xid, struct cifsTconInfo *tcon,
 			rc = -EIO;      /* bad smb */
 			goto plk_err_exit;
 		}
-		if (pLockData == NULL) {
-			rc = -EINVAL;
-			goto plk_err_exit;
-		}
 		data_offset = le16_to_cpu(pSMBr->t2.DataOffset);
 		data_count  = le16_to_cpu(pSMBr->t2.DataCount);
 		if (data_count < sizeof(struct cifs_posix_lock)) {
--
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