Re: [PATCH net-next v8 1/2] net: dsa: qca8k: let regmap serialize register access

[Andrew Lunn]

On Wed, Nov 04, 2026 at 01:01:28PM +0100, Yongzhao Chen wrote:
> From: Stanislaw Pal <kuncy7@xxxxxxxxx>
> 
> The regmap is created with .disable_locking, on the ground that the
> qca8k read and write callbacks do their own locking. They only lock the
> bus transaction, though. Since the driver moved to the regmap
> read/write API, regmap formats the register and parses the value in the
> map's shared work_buf, outside of the callbacks, so two concurrent
> users can swap or corrupt each other's register and value.
> 
> Most register access runs under rtnl, but not all of it: phylink's
> resolve work (mac_link_up/down) and the LED class callbacks do not, so
> a link change can race with an ethtool or LED access and write the
> wrong switch register or read back the wrong value.

Do any of these operations which don't take RTNL do an open coded
read/modify/write? Does the regmap read/modify/write operations hold
the regmap mutex over the entire operation?

	Andrew