linux-kernel - Re: [PATCH] PCI/IOV: Expose error return to dmesg

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Date:   Tue, 13 Dec 2022 11:01:46 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Liming Wu <liming.wu@...uarmicro.com>
Cc:     bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
        398776277@...com
Subject: Re: [PATCH] PCI/IOV: Expose error return to dmesg

On Tue, Dec 13, 2022 at 04:16:07PM +0800, Liming Wu wrote:
> There are many errors returned during the initialization of sriov,
> such as -EIO/-ENOMEM, but they are not exposed to dmesg.
> Let's expose the real errors to the user.

Please provide motivation. It is pretty easy to see what went wrong
even without info print in dmesg.

> 
> In addition, -ENODEV doesn't make much sense and is not returned
> just like any other capabilities.
> 
> Signed-off-by: Liming Wu <liming.wu@...uarmicro.com>
> ---
>  drivers/pci/iov.c   | 9 ++++++---
>  drivers/pci/pci.h   | 2 --
>  drivers/pci/probe.c | 6 +++++-
>  3 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 952217572113..519aa2b48236 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -767,8 +767,11 @@ static int sriov_init(struct pci_dev *dev, int pos)
>  	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
>  
>  	pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total);
> -	if (!total)
> +	if (!total) {
> +		pci_info(dev, "SR-IOV capability is enabled but has %d VFs)\n",
> +			total);

total is always 0 in this print.

>  		return 0;
> +	}
>  
>  	pci_read_config_dword(dev, pos + PCI_SRIOV_SUP_PGSIZE, &pgsz);
>  	i = PAGE_SHIFT > 12 ? PAGE_SHIFT - 12 : 0;
> @@ -899,13 +902,13 @@ int pci_iov_init(struct pci_dev *dev)
>  	int pos;
>  
>  	if (!pci_is_pcie(dev))
> -		return -ENODEV;
> +		return;

Please at least compile patches before you send them.

>  
>  	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_SRIOV);
>  	if (pos)
>  		return sriov_init(dev, pos);
>  
> -	return -ENODEV;
> +	return;
>  }
>  
>  /**
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index b1ebb7ab8805..c4836104f697 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -485,10 +485,8 @@ extern const struct attribute_group sriov_vf_dev_attr_group;
>  #else
>  static inline int pci_iov_init(struct pci_dev *dev)
>  {
> -	return -ENODEV;
>  }
>  static inline void pci_iov_release(struct pci_dev *dev)
> -
>  {
>  }
>  static inline void pci_iov_remove(struct pci_dev *dev)
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index b66fa42c4b1f..c951e0a50388 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2449,6 +2449,7 @@ void pcie_report_downtraining(struct pci_dev *dev)
>  
>  static void pci_init_capabilities(struct pci_dev *dev)
>  {
> +	int ret;
>  	pci_ea_init(dev);		/* Enhanced Allocation */
>  	pci_msi_init(dev);		/* Disable MSI */
>  	pci_msix_init(dev);		/* Disable MSI-X */
> @@ -2459,7 +2460,10 @@ static void pci_init_capabilities(struct pci_dev *dev)
>  	pci_pm_init(dev);		/* Power Management */
>  	pci_vpd_init(dev);		/* Vital Product Data */
>  	pci_configure_ari(dev);		/* Alternative Routing-ID Forwarding */
> -	pci_iov_init(dev);		/* Single Root I/O Virtualization */
> +	ret = pci_iov_init(dev);		/* Single Root I/O Virtualization */
> +	if (ret)
> +		pci_err(dev, "SR-IOV: init failed (%d)\n", ret);
> +
>  	pci_ats_init(dev);		/* Address Translation Services */
>  	pci_pri_init(dev);		/* Page Request Interface */
>  	pci_pasid_init(dev);		/* Process Address Space ID */
> -- 
> 2.25.1
>