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SubjectRe: How to fix CHECK warning: testing a 'safe expression' ?
On 12/17/2014 05:35 PM, Murali Karicheri wrote:
> On 12/17/2014 01:49 PM, Bjorn Helgaas wrote:
>> [+cc Christopher, linux-kernel (this doesn't sound like a PCI-specific
>> question)]
>>
>> On Wed, Dec 17, 2014 at 9:18 AM, Murali Karicheri<m-karicheri2@ti.com>
>> wrote:
>>> I am trying to address CHECK warnings in my driver and wondering how to
>>> resolve 'warning: testing a 'safe expression' which appears when using
>>> IS_ERR_OR_NULL(foo)
>>>
>>> where foo is defined as
>>>
>>> struct foo_type *foo;
>>>
>>> The foo get assigned only NULL or ERR_PTR(error code). So I believe the
>>> usage is correct. But then how do I make the CHECK happy of its usage?
>>>
>>> I have tried a grep to check on the current usage of IS_ERR_OR_NULL()
>>> and
>>> found 276 of them causes this warning in the v3.18 version of the kernel
>>> that I am using
>>>
>>> $ grep -r "warning: testing a 'safe expression" * | wc -l
>>> 276
>>>
>>> Can someone help me undestand what this means and how to fix the same?
>>>
>>> I run folling for CHECK
>>>
>>> make C=2 CF="-D__CHECK_ENDIAN__" CHECK=sparse
>>
>> If you can share your actual code or point to it in the tree, you
>> might get more specific help.
>>
>> Bjorn
>
> For example I get
>
> CHECK drivers/pci/host/pci-keystone.c
> include/linux/err.h:40:16: warning: testing a 'safe expression'
>
> Actually it is for IS_ERR_OR_NULL() call in the file which is the only
> one call in the file.
>
Here is the code snippet for your convenience

struct device *dev = &pdev->dev;
struct keystone_pcie *ks_pcie;
struct pcie_port *pp;
struct resource *res;
void __iomem *reg_p;
struct phy *phy;
int ret = 0;

ks_pcie = devm_kzalloc(&pdev->dev, sizeof(*ks_pcie),
GFP_KERNEL);
if (!ks_pcie) {
dev_err(dev, "no memory for keystone pcie\n");
return -ENOMEM;
}
pp = &ks_pcie->pp;

/* initialize SerDes Phy if present */
phy = devm_phy_get(dev, "pcie-phy");
===> if (!IS_ERR_OR_NULL(phy)) {
ret = phy_init(phy);
if (ret < 0)
return ret;
}



--
Murali Karicheri
Linux Kernel, Texas Instruments


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