Commit 56096ecd authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu-tasks: Disable and enable CPU hotplug in same function 



The rcu_tasks_trace_pregp_step() function invokes cpus_read_lock() to
disable CPU hotplug, and a later call to the rcu_tasks_trace_postscan()
function invokes cpus_read_unlock() to re-enable it.  This was absolutely
necessary in the past in order to protect the intervening scan of the full
tasks list, but there is no longer such a scan.  This commit therefore
improves readability by moving the cpus_read_unlock() call to the end
of the rcu_tasks_trace_pregp_step() function.  This commit is a pure
code-motion commit without any (intended) change in functionality.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
parent e386b672

kernel/rcu/tasks.h

+3 −3
Original line number Diff line number Diff line
@@ -1525,6 +1525,9 @@ static void rcu_tasks_trace_pregp_step(struct list_head *hop) 
		}

		raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);

	}



	// Re-enable CPU hotplug now that the holdout list is populated.

	cpus_read_unlock();

}



/*
@@ -1532,9 +1535,6 @@ static void rcu_tasks_trace_pregp_step(struct list_head *hop) 
 */

static void rcu_tasks_trace_postscan(struct list_head *hop)

{

	// Re-enable CPU hotplug now that the tasklist scan has completed.

	cpus_read_unlock();



	// Wait for late-stage exiting tasks to finish exiting.

	// These might have passed the call to exit_tasks_rcu_finish().

	synchronize_rcu();