Arguments

Description

Control will return to the caller some time after a full rcu-sched grace period has elapsed, in other words after all currently executing rcu-sched read-side critical sections have completed. These read-side critical sections are delimited by rcu_read_lock_sched and rcu_read_unlock_sched, and may be nested. Note that preempt_disable, local_irq_disable, and so on may be used in place of rcu_read_lock_sched.

This means that all preempt_disable code sequences, including NMI and hardware-interrupt handlers, in progress on entry will have completed before this primitive returns. However, this does not guarantee that softirq handlers will have completed, since in some kernels, these handlers can run in process context, and can block.

This primitive provides the guarantees made by the (now removed) synchronize_kernel API. In contrast, synchronize_rcu only guarantees that rcu_read_lock sections will have completed. In “classic RCU”, these two guarantees happen to be one and the same, but can differ in realtime RCU implementations.