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Re: [PATCH RFC 77/77] vxge: Update MSI/MSI-X interrupts enablement code

To: Alexander Gordeev <agordeev@redhat.com>
Subject: Re: [PATCH RFC 77/77] vxge: Update MSI/MSI-X interrupts enablement code
From: Jon Mason <jon.mason@intel.com>
Date: Wed, 2 Oct 2013 17:29:42 -0700
Cc: linux-kernel@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>, Ralf Baechle <ralf@linux-mips.org>, Michael Ellerman <michael@ellerman.id.au>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Ingo Molnar <mingo@redhat.com>, Tejun Heo <tj@kernel.org>, Dan Williams <dan.j.williams@intel.com>, Andy King <acking@vmware.com>, Matt Porter <mporter@kernel.crashing.org>, linux-pci@vger.kernel.org, linux-mips@linux-mips.org, linuxppc-dev@lists.ozlabs.org, linux390@de.ibm.com, linux-s390@vger.kernel.org, x86@kernel.org, linux-ide@vger.kernel.org, iss_storagedev@hp.com, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, e1000-devel@lists.sourceforge.net, linux-driver@qlogic.com, Solarflare linux maintainers <linux-net-drivers@solarflare.com>, "VMware, Inc." <pv-drivers@vmware.com>, linux-scsi@vger.kernel.org
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References: <cover.1380703262.git.agordeev@redhat.com> <467ce10b1df795edf80ed222816ab739fee7b0ea.1380703263.git.agordeev@redhat.com>
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On Wed, Oct 02, 2013 at 12:49:33PM +0200, Alexander Gordeev wrote:
> As result of recent re-design of the MSI/MSI-X interrupts enabling
> pattern this driver has to be updated to use the new technique to
> obtain a optimal number of MSI/MSI-X interrupts required.
> 
> Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
> ---
>  drivers/net/ethernet/neterion/vxge/vxge-main.c |   36 ++++++++++-------------
>  1 files changed, 16 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/ethernet/neterion/vxge/vxge-main.c 
> b/drivers/net/ethernet/neterion/vxge/vxge-main.c
> index b81ff8b..b4d40dd 100644
> --- a/drivers/net/ethernet/neterion/vxge/vxge-main.c
> +++ b/drivers/net/ethernet/neterion/vxge/vxge-main.c
> @@ -2297,7 +2297,21 @@ static int vxge_alloc_msix(struct vxgedev *vdev)
>       int msix_intr_vect = 0, temp;
>       vdev->intr_cnt = 0;
>  
> -start:
> +     ret = pci_msix_table_size(vdev->pdev);
> +     if (ret < 0)
> +             goto alloc_entries_failed;
> +
> +     if (ret < (vdev->no_of_vpath * 2 + 1)) {
> +             if ((max_config_vpath != VXGE_USE_DEFAULT) || (ret < 3)) {
> +                     ret = -ENOSPC;
> +                     goto alloc_entries_failed;
> +             }
> +             /* Try with less no of vector by reducing no of vpaths count */
> +             temp = (ret - 1)/2;
> +             vxge_close_vpaths(vdev, temp);
> +             vdev->no_of_vpath = temp;
> +     }

The original code was ugly (not my code, so I can say that).  I'd like
to see it a little stream lined.  Something like:


        vdev->intr_cnt = pci_msix_table_size(vdev->pdev);

        if (vdev->intr_cnt % 2 == 0)
                vdev->intr_cnt--;

        if (vdev->intr_cnt < 3 || max_config_vpath != VXGE_USE_DEFAULT)
                goto alloc_entries_failed;

        if (vdev->intr_cnt != vdev->no_of_vpath * 2 + 1) {
                vxge_close_vpaths(vdev, vdev->intr_cnt / 2);
                vdev->no_of_vpath = vdev->intr_cnt / 2;
        }


> +
>       /* Tx/Rx MSIX Vectors count */
>       vdev->intr_cnt = vdev->no_of_vpath * 2;
>  
> @@ -2347,25 +2361,7 @@ start:
>       vdev->vxge_entries[j].in_use = 0;
>  
>       ret = pci_enable_msix(vdev->pdev, vdev->entries, vdev->intr_cnt);
> -     if (ret > 0) {
> -             vxge_debug_init(VXGE_ERR,
> -                     "%s: MSI-X enable failed for %d vectors, ret: %d",
> -                     VXGE_DRIVER_NAME, vdev->intr_cnt, ret);
> -             if ((max_config_vpath != VXGE_USE_DEFAULT) || (ret < 3)) {
> -                     ret = -ENOSPC;
> -                     goto enable_msix_failed;
> -             }
> -
> -             kfree(vdev->entries);
> -             kfree(vdev->vxge_entries);
> -             vdev->entries = NULL;
> -             vdev->vxge_entries = NULL;
> -             /* Try with less no of vector by reducing no of vpaths count */
> -             temp = (ret - 1)/2;
> -             vxge_close_vpaths(vdev, temp);
> -             vdev->no_of_vpath = temp;
> -             goto start;
> -     } else if (ret < 0)
> +     if (ret)
>               goto enable_msix_failed;

Nit, space here please.

>       return 0;
>  
> -- 
> 1.7.7.6
> 

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