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authorVladimir Oltean <vladimir.oltean@nxp.com>2021-10-12 14:40:41 +0300
committerJakub Kicinski <kuba@kernel.org>2021-10-13 03:35:18 +0300
commit49f885b2d97093451410e7279aa29d81e094e108 (patch)
tree3c91c7f55842dfd735b20b62b780eaf7706b08af /security
parentdeab6b1cd9789bb9bd466d5e76aecb8b336259b4 (diff)
downloadlinux-49f885b2d97093451410e7279aa29d81e094e108.tar.xz
net: dsa: tag_ocelot_8021q: break circular dependency with ocelot switch lib
Michael reported that when using the "ocelot-8021q" tagging protocol, the switch driver module must be manually loaded before the tagging protocol can be loaded/is available. This appears to be the same problem described here: https://lore.kernel.org/netdev/20210908220834.d7gmtnwrorhharna@skbuf/ where due to the fact that DSA tagging protocols make use of symbols exported by the switch drivers, circular dependencies appear and this breaks module autoloading. The ocelot_8021q driver needs the ocelot_can_inject() and ocelot_port_inject_frame() functions from the switch library. Previously the wrong approach was taken to solve that dependency: shims were provided for the case where the ocelot switch library was compiled out, but that turns out to be insufficient, because the dependency when the switch lib _is_ compiled is problematic too. We cannot declare ocelot_can_inject() and ocelot_port_inject_frame() as static inline functions, because these access I/O functions like __ocelot_write_ix() which is called by ocelot_write_rix(). Making those static inline basically means exposing the whole guts of the ocelot switch library, not ideal... We already have one tagging protocol driver which calls into the switch driver during xmit but not using any exported symbol: sja1105_defer_xmit. We can do the same thing here: create a kthread worker and one work item per skb, and let the switch driver itself do the register accesses to send the skb, and then consume it. Fixes: 0a6f17c6ae21 ("net: dsa: tag_ocelot_8021q: add support for PTP timestamping") Reported-by: Michael Walle <michael@walle.cc> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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