From 56096ecd5b04148b6d292e3847c23d4a2a454e94 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 7 Jun 2022 17:25:03 -0700 Subject: [PATCH] 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: Paul E. McKenney Cc: Neeraj Upadhyay Cc: Eric Dumazet Cc: Alexei Starovoitov Cc: Andrii Nakryiko Cc: Martin KaFai Lau Cc: KP Singh --- kernel/rcu/tasks.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index c2aae2643a0b2..bf9cc5bc4ae52 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -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(); -- 2.30.2