From: "Paul E. McKenney" <paulmck@kernel.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Uladzislau Rezki <urezki@gmail.com>,
Boqun Feng <boqun.feng@gmail.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
Josh Triplett <josh@joshtriplett.org>,
Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH 2/2] srcu: Early test SRCU polling start
Date: Wed, 14 Apr 2021 08:56:36 -0700 [thread overview]
Message-ID: <20210414155636.GP4510@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <20210414132413.98062-3-frederic@kernel.org>
On Wed, Apr 14, 2021 at 03:24:13PM +0200, Frederic Weisbecker wrote:
> Test an early call to start_poll_synchronize_srcu() and place it before
> the early test to call_srcu() on the same ssp.
>
> After the later call to srcu_barrier(), we expect the first grace period
> completion to be visible by a subsequent call to
> poll_state_synchronize_srcu(). Report otherwise.
>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Given the first patch, this one looks good, give or take my usual
editing compulsion.
Thanx, Paul
> 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 | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
> index dd94a602a6d2..c21b38cc25e9 100644
> --- a/kernel/rcu/update.c
> +++ b/kernel/rcu/update.c
> @@ -524,6 +524,7 @@ static void test_callback(struct rcu_head *r)
> }
>
> DEFINE_STATIC_SRCU(early_srcu);
> +static unsigned long early_srcu_cookie;
>
> struct early_boot_kfree_rcu {
> struct rcu_head rh;
> @@ -536,8 +537,10 @@ 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)) {
> + early_srcu_cookie = start_poll_synchronize_srcu(&early_srcu);
> call_srcu(&early_srcu, &shead, test_callback);
> + }
> rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
> if (!WARN_ON_ONCE(!rhp))
> kfree_rcu(rhp, rh);
> @@ -563,6 +566,7 @@ static int rcu_verify_early_boot_tests(void)
> if (IS_ENABLED(CONFIG_SRCU)) {
> early_boot_test_counter++;
> srcu_barrier(&early_srcu);
> + WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_srcu_cookie));
> }
> }
> if (rcu_self_test_counter != early_boot_test_counter) {
> --
> 2.25.1
>
prev parent reply other threads:[~2021-04-14 15:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-14 13:24 [PATCH 0/2] srcu: Fix early boot hang v3 Frederic Weisbecker
2021-04-14 13:24 ` [PATCH 1/2] srcu: Fix broken node geometry after early ssp init Frederic Weisbecker
2021-04-14 15:55 ` Paul E. McKenney
2021-04-16 23:38 ` Frederic Weisbecker
2021-04-17 13:16 ` Frederic Weisbecker
2021-04-18 4:46 ` Paul E. McKenney
2021-04-19 0:23 ` Frederic Weisbecker
2021-04-19 17:00 ` Paul E. McKenney
2021-04-14 13:24 ` [PATCH 2/2] srcu: Early test SRCU polling start Frederic Weisbecker
2021-04-14 15:56 ` Paul E. McKenney [this message]
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