[v4,14/14] rcu/tree: Move trace_rcu_callback() before bypassing

Commit Message

Joel Fernandes Aug. 19, 2022, 8:48 p.m. UTC

If any CB is queued into the bypass list, then trace_rcu_callback() does
not show it. This makes it not clear when a callback was actually
queued, as you only end up getting a trace_rcu_invoke_callback() trace.
Fix it by moving trace_rcu_callback() before trace_rcu_nocb_try_bypass().

Signed-off-by: Joel Fernandes (Google) <[e-mail]>
---
 kernel/rcu/tree.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Patch

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 67026382dc21..6e14f0257669 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3101,10 +3101,7 @@  __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy)
 	}
 
 	check_cb_ovld(rdp);
-	if (rcu_nocb_try_bypass(rdp, head, &was_alldone, flags, lazy))
-		return; // Enqueued onto ->nocb_bypass, so just leave.
-	// If no-CBs CPU gets here, rcu_nocb_try_bypass() acquired ->nocb_lock.
-	rcu_segcblist_enqueue(&rdp->cblist, head);
+
 	if (__is_kvfree_rcu_offset((unsigned long)func))
 		trace_rcu_kvfree_callback(rcu_state.name, head,
 					 (unsigned long)func,
@@ -3113,6 +3110,11 @@  __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy)
 		trace_rcu_callback(rcu_state.name, head,
 				   rcu_segcblist_n_cbs(&rdp->cblist));
 
+	if (rcu_nocb_try_bypass(rdp, head, &was_alldone, flags, lazy))
+		return; // Enqueued onto ->nocb_bypass, so just leave.
+	// If no-CBs CPU gets here, rcu_nocb_try_bypass() acquired ->nocb_lock.
+	rcu_segcblist_enqueue(&rdp->cblist, head);
+
 	trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCBQueued"));
 
 	/* Go handle any RCU core processing required. */