>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 >--- > 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 1c304fec89c0..fe0759d89c2d 100644 >--- a/kernel/rcu/srcutree.c >+++ b/kernel/rcu/srcutree.c >@@ -1092,7 +1092,7 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp, > check_init_srcu_struct(ssp); > idx = srcu_read_lock(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, 0); Hi Pingfan should it be used get_boot_cpu_id() ? Thanks Zqiang > else > sdp = raw_cpu_ptr(ssp->sda); >-- >2.31.1 >
