Re: How to fix CHECK warning: testing a 'safe expression' ?

[Murali Karicheri]

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@xxxxxx>
> > 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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