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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-05-16 18:00:17 -0700 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-07-12 15:39:16 -0700 |
commit | c7037ff5249cee237b8c8a6f99998ae4f3916b60 (patch) | |
tree | 91011ef383bcb9b58d5d1b9522a7117ce48d3023 /kernel/rcu | |
parent | 3b57a3994f330a102b91bd70c84c9530c0ae50f6 (diff) | |
download | op-kernel-dev-c7037ff5249cee237b8c8a6f99998ae4f3916b60.zip op-kernel-dev-c7037ff5249cee237b8c8a6f99998ae4f3916b60.tar.gz |
rcu: Clarify and correct the rcu_preempt_qs() header comment
The rcu_preempt_qs() function only applies to the CPU, not the task.
A task really is allowed to invoke this function while in an RCU-preempt
read-side critical section, but only if it has first added itself to
some leaf rcu_node structure's ->blkd_tasks list.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r-- | kernel/rcu/tree_plugin.h | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 0239cf8..07d1ad1 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -294,13 +294,17 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp) } /* - * Record a preemptible-RCU quiescent state for the specified CPU. Note - * that this just means that the task currently running on the CPU is - * not in a quiescent state. There might be any number of tasks blocked - * while in an RCU read-side critical section. + * Record a preemptible-RCU quiescent state for the specified CPU. + * Note that this does not necessarily mean that the task currently running + * on the CPU is in a quiescent state: Instead, it means that the current + * grace period need not wait on any RCU read-side critical section that + * starts later on this CPU. It also means that if the current task is + * in an RCU read-side critical section, it has already added itself to + * some leaf rcu_node structure's ->blkd_tasks list. In addition to the + * current task, there might be any number of other tasks blocked while + * in an RCU read-side critical section. * - * As with the other rcu_*_qs() functions, callers to this function - * must disable preemption. + * Callers to this function must disable preemption. */ static void rcu_preempt_qs(void) { |