[PATCH RFC 7/8] rcu: trace CleanupMore condition only if needed

From: Joel Fernandes (Google)
Date: Sun May 13 2018 - 23:16:27 EST


Currently the tree RCU clean up code records a CleanupMore trace event
even if the GP was already in progress. This makes CleanupMore show up
twice for no reason. Avoid it.

Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 8401a253e7de..25c44328d071 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2083,7 +2083,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
rsp->gp_state = RCU_GP_IDLE;
/* Check for GP requests since above loop. */
rdp = this_cpu_ptr(rsp->rda);
- if (ULONG_CMP_LT(rnp->gp_seq, rnp->gp_seq_needed)) {
+ if (!needgp && ULONG_CMP_LT(rnp->gp_seq, rnp->gp_seq_needed)) {
trace_rcu_this_gp(rnp, rdp, rnp->gp_seq_needed,
TPS("CleanupMore"));
needgp = true;
--
2.17.0.441.gb46fe60e1d-goog