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Subject[PATCH 5/5] srcu: Early test SRCU polling start
Date
Test early calls to start_poll_synchronize_srcu(), mixed within the
early test to call_srcu(), and make sure that
poll_state_synchronize_srcu() correctly see the expired grace periods
after the srcu_barrier() on late initcall. Normally srcu_barrier()
doesn't wait for callback-less grace periods but early calls to
start_poll_synchronize_srcu() involve empty callbacks.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
---
kernel/rcu/update.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index dd94a602a6d2..7ee57d66a327 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -528,6 +528,7 @@ DEFINE_STATIC_SRCU(early_srcu);
struct early_boot_kfree_rcu {
struct rcu_head rh;
};
+static unsigned long early_cookie[3];

static void early_boot_test_call_rcu(void)
{
@@ -536,8 +537,14 @@ static void early_boot_test_call_rcu(void)
struct early_boot_kfree_rcu *rhp;

call_rcu(&head, test_callback);
- if (IS_ENABLED(CONFIG_SRCU))
+ if (IS_ENABLED(CONFIG_SRCU)) {
+ int i;
+ early_cookie[0] = start_poll_synchronize_srcu(&early_srcu);
call_srcu(&early_srcu, &shead, test_callback);
+
+ for (i = 1; i < ARRAY_SIZE(early_cookie); i++)
+ early_cookie[i] = start_poll_synchronize_srcu(&early_srcu);
+ }
rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
if (!WARN_ON_ONCE(!rhp))
kfree_rcu(rhp, rh);
@@ -561,8 +568,11 @@ static int rcu_verify_early_boot_tests(void)
early_boot_test_counter++;
rcu_barrier();
if (IS_ENABLED(CONFIG_SRCU)) {
+ int i;
early_boot_test_counter++;
srcu_barrier(&early_srcu);
+ for (i = 0; i < ARRAY_SIZE(early_cookie); i++)
+ WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_cookie[i]));
}
}
if (rcu_self_test_counter != early_boot_test_counter) {
--
2.25.1
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