From: Pingfan Liu <kernelfans@xxxxxxxxx> The state SRCU_SIZE_WAIT_CALL is only used in srcu_gp_start_if_needed(). And it is not needed. Because counter_wrap_check has guarantee that both srcu_gp_seq_needed and srcu_gp_seq_needed_exp are not far behind srcu_gp_seq and no false alarm will be raised by the statement in srcu_gp_start_if_needed() ULONG_CMP_LT(sdp->srcu_gp_seq_needed, s) As a result, once if SRCU_SIZE_WAIT_BARRIER is seen, the tree snp can be used immediately, not need to wait for another srcu_gp_end() to update the srcu_gp_seq_needed and srcu_gp_seq_needed_exp to avoid false alarm. Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx> Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx> Cc: Frederic Weisbecker <frederic@xxxxxxxxxx> Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: "Zhang, Qiang1" <qiang1.zhang@xxxxxxxxx> To: rcu@xxxxxxxxxxxxxxx --- v1 -> v2: rebase onto dev branch kernel/rcu/srcutree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index b25f77df9e5e..b0278d1e9c1f 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1165,7 +1165,7 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp, */ idx = __srcu_read_lock_nmisafe(ssp); ss_state = smp_load_acquire(&ssp->srcu_size_state); - if (ss_state < SRCU_SIZE_WAIT_CALL) + if (ss_state < SRCU_SIZE_WAIT_BARRIER) sdp = per_cpu_ptr(ssp->sda, get_boot_cpu_id()); else sdp = raw_cpu_ptr(ssp->sda); -- 2.31.1
