> -----Original Message----- > From: Stephen Hemminger [mailto:step...@networkplumber.org] > Sent: Wednesday, September 6, 2017 11:19 AM > To: KY Srinivasan <k...@microsoft.com>; Haiyang Zhang > <haiya...@microsoft.com>; Stephen Hemminger <sthem...@microsoft.com> > Cc: de...@linuxdriverproject.org; net...@vger.kernel.org > Subject: [PATCH net-next 1/1] hv_netvsc: fix deadlock on hotplug > > When a virtual device is added dynamically (via host console), then > the vmbus sends an offer message for the primary channel. The processing > of this message for networking causes the network device to then > initialize the sub channels. > > The problem is that setting up the sub channels needs to wait until > the subsequent subchannel offers have been processed. These offers > come in on the same ring buffer and work queue as where the primary > offer is being processed; leading to a deadlock. > > This did not happen in older kernels, because the sub channel waiting > logic was broken (it wasn't really waiting). > > The solution is to do the sub channel setup in its own work queue > context that is scheduled by the primary channel setup; and then > happens later. > > Fixes: 732e49850c5e ("netvsc: fix race on sub channel creation") > Reported-by: Dexuan Cui <de...@microsoft.com> > Signed-off-by: Stephen Hemminger <sthem...@microsoft.com> > --- > Should also go to stable, but this version does not apply cleanly > to 4.13. Have another patch for that. > > drivers/net/hyperv/hyperv_net.h | 1 + > drivers/net/hyperv/netvsc_drv.c | 8 +-- > drivers/net/hyperv/rndis_filter.c | 106 ++++++++++++++++++++++++++----- > ------- > 3 files changed, 74 insertions(+), 41 deletions(-)
The patch looks overall. I just have a question: With this patch, after module load and probe is done, there may still be subchannels being processed. If rmmod immediately, the subchannel offers may hit half-way removed device structures... Do we also need to add cancel_work_sync(&dev->subchan_work) to the top of netvsc_remove()? unregister_netdevice() includes device close, but it's only called later in the netvsc_remove() when rndis is already removed. Thanks, - Haiyang _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
