linux-kernel - Re: [patch 21/39] PCI/MSI: Move pci_enable_msix

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Message-ID: <20221116162010.GA1115209@bhelgaas>
Date:   Wed, 16 Nov 2022 10:20:10 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Ashok Raj <ashok.raj@...el.com>, Jon Mason <jdmason@...zu.us>,
        Allen Hubbe <allenbh@...il.com>,
        "Ahmed S. Darwish" <darwi@...utronix.de>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [patch 21/39] PCI/MSI: Move pci_enable_msix_range() to api.c

On Fri, Nov 11, 2022 at 02:54:48PM +0100, Thomas Gleixner wrote:
> From: Ahmed S. Darwish <darwi@...utronix.de>
> 
> To distangle the maze in msi.c, all exported device-driver MSI APIs are
> now to be grouped in one file, api.c.
> 
> Move pci_enable_msix_range() and make its kernel-doc comprehensive.
> 
> Signed-off-by: Ahmed S. Darwish <darwi@...utronix.de>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

> ---
>  drivers/pci/msi/api.c | 32 ++++++++++++++++++++++++++++++++
>  drivers/pci/msi/msi.c | 30 ++++--------------------------
>  drivers/pci/msi/msi.h |  3 +++
>  3 files changed, 39 insertions(+), 26 deletions(-)
> ---
> diff --git a/drivers/pci/msi/api.c b/drivers/pci/msi/api.c
> index 63d7f8f6a284..d48050555d55 100644
> --- a/drivers/pci/msi/api.c
> +++ b/drivers/pci/msi/api.c
> @@ -58,3 +58,35 @@ void pci_disable_msi(struct pci_dev *dev)
>  	msi_unlock_descs(&dev->dev);
>  }
>  EXPORT_SYMBOL(pci_disable_msi);
> +
> +/**
> + * pci_enable_msix_range() - Enable MSI-X interrupt mode on device
> + * @dev:     the PCI device to operate on
> + * @entries: input/output parameter, array of MSI-X configuration entries
> + * @minvec:  minimum required number of MSI-X vectors
> + * @maxvec:  maximum desired number of MSI-X vectors
> + *
> + * Legacy device driver API to enable MSI-X interrupt mode on device and
> + * configure its MSI-X capability structure as appropriate.  The passed
> + * @entries array must have each of its members "entry" field set to a
> + * desired (valid) MSI-X vector number, where the range of valid MSI-X
> + * vector numbers can be queried through pci_msix_vec_count().  If
> + * successful, the driver must invoke pci_disable_msix() on cleanup.
> + *
> + * NOTE: The newer pci_alloc_irq_vectors() / pci_free_irq_vectors() API
> + * pair should, in general, be used instead.
> + *
> + * Return: number of MSI-X vectors allocated (which might be smaller
> + * than @maxvecs), where Linux IRQ numbers for such allocated vectors
> + * are saved back in the @entries array elements' "vector" field. Return
> + * -ENOSPC if less than @minvecs interrupt vectors are available.
> + * Return -EINVAL if one of the passed @entries members "entry" field
> + * was invalid or a duplicate, or if plain MSI interrupts mode was
> + * earlier enabled on device. Return other errnos otherwise.
> + */
> +int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
> +			  int minvec, int maxvec)
> +{
> +	return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
> +}
> +EXPORT_SYMBOL(pci_enable_msix_range);
> diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
> index 98f07ad9af62..6700ef1c734e 100644
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -844,10 +844,10 @@ int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
>  	}
>  }
>  
> -static int __pci_enable_msix_range(struct pci_dev *dev,
> -				   struct msix_entry *entries, int minvec,
> -				   int maxvec, struct irq_affinity *affd,
> -				   int flags)
> +int __pci_enable_msix_range(struct pci_dev *dev,
> +			    struct msix_entry *entries, int minvec,
> +			    int maxvec, struct irq_affinity *affd,
> +			    int flags)
>  {
>  	int rc, nvec = maxvec;
>  
> @@ -887,28 +887,6 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
>  }
>  
>  /**
> - * pci_enable_msix_range - configure device's MSI-X capability structure
> - * @dev: pointer to the pci_dev data structure of MSI-X device function
> - * @entries: pointer to an array of MSI-X entries
> - * @minvec: minimum number of MSI-X IRQs requested
> - * @maxvec: maximum number of MSI-X IRQs requested
> - *
> - * Setup the MSI-X capability structure of device function with a maximum
> - * possible number of interrupts in the range between @minvec and @maxvec
> - * upon its software driver call to request for MSI-X mode enabled on its
> - * hardware device function. It returns a negative errno if an error occurs.
> - * If it succeeds, it returns the actual number of interrupts allocated and
> - * indicates the successful configuration of MSI-X capability structure
> - * with new allocated MSI-X interrupts.
> - **/
> -int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
> -		int minvec, int maxvec)
> -{
> -	return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
> -}
> -EXPORT_SYMBOL(pci_enable_msix_range);
> -
> -/**
>   * pci_alloc_irq_vectors_affinity - allocate multiple IRQs for a device
>   * @dev:		PCI device to operate on
>   * @min_vecs:		minimum number of vectors required (must be >= 1)
> diff --git a/drivers/pci/msi/msi.h b/drivers/pci/msi/msi.h
> index 00bb98d5bb0e..8c4a5289432d 100644
> --- a/drivers/pci/msi/msi.h
> +++ b/drivers/pci/msi/msi.h
> @@ -88,8 +88,11 @@ static inline __attribute_const__ u32 msi_multi_mask(struct msi_desc *desc)
>  void pci_msi_shutdown(struct pci_dev *dev);
>  void pci_free_msi_irqs(struct pci_dev *dev);
>  int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec, struct irq_affinity *affd);
> +int __pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries, int minvec,
> +			    int maxvec,  struct irq_affinity *affd, int flags);
>  
>  /* Legacy (!IRQDOMAIN) fallbacks */
> +
>  #ifdef CONFIG_PCI_MSI_ARCH_FALLBACKS
>  int pci_msi_legacy_setup_msi_irqs(struct pci_dev *dev, int nvec, int type);
>  void pci_msi_legacy_teardown_msi_irqs(struct pci_dev *dev);
>