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

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Date:   Mon, 7 Jun 2021 19:12:34 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Dejin Zheng <zhengdejin5@...il.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 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.

...

> 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.

> 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