Re: [PATCH 5.15 291/917] net: dsa: lantiq_gswip: serialize access to the PCE table

Sasha Levin
2021-11-16T01:52:09Z

On Mon, Nov 15, 2021 at 11:35:47PM +0000, Vladimir Oltean wrote:
>On Mon, Nov 15, 2021 at 05:56:26PM +0100, Greg Kroah-Hartman wrote:
>> 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 dbd4486a173ff..1a96df70d1e85 100644
>> --- a/drivers/net/dsa/lantiq_gswip.c
>> +++ b/drivers/net/dsa/lantiq_gswip.c
>> @@ -276,6 +276,7 @@ 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 {
>> @@ -523,10 +524,14 @@ 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 |
>> @@ -536,8 +541,10 @@ 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));
>> @@ -553,6 +560,8 @@ 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;
>> }
>>
>> @@ -565,10 +574,14 @@ 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 |
>> @@ -600,8 +613,12 @@ 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
>> @@ -2106,6 +2123,7 @@ static int gswip_probe(struct platform_device *pdev)
>> priv->ds->priv = priv;
>> priv->ds->ops = priv->hw_info->ops;
>> priv->dev = dev;
>> + mutex_init(&priv->pce_table_lock);
>> version = gswip_switch_r(priv, GSWIP_VERSION);
>>
>> np = dev->of_node;
>> --
>> 2.33.0
>>
>>
>>
>
>As discussed on the v5.14 backport, this patch can be dropped.

Dropped, thanks!

--
Thanks,
Sasha