On Tue, Feb 23, 2021 at 01:10:09AM +0100, Frederic Weisbecker wrote:
No need to disarm the nocb_timer if rcu_nocb is polling because it shouldn't be armed either.
Signed-off-by: Frederic Weisbecker frederic@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
OK, so it does make sense to move that del_timer() under the following "if" statement, then. ;-)
kernel/rcu/tree_plugin.h | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 9da67b0d3997..d8b50ff40e4b 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2186,18 +2186,18 @@ static void nocb_gp_wait(struct rcu_data *my_rdp) my_rdp->nocb_gp_gp = needwait_gp; my_rdp->nocb_gp_seq = needwait_gp ? wait_gp_seq : 0; if (bypass) {
raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);// Avoid race with first bypass CB.if (my_rdp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);del_timer(&my_rdp->nocb_timer);}
raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);// Avoid race with first bypass CB.if (my_rdp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);del_timer(&my_rdp->nocb_timer);} // At least one child with non-empty ->nocb_bypass, so set // timer in order to avoid stranding its callbacks. mod_timer(&my_rdp->nocb_bypass_timer, j + 2);raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);-- 2.25.1