linux-kernel - Re: [PATCH v7 1/4] PCI: Introduce pcim_alloc_irq

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Date:   Tue, 8 Jun 2021 22:20:11 +0800
From:   Dejin Zheng <zhengdejin5@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     helgaas@...nel.org, corbet@....net, jarkko.nikula@...ux.intel.com,
        mika.westerberg@...ux.intel.com, rric@...nel.org,
        bhelgaas@...gle.com, wsa@...nel.org, Sanket.Goswami@....com,
        linux-doc@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v7 1/4] PCI: Introduce pcim_alloc_irq_vectors()

On Mon, Jun 07, 2021 at 07:12:34PM +0300, Andy Shevchenko wrote:
> On Mon, Jun 07, 2021 at 11:39:13PM +0800, Dejin Zheng wrote:
> > Introduce pcim_alloc_irq_vectors(), a device-managed version of
> > pci_alloc_irq_vectors(). Introducing this function can simplify
> > the error handling path in many drivers.
> > 
> > And use pci_free_irq_vectors() to replace some code in pcim_release(),
> > they are equivalent, and no functional change. It is more explicit
> > that pcim_alloc_irq_vectors() is a device-managed function.
> 
> ...
> 
> > When CONFIG_PCI=n, there is no stub for pci_is_managed(), but
> > pcim_alloc_irq_vectors() will use it, so add one like other similar stubs.
> > Otherwise there can be build errors, as here by kernel test robot
> > reported:
> > include/linux/pci.h: In function 'pcim_alloc_irq_vectors':
> > >> include/linux/pci.h:1847:7: error: implicit declaration of function 'pci_is_managed' [-Werror=implicit-function-declaration]
> >     1847 |  if (!pci_is_managed(dev))
> >          |       ^~~~~~~~~~~~~~
> 
> This is rather changelog related material. No need to pollute commit message
> with this.
>
Okey.

> ...
> 
> > Reported-by: kernel test robot <lkp@...el.com>
> 
> It's new functionality. Why this tag is here?
> Use comments (similar location than changelog) to give a credit if you wish.
>
Got it, Thanks!

> > Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > Reviewed-by: Robert Richter <rric@...nel.org>
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
> > Signed-off-by: Dejin Zheng <zhengdejin5@...il.com>
> > ---
> > v6 -> v7:
> > 	- rebase to PCI next branch
> > 	- add a stub for pci_is_managed() when disable PCI for
> > 	  fix build error in sparc architecture.
> > v5 -> v6:
> > 	- rebase to 5.13-rc4
> > v4 -> v5:
> > 	- Remove the check of enable device in pcim_alloc_irq_vectors()
> > 	  and make it as a static line function.
> > v3 -> v4:
> > 	- No change
> > v2 -> v3:
> > 	- Add some commit comments for replace some codes in
> > 	  pcim_release() by pci_free_irq_vectors().
> > v1 -> v2:
> > 	- Use pci_free_irq_vectors() to replace some code in
> > 	  pcim_release().
> > 	- Modify some commit messages.
> > 
> >  drivers/pci/pci.c   |  5 +----
> >  include/linux/pci.h | 25 +++++++++++++++++++++++++
> >  2 files changed, 26 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 452351025a09..e3b3fc59bd35 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -1989,10 +1989,7 @@ static void pcim_release(struct device *gendev, void *res)
> >  	struct pci_devres *this = res;
> >  	int i;
> >  
> > -	if (dev->msi_enabled)
> > -		pci_disable_msi(dev);
> > -	if (dev->msix_enabled)
> > -		pci_disable_msix(dev);
> > +	pci_free_irq_vectors(dev);
> >  
> >  	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
> >  		if (this->region_mask & (1 << i))
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index c20211e59a57..5783262c4643 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -1730,6 +1730,7 @@ static inline struct pci_dev *pci_get_class(unsigned int class,
> >  
> >  static inline void pci_set_master(struct pci_dev *dev) { }
> >  static inline int pci_enable_device(struct pci_dev *dev) { return -EIO; }
> > +static inline int pci_is_managed(struct pci_dev *pdev) { return 0; }
> >  static inline void pci_disable_device(struct pci_dev *dev) { }
> >  static inline int pcim_enable_device(struct pci_dev *pdev) { return -EIO; }
> >  static inline int pci_assign_resource(struct pci_dev *dev, int i)
> > @@ -1825,6 +1826,30 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> >  					      NULL);
> >  }
> >  
> > +/**
> > + * pcim_alloc_irq_vectors - a device-managed pci_alloc_irq_vectors()
> > + * @dev:		PCI device to operate on
> > + * @min_vecs:		minimum number of vectors required (must be >= 1)
> > + * @max_vecs:		maximum (desired) number of vectors
> > + * @flags:		flags or quirks for the allocation
> > + *
> > + * Return the number of vectors allocated, (which might be smaller than
> > + * @max_vecs) if successful, or a negative error code on error. If less
> > + * than @min_vecs interrupt vectors are available for @dev the function
> > + * will fail with -ENOSPC.
> > + *
> > + * It depends on calling pcim_enable_device() to make IRQ resources
> > + * manageable.
> > + */
> > +static inline int
> > +pcim_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> > +			unsigned int max_vecs, unsigned int flags)
> > +{
> > +	if (!pci_is_managed(dev))
> > +		return -EINVAL;
> > +	return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
> > +}
> > +
> >  /* Include architecture-dependent settings and functions */
> >  
> >  #include <asm/pci.h>
> > -- 
> > 2.30.1
> > 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>