From 55911a9f4287c19bf7ef29aeace14044a6ed88cb Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 15 May 2024 14:53:31 +0200 Subject: rcu: Remove full memory barrier on RCU stall printout RCU stall printout fetches the EQS state of a CPU with a preceding full memory barrier. However there is nothing to order this read against at this debugging stage. It is inherently racy when performed remotely. Do a plain read instead. This was the last user of rcu_dynticks_snap(). Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney Reviewed-by: Boqun Feng Reviewed-by: Neeraj Upadhyay --- kernel/rcu/tree_stall.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/rcu/tree_stall.h') diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 460efecd077b..4b0e9d7c4c68 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -501,7 +501,7 @@ static void print_cpu_stall_info(int cpu) } delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq); falsepositive = rcu_is_gp_kthread_starving(NULL) && - rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)); + rcu_dynticks_in_eqs(ct_dynticks_cpu(cpu)); rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j); if (rcuc_starved) // Print signed value, as negative values indicate a probable bug. @@ -515,7 +515,7 @@ static void print_cpu_stall_info(int cpu) rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' : "!."[!delta], ticks_value, ticks_title, - rcu_dynticks_snap(cpu) & 0xffff, + ct_dynticks_cpu(cpu) & 0xffff, ct_dynticks_nesting_cpu(cpu), ct_dynticks_nmi_nesting_cpu(cpu), rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, -- cgit v1.2.3