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| author | Joel Fernandes <joelagnelf@nvidia.com> | 2025-07-15 16:01:54 -0400 |
|---|---|---|
| committer | Neeraj Upadhyay <neeraj.iitr10@gmail.com> | 2025-07-22 17:10:31 +0530 |
| commit | 186779c036468038b0d077ec5333a51512f867e5 (patch) | |
| tree | a7cd463c843631cf2bdfe72e169316ee89869724 /kernel/rcu/tree.c | |
| parent | 30a7806adab5f6b971cf07439ed6a3fac3fd80cf (diff) | |
rcu: Document separation of rcu_state and rnp's gp_seq
The details of this are subtle and was discussed recently. Add a
quick-quiz about this and refer to it from the code, for more clarity.
Reviewed-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 384af6b5cf9c..b206db119546 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1845,6 +1845,10 @@ static noinline_for_stack bool rcu_gp_init(void) * use-after-free errors. For a detailed explanation of this race, see * Documentation/RCU/Design/Requirements/Requirements.rst in the * "Hotplug CPU" section. + * + * Also note that the root rnp's gp_seq is kept separate from, and lags, + * the rcu_state's gp_seq, for a reason. See the Quick-Quiz on + * Single-node systems for more details (in Data-Structures.rst). */ rcu_seq_start(&rcu_state.gp_seq); /* Ensure that rcu_seq_done_exact() guardband doesn't give false positives. */ |