Message-ID: <333dee5b-6710-998c-bf3f-2cb1d676a7da@oracle.com>
Date:   Sat, 11 Feb 2023 02:15:40 +0530
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Subject: Re: [PATCH] PCI: Fix build error when CONFIG_PCI_MSI disabled
Content-Language: en-US
To:     Reinette Chatre <reinette.chatre@intel.com>, bhelgaas@google.com,
        nathan@kernel.org, ndesaulniers@google.com, trix@redhat.com
Cc:     linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, tglx@linutronix.de, kevin.tian@intel.com,
        darwi@linutronix.de
References: <158e40e1cfcfc58ae30ecb2bbfaf86e5bba7a1ef.1675978686.git.reinette.chatre@intel.com>
From:   ALOK TIWARI <alok.a.tiwari@oracle.com>
Organization: Oracle Corporation
In-Reply-To: <158e40e1cfcfc58ae30ecb2bbfaf86e5bba7a1ef.1675978686.git.reinette.chatre@intel.com>
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shall we need to define this function under -> #ifndef CONFIG_PCI_MSI

#ifndef CONFIG_PCI_MSI

+static inline struct msi_map
+pci_msix_alloc_irq_at(struct pci_dev *dev, unsigned int index,
+		      const struct irq_affinity_desc *affdesc)
+{
+	struct msi_map map = { .index = -ENOSYS };
+
+	return map;
+}
+
+static inline void pci_msix_free_irq(struct pci_dev *pdev, struct msi_map map)
+{
+}
+#endif

Thanks,

Alok

On 2/10/2023 3:19 AM, Reinette Chatre wrote:
> pci_msix_alloc_irq_at() and pci_msix_free_irq() are not
> declared when CONFIG_PCI_MSI is disabled.
>
> Users of these two calls do not yet exist but when users
> do appear (shown below is an attempt to use the new API
> in vfio-pci) the following errors will be encountered when
> compiling with CONFIG_PCI_MSI disabled:
> drivers/vfio/pci/vfio_pci_intrs.c:461:4: error: implicit declaration of\
>          function 'pci_msix_free_irq' is invalid in C99\
>          [-Werror,-Wimplicit-function-declaration]
>                             pci_msix_free_irq(pdev, msix_map);
>                             ^
>     drivers/vfio/pci/vfio_pci_intrs.c:461:4: note: did you mean 'pci_ims_free_irq'?
>     include/linux/pci.h:2516:6: note: 'pci_ims_free_irq' declared here
>     void pci_ims_free_irq(struct pci_dev *pdev, struct msi_map map);
>          ^
> drivers/vfio/pci/vfio_pci_intrs.c:511:15: error: implicit declaration of\
>          function 'pci_msix_alloc_irq_at' is invalid in C99\
>          [-Werror,-Wimplicit-function-declaration]
>                     msix_map = pci_msix_alloc_irq_at(pdev, vector, NULL);
>                                        ^
>     drivers/vfio/pci/vfio_pci_intrs.c:511:15: note: did you mean 'pci_ims_alloc_irq'?
>     include/linux/pci.h:2514:16: note: 'pci_ims_alloc_irq' declared here
>     struct msi_map pci_ims_alloc_irq(struct pci_dev *pdev,\
>                                      union msi_instance_cookie *icookie,
>
> Provide definitions for pci_msix_alloc_irq_at() and pci_msix_free_irq() in
> preparation for users that need to compile when CONFIG_PCI_MSI is
> disabled.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
> ---
>
> checkpatch.pl warns about the usage of -ENOSYS but it does appear
> to be the custom.
>
>   include/linux/pci.h | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index adffd65e84b4..448482d1c4fe 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1621,6 +1621,19 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
>   					      flags, NULL);
>   }
>   
> +static inline struct msi_map
> +pci_msix_alloc_irq_at(struct pci_dev *dev, unsigned int index,
> +		      const struct irq_affinity_desc *affdesc)
> +{
> +	struct msi_map map = { .index = -ENOSYS };
> +
> +	return map;
> +}
> +
> +static inline void pci_msix_free_irq(struct pci_dev *pdev, struct msi_map map)
> +{
> +}
> +
>   static inline void pci_free_irq_vectors(struct pci_dev *dev)
>   {
>   }