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List:       kernel-janitors
Subject:    [PATCH] drivers/usb/host: Use an IS_ERR test rather than a NULL test
From:       Julien Brunel <brunel () diku ! dk>
Date:       2008-09-24 15:57:19
Message-ID: 200809241800.36320.brunel () diku ! dk
[Download RAW message or body]

In case of error, the function isp1760_register returns an ERR
pointer, but never returns a NULL pointer. So after a call to this
function, a NULL test should be replaced by an IS_ERR test. Moreover,
we have noticed that:
(1) the result of isp1760_register is assigned through the function
pci_set_drvdata without an error test,
(2) if the call to isp1760_register fails, the current function
(isp1761_pci_probe) returns 0, and if it succeeds, it returns -ENOMEM,
which seems odd.

Thus, we suggest to move the test before the call to pci_set_drvdata
to correct (1), and to turn it into a non IS_ERR test to correct (2).

The semantic match that finds this problem is as follows: 
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@bad_null_test@
expression x,E;
statement S1, S2;
@@
x =  isp1760_register(...)
... when != x = E
* if (x == NULL)
S1 else S2
// </smpl>

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

---
 drivers/usb/host/isp1760-if.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff -u -p a/drivers/usb/host/isp1760-if.c b/drivers/usb/host/isp1760-if.c
--- a/drivers/usb/host/isp1760-if.c
+++ b/drivers/usb/host/isp1760-if.c
@@ -232,9 +232,10 @@ static int __devinit isp1761_pci_probe(s
 	hcd = isp1760_register(pci_mem_phy0, length, dev->irq,
 		IRQF_SHARED | IRQF_DISABLED, &dev->dev, dev_name(&dev->dev),
 		devflags);
-	pci_set_drvdata(dev, hcd);
-	if (!hcd)
+	if (!IS_ERR(hcd)) {
+		pci_set_drvdata(dev, hcd);
 		return 0;
+	}
 clean:
 	status = -ENODEV;
 	iounmap(iobase);
--
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