Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH rcu 29/32] rcu-tasks: Disable and enable CPU hotplug in same function | Date | Mon, 20 Jun 2022 15:54:08 -0700 |
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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 <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> --- 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(); -- 2.31.1.189.g2e36527f23
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