netdev - [PATCH net] mlxsw: spectrum: Fix incorrect parsing depth after reload

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Date:   Thu, 9 Feb 2023 12:40:24 +0100
From:   Petr Machata <petrm@...dia.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, <netdev@...r.kernel.org>
CC:     Ido Schimmel <idosch@...dia.com>, Petr Machata <petrm@...dia.com>,
        "Amit Cohen" <amcohen@...dia.com>, <mlxsw@...dia.com>,
        Maksym Yaremchuk <maksymy@...dia.com>
Subject: [PATCH net] mlxsw: spectrum: Fix incorrect parsing depth after reload

From: Ido Schimmel <idosch@...dia.com>

Spectrum ASICs have a configurable limit on how deep into the packet
they parse. By default, the limit is 96 bytes.

There are several cases where this parsing depth is not enough and there
is a need to increase it. For example, timestamping of PTP packets and a
FIB multipath hash policy that requires hashing on inner fields. The
driver therefore maintains a reference count that reflects the number of
consumers that require an increased parsing depth.

During reload_down() the parsing depth reference count does not
necessarily drop to zero, but the parsing depth itself is restored to
the default during reload_up() when the firmware is reset. It is
therefore possible to end up in situations where the driver thinks that
the parsing depth was increased (reference count is non-zero), when it
is not.

Fix by resetting the parsing depth reference count during
initialization, as is already done for the rest of the parsing depth
related fields.

Fixes: 2d91f0803b84 ("mlxsw: spectrum: Add infrastructure for parsing configuration")
Reported-by: Maksym Yaremchuk <maksymy@...dia.com>
Signed-off-by: Ido Schimmel <idosch@...dia.com>
Tested-by: Maksym Yaremchuk <maksymy@...dia.com>
Signed-off-by: Petr Machata <petrm@...dia.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index a8f94b7544ee..642229b1f47e 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -2937,6 +2937,7 @@ static int mlxsw_sp_netdevice_event(struct notifier_block *unused,

 static void mlxsw_sp_parsing_init(struct mlxsw_sp *mlxsw_sp)
 {
+	refcount_set(&mlxsw_sp->parsing.parsing_depth_ref, 0);
 	mlxsw_sp->parsing.parsing_depth = MLXSW_SP_DEFAULT_PARSING_DEPTH;
 	mlxsw_sp->parsing.vxlan_udp_dport = MLXSW_SP_DEFAULT_VXLAN_UDP_DPORT;
 	mutex_init(&mlxsw_sp->parsing.lock);
-- 
2.39.0