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As reported by Sebastian Andrzej Siewior the use of local_bh_disable() is only feasible in uni processor systems to update the modification rules. The usual use-case to update the modification rules is to update the data of the modifications but not the modification types (AND/OR/XOR/SET) or the checksum functions itself. To omit additional memory allocations to maintain fast modification switching times, the modification description space is doubled at gw-job creation time so that only the reference to the active modification description is changed under rcu protection. Rename cgw_job::mod to cf_mod and make it a RCU pointer. Allocate in cgw_create_job() and free it together with cgw_job in cgw_job_free_rcu(). Update all users to dereference cgw_job::cf_mod with a RCU accessor and if possible once. [bigeasy: Replace mod1/mod2 from the Oliver's original patch with dynamic allocation, use RCU annotation and accessor] Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Closes: https://lore.kernel.org/linux-can/20231031112349.y0aLoBrz@linutronix.de/ Fixes: dd895d7f21b2 ("can: cangw: introduce optional uid to reference created routing jobs") Tested-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://patch.msgid.link/20250429070555.cs-7b_eZ@linutronix.de Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>