Re: [PATCH] igb_uio: issue FLR during open and release of device file

[Shijith Thotton <shijith.thotton@caviumnetworks.com>]

On Thu, Jul 06, 2017 at 08:27:17PM +0300, Gregory Etelson wrote:
> I could not reproduce server crash with http://dpdk.org/dev/patchwork/patch/25267/ [1]
> However, pci_try_reset_function() API used in that patch is not defined in RedHat-6.x Linux-2.6.32 kernels 
> Therefore I work with http://dpdk.org/dev/patchwork/patch/25061/  patch [2].
> [2] was successfully tested with IXGBE & I40e VFs on RH 6.x, RH 7.x Ubuntu 14.04 and SLES-11.4 
>  
> Regards,
> Gregory
> 
> On Thursday, 6 July 2017 19:41:40 IDT Ferruh Yigit wrote:
> > On 6/12/2017 10:38 AM, Shijith Thotton wrote:
> > > Set UIO info device file operations open and release. Call pci reset
> > > function inside open and release to clear device state at start and end.
> > > Copied this behaviour from vfio_pci kernel module code. With this patch,
> > > it is not mandatory to issue FLR by PMD's during init and close.
> > > 
> > > Bus master enable and disable are added in open and release respectively
> > > to take care of device DMA.
> > > 
> > > Signed-off-by: Shijith Thotton <shijith.thotton@caviumnetworks.com>
> > 
> > This patch, and Gregory's patch [1] are very similar and main target is
> > to leave device in a more proper state when DPDK application quits
> > unexpectedly.
> > 
> > Difference between two are, this one implements both .open and .release
> > ops, and sets / clears bus master accordingly.
> > 
> > Although main concern is .reset, I am OK to follow vfio_pci approach
> > here, and clearing bus master on .reset can prevent unwanted DMA access.
> > 
> > So, I am for this patch and I am testing it for a few days without a
> > problem.
> > 
> > But Gregory reported a crash with older version of this patch, without
> > more detail, we should clear that first. With Gregory's Tested-by, I am
> > OK with this patch.
> > 
> > 
> > Gregory,
> > 
> > Are you using your version, what are the results? And would you mind
> > testing this patch?
> > 
> > Thanks,
> > ferruh
> > 
> > 
> > [1]
> > http://dpdk.org/dev/patchwork/patch/25061/
> > 
> > 

Hi Gregory,

Please try the following change:
s/pci_try_reset_function/pci_reset_function/

pci_try_reset_function is same as pci_reset_function, except it returns -EAGAIN
if unable to lock the device[1].

If everyone agrees, I can submit v2 with this change.

1. http://elixir.free-electrons.com/linux/latest/source/drivers/pci/pci.c#L4293

Thanks,
Shijith