linux-kernel - Re: [PATCH] misc/GenWQE: fix pci_enable

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Date:	Wed, 9 Jul 2014 13:34:53 +0200
From:	Alexander Gordeev <agordeev@...hat.com>
To:	Sebastian Ott <sebott@...ux.vnet.ibm.com>
Cc:	Frank Haverkamp <haver@...ux.vnet.ibm.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] misc/GenWQE: fix pci_enable_msi usage

On Wed, Jul 09, 2014 at 12:46:39PM +0200, Sebastian Ott wrote:
> GenWQE used to call pci_enable_msi_block to allocate a desired number
> of MSI's. If that was not possible pci_enable_msi_block returned with a
> smaller number which might be possible to allocate. GenWQE then called
> pci_enable_msi_block with that number.
> 
> Since commit a30d0108b
> "GenWQE: Use pci_enable_msi_exact() instead of pci_enable_msi_block()"
> pci_enable_msi_exact is used which fails if the desired number of MSI's
> was not possible to allocate. Change GenWQE to use pci_enable_msi_range
> to restore the old behavior.
> 
> Signed-off-by: Sebastian Ott <sebott@...ux.vnet.ibm.com>
> ---
>  drivers/misc/genwqe/card_ddcb.c  |  4 +---
>  drivers/misc/genwqe/card_utils.c | 10 ++++++----
>  2 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/misc/genwqe/card_ddcb.c b/drivers/misc/genwqe/card_ddcb.c
> index c8046db..f66d43d 100644
> --- a/drivers/misc/genwqe/card_ddcb.c
> +++ b/drivers/misc/genwqe/card_ddcb.c
> @@ -1237,9 +1237,7 @@ int genwqe_setup_service_layer(struct genwqe_dev *cd)
>  	}
>  
>  	rc = genwqe_set_interrupt_capability(cd, GENWQE_MSI_IRQS);
> -	if (rc > 0)
> -		rc = genwqe_set_interrupt_capability(cd, rc);
> -	if (rc != 0) {
> +	if (rc) {
>  		rc = -ENODEV;
>  		goto stop_kthread;
>  	}
> diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c
> index 62cc6bb..6abc437 100644
> --- a/drivers/misc/genwqe/card_utils.c
> +++ b/drivers/misc/genwqe/card_utils.c
> @@ -718,10 +718,12 @@ int genwqe_set_interrupt_capability(struct genwqe_dev *cd, int count)
>  	int rc;
>  	struct pci_dev *pci_dev = cd->pci_dev;
>  
> -	rc = pci_enable_msi_exact(pci_dev, count);
> -	if (rc == 0)
> -		cd->flags |= GENWQE_FLAG_MSI_ENABLED;
> -	return rc;
> +	rc = pci_enable_msi_range(pci_dev, 1, count);
> +	if (rc < 0)
> +		return rc;
> +
> +	cd->flags |= GENWQE_FLAG_MSI_ENABLED;
> +	return 0;
>  }
>  
>  /**
> -- 
> 1.9.3
> 

Reviewed-by: Alexander Gordeev <agordeev@...hat.com>

I am curious though why would you need convert error code to -ENODEV here
(and throughout the code in general)?

Thanks!

-- 
Regards,
Alexander Gordeev
agordeev@...hat.com
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