What is the difference between rcuc and rcub Kernal threads?
I know that rcu (Read-Copy_Update) is a synchronization mechanism that manages reads and updates simultaneously. https://en.wikipedia.org/wiki/Read-copy-update
And I understand that there are thress main usages for the mechanism:
a. rcu_read_lock() / rcu_read_unlock() rcu_dereference()
b. rcu_read_lock_bh() / rcu_read_unlock_bh() local_bh_disable() / local_bh_enable() rcu_dereference_bh()
c. rcu_read_lock_sched() / rcu_read_unlock_sched() preempt_disable() / preempt_enable() local_irq_save() / local_irq_restore() hardirq enter / hardirq exit NMI enter / NMI exit rcu_dereference_sched()
According to : Blockquotehttps://www.kernel.org/doc/Documentation/RCU/whatisRCU.txt
Yet I didn't find information about rcu{c,b} & when each of these is used, and what "c" and "b" stands for?