[PATCH 1/2] rcutorture: Add usage warnings for parameters gp_normal and gp_exp

[lianglihao]

From: Lihao Liang <lianglihao@xxxxxxxxxx>

In rcu_torture_fakewriter(), when param gp_normal is equal to
gp_exp (even when they are false), both cur_ops->sync() and
cur_ops->exp_sync() may be invoked. This commit checks that
if any of them is NULL, it will print out a warning message.
It also emits a warning if gp_normal is true but cur_ops->sync()
is NULL.

Signed-off-by: Lihao Liang <lianglihao@xxxxxxxxxx>
---

I think the last else-if block is redundant and I choose to include it
for completeness. In addition, it may be better to have more informative
warning messages for the new if-else blocks. Feel free to revise them.

 kernel/rcu/rcutorture.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index d1b64dc..d2abebd 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -937,6 +937,16 @@ rcu_torture_writer(void *arg)
 		synctype[nsynctypes++] = RTWS_SYNC;
 	else if (gp_sync && !cur_ops->sync)
 		pr_alert("%s: gp_sync without primitives.\n", __func__);
+	if (gp_normal == gp_exp) {
+		if (!cur_ops->sync)
+			pr_alert("%s: gp_sync without primitives.\n", __func__);
+		if (!cur_ops->exp_sync)
+			pr_alert("%s: gp_exp without primitives.\n", __func__);
+	} else if (gp_normal && !cur_ops->sync) {
+		pr_alert("%s: gp_sync without primitives.\n", __func__);
+	} else if (gp_exp && !cur_ops->exp_sync) {
+		pr_alert("%s: gp_exp without primitives.\n", __func__);
+	}
 	if (WARN_ONCE(nsynctypes == 0,
 		      "rcu_torture_writer: No update-side primitives.\n")) {
 		/*
-- 
2.7.4