Vladimir Oltean
2022-Mar-10 15:07 UTC
[Bridge] [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation
On Thu, Mar 10, 2022 at 04:00:52PM +0100, Hans Schultz wrote:> >> + brport = dsa_port_to_bridge_port(dp); > > > > Since this is threaded interrupt context, I suppose it could race with > > dsa_port_bridge_leave(). So it is best to check whether "brport" is NULL > > or not. > > > Would something like: > if (dsa_is_unused_port(chip->ds, port)) > return -ENODATA; > > be appropriate and sufficient for that?static inline struct net_device *dsa_port_to_bridge_port(const struct dsa_port *dp) { if (!dp->bridge) return NULL; if (dp->lag) return dp->lag->dev; else if (dp->hsr_dev) return dp->hsr_dev; return dp->slave; } Notice the "dp->bridge" check. The assignments are in dsa_port_bridge_create() and in dsa_port_bridge_destroy(). These functions assume rtnl_mutex protection. The question was how do you serialize with that, and why do you assume that dsa_port_to_bridge_port() returns non-NULL. So no, dsa_is_unused_port() would do absolutely nothing to help.
Hans Schultz
2022-Mar-10 15:51 UTC
[Bridge] [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation
On tor, mar 10, 2022 at 17:07, Vladimir Oltean <olteanv at gmail.com> wrote:> On Thu, Mar 10, 2022 at 04:00:52PM +0100, Hans Schultz wrote: >> >> + brport = dsa_port_to_bridge_port(dp); >> > >> > Since this is threaded interrupt context, I suppose it could race with >> > dsa_port_bridge_leave(). So it is best to check whether "brport" is NULL >> > or not. >> > >> Would something like: >> if (dsa_is_unused_port(chip->ds, port)) >> return -ENODATA; >> >> be appropriate and sufficient for that? > > static inline > struct net_device *dsa_port_to_bridge_port(const struct dsa_port *dp) > { > if (!dp->bridge) > return NULL; > > if (dp->lag) > return dp->lag->dev; > else if (dp->hsr_dev) > return dp->hsr_dev; > > return dp->slave; > } > > Notice the "dp->bridge" check. The assignments are in dsa_port_bridge_create() > and in dsa_port_bridge_destroy(). These functions assume rtnl_mutex protection. > The question was how do you serialize with that, and why do you assume > that dsa_port_to_bridge_port() returns non-NULL. > > So no, dsa_is_unused_port() would do absolutely nothing to help.I was thinking in indirect terms (dangerous I know :-). But wrt the nl lock, I wonder when other threads could pull the carpet away under this, and so I might have to wait till after the last call (mv88e6xxx_g1_atu_loadpurge) to free the nl lock?