| Message ID | 20210223001011.127063-9-frederic@kernel.org |
|---|---|
| State | Accepted |
| Commit | 552cac80e65f38a0cc9022456c09efed7e88f9d6 |
| Headers | show |
| Series | rcu/nocb updates v2 | expand |
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c80b214a86bb..0fdf0223f08f 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2500,10 +2500,6 @@ int rcu_nocb_cpu_deoffload(int cpu) struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); int ret = 0; - if (rdp == rdp->nocb_gp_rdp) { - pr_info("Can't deoffload an rdp GP leader (yet)\n"); - return -EINVAL; - } mutex_lock(&rcu_state.barrier_mutex); cpus_read_lock(); if (rcu_rdp_is_offloaded(rdp)) {
The only thing that prevented an rdp leader from being de-offloaded was the nocb_bypass_timer that used to lock the nocb_lock of the rdp leader. If an rdp gets de-offloaded, it will subtely ignore rcu_nocb_lock() calls and do its job in the timer unsafely. Worse yet: if it gets re-offloaded in the middle of the timer, rcu_nocb_unlock() would try to unlock, leaving it imbalanced. Now that the nocb_bypass_timer doesn't use the nocb_lock anymore, we can safely allow rdp leader to be de-offloaded. Reported-by: Paul E. McKenney <paulmck@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> --- kernel/rcu/tree_plugin.h | 4 ---- 1 file changed, 4 deletions(-)