This is a note to let you know that I've just added the patch titled mlxsw: spectrum_qdisc: Ignore grafting of invisible FIFO to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mlxsw-spectrum_qdisc-ignore-grafting-of-invisible-fifo.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sat 11 Jan 2020 09:14:34 AM CET From: Petr Machata <petrm@xxxxxxxxxxxx> Date: Mon, 6 Jan 2020 18:01:55 +0000 Subject: mlxsw: spectrum_qdisc: Ignore grafting of invisible FIFO From: Petr Machata <petrm@xxxxxxxxxxxx> [ Upstream commit 3971a535b839489e4ea31796cc086e6ce616318c ] The following patch will change PRIO to replace a removed Qdisc with an invisible FIFO, instead of NOOP. mlxsw will see this replacement due to the graft message that is generated. But because FIFO does not issue its own REPLACE message, when the graft operation takes place, the Qdisc that mlxsw tracks under the indicated band is still the old one. The child handle (0:0) therefore does not match, and mlxsw rejects the graft operation, which leads to an extack message: Warning: Offloading graft operation failed. Fix by ignoring the invisible children in the PRIO graft handler. The DESTROY message of the removed Qdisc is going to follow shortly and handle the removal. Fixes: 32dc5efc6cb4 ("mlxsw: spectrum: qdiscs: prio: Handle graft command") Signed-off-by: Petr Machata <petrm@xxxxxxxxxxxx> Acked-by: Jiri Pirko <jiri@xxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c @@ -650,6 +650,13 @@ mlxsw_sp_qdisc_prio_graft(struct mlxsw_s mlxsw_sp_port->tclass_qdiscs[tclass_num].handle == p->child_handle) return 0; + if (!p->child_handle) { + /* This is an invisible FIFO replacing the original Qdisc. + * Ignore it--the original Qdisc's destroy will follow. + */ + return 0; + } + /* See if the grafted qdisc is already offloaded on any tclass. If so, * unoffload it. */ Patches currently in stable-queue which might be from petrm@xxxxxxxxxxxx are queue-4.19/net-sch_prio-when-ungrafting-replace-with-fifo.patch queue-4.19/mlxsw-spectrum_qdisc-ignore-grafting-of-invisible-fifo.patch