On Fri, 17 Jan 2025 13:57:41 +0200
Claudiu Beznea <claudiu.beznea@xxxxxxxxx> wrote:
> Hi, Kory,
>
> On 12.12.2024 19:06, Kory Maincent wrote:
> > Introduce the description of a hwtstamp provider, mainly defined with a
> > the hwtstamp source and the phydev pointer.
> >
> > Add a hwtstamp provider description within the netdev structure to
> > allow saving the hwtstamp we want to use. This prepares for future
> > support of an ethtool netlink command to select the desired hwtstamp
> > provider. By default, the old API that does not support hwtstamp
> > selectability is used, meaning the hwtstamp provider pointer is unset.
> >
> > Signed-off-by: Kory Maincent <kory.maincent@xxxxxxxxxxx>
>
> I'm getting this error when doing suspend/resume on the Renesas RZ/G3S
> Smarc Module + RZ SMARC Carrier II board:
>
> [ 39.032969] =============================
> [ 39.032983] WARNING: suspicious RCU usage
> [ 39.033000] 6.13.0-rc7-next-20250116-arm64-renesas-00002-g35245dfdc62c
> #7 Not tainted
> [ 39.033019] -----------------------------
> [ 39.033033] drivers/net/phy/phy_device.c:2004 suspicious
> rcu_dereference_protected() usage!
Thanks for the report.
Oh so it seems there are cases where phy_detach is not called under RTNL lock!
This should solve the issue:
- hwprov = rtnl_dereference(dev->hwprov);
+ rcu_read_lock()
+ hwprov = rcu_dereference(dev->hwprov);
/* Disable timestamp if it is the one selected */
if (hwprov && hwprov->phydev == phydev) {
rcu_assign_pointer(dev->hwprov, NULL);
kfree_rcu(hwprov, rcu_head);
}
+ rcu_read_unlock();
I will send a patch soon.
Regards,
--
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
