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Date:   Fri, 11 Nov 2022 00:04:42 -0800
From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     Zqiang <qiang1.zhang@intel.com>
Cc:     frederic@kernel.org, joel@joelfernandes.org, rcu@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] srcu: Make Tiny SRCU synchronize_srcu() more complete
Message-ID: <20221111080442.GU725751@paulmck-ThinkPad-P17-Gen-1>
Reply-To: paulmck@kernel.org
References: <20221109073638.935473-1-qiang1.zhang@intel.com>
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On Wed, Nov 09, 2022 at 03:36:38PM +0800, Zqiang wrote:
> This commit add lockdep detection for illegal use synchronize_srcu()
> in same-type SRCU (or in RCU) read-side critical section and support
> early boot operations.
> 
> Signed-off-by: Zqiang <qiang1.zhang@intel.com>

Queued and pushed with the usual wordsmithing (please check), thank you!

							Thanx, Paul

> ---
>  kernel/rcu/srcutiny.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
> index 33adafdad261..b12fb0cec44d 100644
> --- a/kernel/rcu/srcutiny.c
> +++ b/kernel/rcu/srcutiny.c
> @@ -197,6 +197,16 @@ void synchronize_srcu(struct srcu_struct *ssp)
>  {
>  	struct rcu_synchronize rs;
>  
> +	RCU_LOCKDEP_WARN(lockdep_is_held(ssp) ||
> +			lock_is_held(&rcu_bh_lock_map) ||
> +			lock_is_held(&rcu_lock_map) ||
> +			lock_is_held(&rcu_sched_lock_map),
> +			"Illegal synchronize_srcu() in same-type SRCU (or in RCU) read-side critical section");
> +
> +	if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE)
> +		return;
> +
> +	might_sleep();
>  	init_rcu_head_on_stack(&rs.head);
>  	init_completion(&rs.completion);
>  	call_srcu(ssp, &rs.head, wakeme_after_rcu);
> -- 
> 2.25.1
>