Re: [PATCH 2/5] misc: pci_endpoint_test: Fix the return value of IOCTL

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Fri, Aug 19, 2022 at 05:25:01PM +0200, Greg KH wrote:
> On Fri, Aug 19, 2022 at 08:20:15PM +0530, Manivannan Sadhasivam wrote:
> > IOCTLs are supposed to return 0 for success and negative error codes for
> > failure. Currently, this driver is returning 0 for failure and 1 for
> > success, that's not correct. Hence, fix it!
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> >  drivers/misc/pci_endpoint_test.c | 163 ++++++++++++++-----------------
> >  1 file changed, 76 insertions(+), 87 deletions(-)
> > 
> > diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> > index db0458039d7d..bbf903c5a5bd 100644
> > --- a/drivers/misc/pci_endpoint_test.c
> > +++ b/drivers/misc/pci_endpoint_test.c
> > @@ -174,13 +174,12 @@ static void pci_endpoint_test_free_irq_vectors(struct pci_endpoint_test *test)
> >  	test->irq_type = IRQ_TYPE_UNDEFINED;
> >  }
> >  
> > -static bool pci_endpoint_test_alloc_irq_vectors(struct pci_endpoint_test *test,
> > +static int pci_endpoint_test_alloc_irq_vectors(struct pci_endpoint_test *test,
> >  						int type)
> >  {
> > -	int irq = -1;
> > +	int irq = -EINVAL;
> >  	struct pci_dev *pdev = test->pdev;
> >  	struct device *dev = &pdev->dev;
> > -	bool res = true;
> >  
> >  	switch (type) {
> >  	case IRQ_TYPE_LEGACY:
> > @@ -202,15 +201,16 @@ static bool pci_endpoint_test_alloc_irq_vectors(struct pci_endpoint_test *test,
> >  		dev_err(dev, "Invalid IRQ type selected\n");
> >  	}
> >  
> > +	test->irq_type = type;
> > +
> >  	if (irq < 0) {
> > -		irq = 0;
> > -		res = false;
> > +		test->num_irqs = 0;
> > +		return irq;
> 
> Why are you setting the type if there is an error?
> 

This was the original behaviour, so I kept it as it is. If it needs to be
changed, then it should be done in a separate patch I believe.

> 
> >  	}
> >  
> > -	test->irq_type = type;
> >  	test->num_irqs = irq;
> >  
> > -	return res;
> > +	return 0;
> >  }
> >  
> >  static void pci_endpoint_test_release_irq(struct pci_endpoint_test *test)
> > @@ -225,7 +225,7 @@ static void pci_endpoint_test_release_irq(struct pci_endpoint_test *test)
> >  	test->num_irqs = 0;
> >  }
> >  
> > -static bool pci_endpoint_test_request_irq(struct pci_endpoint_test *test)
> > +static int pci_endpoint_test_request_irq(struct pci_endpoint_test *test)
> >  {
> >  	int i;
> >  	int err;
> > @@ -240,7 +240,7 @@ static bool pci_endpoint_test_request_irq(struct pci_endpoint_test *test)
> >  			goto fail;
> >  	}
> >  
> > -	return true;
> > +	return 0;
> >  
> >  fail:
> >  	switch (irq_type) {
> > @@ -260,10 +260,10 @@ static bool pci_endpoint_test_request_irq(struct pci_endpoint_test *test)
> >  		break;
> >  	}
> >  
> > -	return false;
> > +	return err;
> >  }
> >  
> > -static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
> > +static int pci_endpoint_test_bar(struct pci_endpoint_test *test,
> >  				  enum pci_barno barno)
> >  {
> >  	int j;
> > @@ -272,7 +272,7 @@ static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
> >  	struct pci_dev *pdev = test->pdev;
> >  
> >  	if (!test->bar[barno])
> > -		return false;
> > +		return -ENOMEM;
> 
> How is this no memory?
>

No bar means a failure in pci_ioremap_bar() during probe. And that implies a
failure while mapping the device's BAR in host memory. So -ENOMEM seems to be
the apt error no.
 
> Shouldn't this not even get here if the allocation failed?
> 

No, the driver tries to map PCI_STD_NUM_BARS which is 6 and if some of them are
not available except BAR_0 then it just logs an error and continues. So it is
not fatal.

> >  
> >  	size = pci_resource_len(pdev, barno);
> >  
> > @@ -285,13 +285,13 @@ static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
> >  	for (j = 0; j < size; j += 4) {
> >  		val = pci_endpoint_test_bar_readl(test, barno, j);
> >  		if (val != 0xA0A0A0A0)
> > -			return false;
> > +			return -EINVAL;
> 
> Is this really an invalid value sent to the ioctl?
> 
> 
> >  	}
> >  
> > -	return true;
> > +	return 0;
> >  }
> >  
> > -static bool pci_endpoint_test_legacy_irq(struct pci_endpoint_test *test)
> > +static int pci_endpoint_test_legacy_irq(struct pci_endpoint_test *test)
> >  {
> >  	u32 val;
> >  
> > @@ -303,12 +303,12 @@ static bool pci_endpoint_test_legacy_irq(struct pci_endpoint_test *test)
> >  	val = wait_for_completion_timeout(&test->irq_raised,
> >  					  msecs_to_jiffies(1000));
> >  	if (!val)
> > -		return false;
> > +		return -ETIMEDOUT;
> >  
> > -	return true;
> > +	return 0;
> >  }
> >  
> > -static bool pci_endpoint_test_msi_irq(struct pci_endpoint_test *test,
> > +static int pci_endpoint_test_msi_irq(struct pci_endpoint_test *test,
> >  				       u16 msi_num, bool msix)
> >  {
> >  	u32 val;
> > @@ -324,19 +324,18 @@ static bool pci_endpoint_test_msi_irq(struct pci_endpoint_test *test,
> >  	val = wait_for_completion_timeout(&test->irq_raised,
> >  					  msecs_to_jiffies(1000));
> >  	if (!val)
> > -		return false;
> > +		return -ETIMEDOUT;
> >  
> > -	if (pci_irq_vector(pdev, msi_num - 1) == test->last_irq)
> > -		return true;
> > +	if (pci_irq_vector(pdev, msi_num - 1) != test->last_irq)
> > +		return -EINVAL;
> 
> Again, is this an invalid value passed to the ioctl?
> 
> Same for other places you are doing something and then returning this
> error value, are you sure that is correct?
> 
> -EINVAL should be "the values you sent me was incorrect", not "something
> bad happened based on what you gave me".
> 

Okay. Will revisit all of them.

Thanks,
Mani

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