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    Subject[PATCH 5.4 169/355] net: dsa: lantiq_gswip: serialize access to the PCE table
    Date
    From: Vladimir Oltean <vladimir.oltean@nxp.com>

    [ Upstream commit 49753a75b9a32de4c0393bb8d1e51ea223fda8e4 ]

    Looking at the code, the GSWIP switch appears to hold bridging service
    structures (VLANs, FDBs, forwarding rules) in PCE table entries.
    Hardware access to the PCE table is non-atomic, and is comprised of
    several register reads and writes.

    These accesses are currently serialized by the rtnl_lock, but DSA is
    changing its driver API and that lock will no longer be held when
    calling ->port_fdb_add() and ->port_fdb_del().

    So this driver needs to serialize the access to the PCE table using its
    own locking scheme. This patch adds that.

    Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
    Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
    Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/dsa/lantiq_gswip.c | 28 +++++++++++++++++++++++-----
    1 file changed, 23 insertions(+), 5 deletions(-)

    diff --git a/drivers/net/dsa/lantiq_gswip.c b/drivers/net/dsa/lantiq_gswip.c
    index 60e36f46f8abe..d612ef8648baa 100644
    --- a/drivers/net/dsa/lantiq_gswip.c
    +++ b/drivers/net/dsa/lantiq_gswip.c
    @@ -274,6 +274,7 @@ struct gswip_priv {
    int num_gphy_fw;
    struct gswip_gphy_fw *gphy_fw;
    u32 port_vlan_filter;
    + struct mutex pce_table_lock;
    };

    struct gswip_pce_table_entry {
    @@ -521,10 +522,14 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
    u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSRD :
    GSWIP_PCE_TBL_CTRL_OPMOD_ADRD;

    + mutex_lock(&priv->pce_table_lock);
    +
    err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
    GSWIP_PCE_TBL_CTRL_BAS);
    - if (err)
    + if (err) {
    + mutex_unlock(&priv->pce_table_lock);
    return err;
    + }

    gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
    gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
    @@ -534,8 +539,10 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,

    err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
    GSWIP_PCE_TBL_CTRL_BAS);
    - if (err)
    + if (err) {
    + mutex_unlock(&priv->pce_table_lock);
    return err;
    + }

    for (i = 0; i < ARRAY_SIZE(tbl->key); i++)
    tbl->key[i] = gswip_switch_r(priv, GSWIP_PCE_TBL_KEY(i));
    @@ -551,6 +558,8 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
    tbl->valid = !!(crtl & GSWIP_PCE_TBL_CTRL_VLD);
    tbl->gmap = (crtl & GSWIP_PCE_TBL_CTRL_GMAP_MASK) >> 7;

    + mutex_unlock(&priv->pce_table_lock);
    +
    return 0;
    }

    @@ -563,10 +572,14 @@ static int gswip_pce_table_entry_write(struct gswip_priv *priv,
    u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSWR :
    GSWIP_PCE_TBL_CTRL_OPMOD_ADWR;

    + mutex_lock(&priv->pce_table_lock);
    +
    err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
    GSWIP_PCE_TBL_CTRL_BAS);
    - if (err)
    + if (err) {
    + mutex_unlock(&priv->pce_table_lock);
    return err;
    + }

    gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
    gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
    @@ -598,8 +611,12 @@ static int gswip_pce_table_entry_write(struct gswip_priv *priv,
    crtl |= GSWIP_PCE_TBL_CTRL_BAS;
    gswip_switch_w(priv, crtl, GSWIP_PCE_TBL_CTRL);

    - return gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
    - GSWIP_PCE_TBL_CTRL_BAS);
    + err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
    + GSWIP_PCE_TBL_CTRL_BAS);
    +
    + mutex_unlock(&priv->pce_table_lock);
    +
    + return err;
    }

    /* Add the LAN port into a bridge with the CPU port by
    @@ -2020,6 +2037,7 @@ static int gswip_probe(struct platform_device *pdev)
    priv->ds->priv = priv;
    priv->ds->ops = &gswip_switch_ops;
    priv->dev = dev;
    + mutex_init(&priv->pce_table_lock);
    version = gswip_switch_r(priv, GSWIP_VERSION);

    /* bring up the mdio bus */
    --
    2.33.0


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