mana_alloc_queues() regenerates the RSS indirection table from the driver
default every time the queues are built, so a table installed with
"ethtool -X" is silently replaced by any operation that rebuilds them:
an MTU change, a ring-size, channel-count or private-flag change, an XDP
attach, TX-timeout reset recovery, or resume.
The driver never clears the core's IFF_RXFH_CONFIGURED, so
netif_is_rxfh_configured() keeps reporting a user table while the
hardware has been reprogrammed with the default one. "ethtool -x" then
shows a table the user did not ask for, with no indication it changed:
# ethtool -X ens1 equal 2
# ethtool -x ens1
RX flow hash indirection table for ens1 with 16 RX ring(s):
0: 0 1 0 1 0 1 0 1
8: 0 1 0 1 0 1 0 1
# ip link set ens1 mtu 1400
# ethtool -x ens1
RX flow hash indirection table for ens1 with 16 RX ring(s):
0: 0 1 2 3 4 5 6 7
8: 8 9 10 11 12 13 14 15
Keep the table instead, and rebuild it only when it is driver-generated
or cannot be honoured. An entry may not be kept if it points past the
last queue: mana_config_rss() uses these entries to index apc->rxqs[],
which holds apc->num_queues pointers. That is reachable because
mana_attach() calls mana_init_port(), which lowers apc->num_queues to the
maximum the device reports, so a table configured for more queues can
outlive them.
A table that cannot be kept is still replaced by the default silently,
without ethtool_rxfh_indir_lost(). That helper sends
ETHTOOL_MSG_RSS_NTF, which requires the netdev instance lock, and
mana_alloc_queues() runs both with that lock held, from ndo_open, and
without it, from mana_attach() on the reset and resume paths. Leaving
the core's view untouched is what the driver did for every table before
this change.
Opt the RSS ethtool operations into rtnl_lock() while here. Reading the
table in mana_alloc_queues() has to be serialized against mana_set_rxfh()
replacing it, and the two had no lock in common: mana_set_rxfh() ran under
the netdev instance lock alone, while mana_alloc_queues() reaches this
point holding only RTNL, from ndo_open and from mana_attach() on the reset
and resume paths. Taking the instance lock there instead is not possible,
since ndo_open already runs with it held. The same flag covers the netlink
and ioctl entry points.
Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network
Adapter (MANA)")
Signed-off-by: Long Li <[email protected]>
---
drivers/net/ethernet/microsoft/mana/mana_en.c | 37 ++++++++++++++++++-
.../ethernet/microsoft/mana/mana_ethtool.c | 3 +-
2 files changed, 38 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
b/drivers/net/ethernet/microsoft/mana/mana_en.c
index
7a1ac853e3abcd28c4a1e5c6987ec631a18ad840..97386e17b9421aedefa25bab6fbf0b7b1f2996d4
100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -3306,6 +3306,28 @@ static void mana_rss_table_init(struct mana_port_context
*apc)
ethtool_rxfh_indir_default(i, apc->num_queues);
}
+/* Whether the current indirection table can be kept for apc->num_queues,
+ * rather than rebuilt from the driver default.
+ *
+ * Only a user table ("ethtool -X") is worth keeping; a driver-generated one
+ * is rebuilt so that it spreads over every queue. An entry pointing past the
+ * last queue cannot be kept: mana_config_rss() uses these entries to index
+ * apc->rxqs[], which holds apc->num_queues pointers.
+ */
+static bool mana_rss_table_keep(struct mana_port_context *apc)
+{
+ u32 i;
+
+ if (!netif_is_rxfh_configured(apc->ndev))
+ return false;
+
+ for (i = 0; i < apc->indir_table_sz; i++)
+ if (apc->indir_table[i] >= apc->num_queues)
+ return false;
+
+ return true;
+}
+
int mana_disable_vport_rx(struct mana_port_context *apc)
{
return mana_cfg_vport_steering(apc, TRI_STATE_FALSE, false, false,
@@ -3621,7 +3643,20 @@ int mana_alloc_queues(struct net_device *ndev)
goto destroy_rxq;
}
- mana_rss_table_init(apc);
+ /* Keep a user-configured table across the rebuild: its entries are
+ * queue indices and stay meaningful while they are all still in range.
+ * Only a driver-generated table is regenerated here.
+ *
+ * A table that cannot be kept is replaced by the default without
+ * telling the core, which keeps reporting the table as user
+ * configured. That is what this function did for every table before,
+ * and reporting it here is not an option: ethtool_rxfh_indir_lost()
+ * sends ETHTOOL_MSG_RSS_NTF, which requires the netdev instance lock,
+ * and this runs both with that lock held (ndo_open) and without it
+ * (mana_attach() from the reset and resume paths).
+ */
+ if (!mana_rss_table_keep(apc))
+ mana_rss_table_init(apc);
err = mana_config_rss(apc, TRI_STATE_TRUE, true, true);
if (err) {
diff --git a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
index
ece7ff9cc409a806b6a6de70a85b44874bfa6dad..e3acaf17efabcd62f7cffabdb8404cf16b917272
100644
--- a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
@@ -871,7 +871,8 @@ const struct ethtool_ops mana_ethtool_ops = {
.op_needs_rtnl = ETHTOOL_OP_NEEDS_RTNL_SCHANNELS |
ETHTOOL_OP_NEEDS_RTNL_SRINGPARAM |
ETHTOOL_OP_NEEDS_RTNL_SPFLAGS |
- ETHTOOL_OP_NEEDS_RTNL_GLINK,
+ ETHTOOL_OP_NEEDS_RTNL_GLINK |
+ ETHTOOL_OP_NEEDS_RTNL_RSS,
.get_ethtool_stats = mana_get_ethtool_stats,
.get_sset_count = mana_get_sset_count,
.get_strings = mana_get_strings,
--
2.43.0
