Re: [PATCH net] net: stmmac: Disable Tx queues when reconfiguring the interface

[Vladimir Oltean <vladimir.oltean@nxp.com>]

On Wed, Nov 24, 2021 at 01:10:55PM +0100, Yannick Vignon wrote:
> On 11/24/2021 11:06 AM, Vladimir Oltean wrote:
> > On Tue, Nov 23, 2021 at 08:07:51PM -0800, Jakub Kicinski wrote:
> > > On Tue, 23 Nov 2021 19:54:48 +0100 Yannick Vignon wrote:
> > > > From: Yannick Vignon <yannick.vignon@nxp.com>
> > > > 
> > > > The Tx queues were not disabled in cases where the driver needed to stop
> > > > the interface to apply a new configuration. This could result in a kernel
> > > > panic when doing any of the 3 following actions:
> > > > * reconfiguring the number of queues (ethtool -L)
> > > > * reconfiguring the size of the ring buffers (ethtool -G)
> > > > * installing/removing an XDP program (ip l set dev ethX xdp)
> > > > 
> > > > Prevent the panic by making sure netif_tx_disable is called when stopping
> > > > an interface.
> > > > 
> > > > Without this patch, the following kernel panic can be observed when loading
> > > > an XDP program:
> > > > 
> > > > Unable to handle kernel paging request at virtual address ffff80001238d040
> > > > [....]
> > > >   Call trace:
> > > >    dwmac4_set_addr+0x8/0x10
> > > >    dev_hard_start_xmit+0xe4/0x1ac
> > > >    sch_direct_xmit+0xe8/0x39c
> > > >    __dev_queue_xmit+0x3ec/0xaf0
> > > >    dev_queue_xmit+0x14/0x20
> > > > [...]
> > > > [ end trace 0000000000000002 ]---
> > > > 
> > > > Fixes: 78cb988d36b6 ("net: stmmac: Add initial XDP support")
> > > > Signed-off-by: Yannick Vignon <yannick.vignon@nxp.com>
> > > 
> > > Fixes tag: Fixes: 78cb988d36b6 ("net: stmmac: Add initial XDP support")
> > > Has these problem(s):
> > > 	- Target SHA1 does not exist
> > 
> > You caught him backporting! Although I agree, things sent to the "net"
> > tree should also be tested against the "net" tree.
> > 
> 
> That would be more like forward-porting in this case, since I first fixed
> the issue on an older 5.10 kernel :)

XDP for stmmac isn't in v5.10, so backporting is what it is.