On Wed, 18 Mar 2020 16:17:57 +0100
Thomas Monjalon <tho...@monjalon.net> wrote:
> 17/01/2020 17:43, Ferruh Yigit:
> > On 12/22/2019 5:55 PM, Stephen Hemminger wrote:
> > > This fixes a deadlock when using KNI with bifurcated drivers.
> > > Bringing kni device up always times out when using Mellanox
> > > devices.
> > >
> > > The kernel KNI driver sends message to userspace to complete
> > > the request. For the case of bifurcated driver, this may involve
> > > an additional request to kernel to change state. This request
> > > would deadlock because KNI was holding the RTNL mutex.
> > >
> > > This was a bad design which goes back to the original code.
> > > A workaround is for KNI driver to drop RTNL while waiting.
> > > To prevent the device from disappearing while the operation
> > > is in progress, it needs to hold reference to network device
> > > while waiting.
> > >
> > > As an added benefit, an useless error check can also be removed.
> > >
> > > Fixes: 3fc5ca2f6352 ("kni: initial import")
> > > Cc: sta...@dpdk.org
> > > Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
> > > ---
> >
> > This patch cause a hang on my server, not sure what exactly was the problem
> > but
> > kernel log was continuously printing "Cannot send to req_q". Will dig more.
> >
>
> Ferruh, did you have a chance to check what is hanging?
> Stephen, is there any news on your side?
>
>
It did not hang when I tested it. The bug report is still open
