Re: [PATCH v4 net-next 5/9] net: dsa: lantiq_gswip: serialize access to the PCE table

[Hauke Mehrtens <hauke@hauke-m.de>]

On 10/22/21 8:43 PM, Vladimir Oltean wrote:
> 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.

The switch has multiple tables which can be accessed with indirect 
addressing over the PCE registers.

> 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.

The driver also uses the gswip_pce_load_microcode() function to load a 
static configuration for the packet classification engine into a table 
using the same registers. It is currently not protected, but only called 
by the DSA setup callback.

> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
> v3->v4: call mutex_init
> 
>   drivers/net/dsa/lantiq_gswip.c | 28 +++++++++++++++++++++++-----
>   1 file changed, 23 insertions(+), 5 deletions(-)
> 
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>