linux-kernel - Re: [PATCH 14/14] rcu: Use lockdep to assert IRQs are disabled/enabled

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Message-Id: <20171021213609.GA2002@linux.vnet.ibm.com>
Date:   Sat, 21 Oct 2017 14:36:09 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "David S . Miller" <davem@...emloft.net>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 14/14] rcu: Use lockdep to assert IRQs are
 disabled/enabled

On Fri, Oct 20, 2017 at 02:56:11AM +0200, Frederic Weisbecker wrote:
> Lockdep now has an integrated IRQs disabled/enabled sanity check. Just
> use it instead of the ad-hoc RCU version.
> 
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

Looks good to me and passes light rcutorture testing.  Feel free to
push this up with the rest of this series.

Acked-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

> ---
>  kernel/rcu/tree.c        | 16 ++++++++--------
>  kernel/rcu/tree_plugin.h | 10 +++++-----
>  2 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index b0ad62b..7661887 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -734,7 +734,7 @@ static int rcu_future_needs_gp(struct rcu_state *rsp)
>  	int idx = (READ_ONCE(rnp->completed) + 1) & 0x1;
>  	int *fp = &rnp->need_future_gp[idx];
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_future_needs_gp() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	return READ_ONCE(*fp);
>  }
> 
> @@ -746,7 +746,7 @@ static int rcu_future_needs_gp(struct rcu_state *rsp)
>  static bool
>  cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
>  {
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "cpu_needs_another_gp() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	if (rcu_gp_in_progress(rsp))
>  		return false;  /* No, a grace period is already in progress. */
>  	if (rcu_future_needs_gp(rsp))
> @@ -773,7 +773,7 @@ static void rcu_eqs_enter_common(bool user)
>  	struct rcu_data *rdp;
>  	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_eqs_enter_common() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
>  	if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
>  	    !user && !is_idle_task(current)) {
> @@ -840,7 +840,7 @@ static void rcu_eqs_enter(bool user)
>   */
>  void rcu_idle_enter(void)
>  {
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_idle_enter() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	rcu_eqs_enter(false);
>  }
> 
> @@ -855,7 +855,7 @@ void rcu_idle_enter(void)
>   */
>  void rcu_user_enter(void)
>  {
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_user_enter() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	rcu_eqs_enter(true);
>  }
>  #endif /* CONFIG_NO_HZ_FULL */
> @@ -880,7 +880,7 @@ void rcu_irq_exit(void)
>  {
>  	struct rcu_dynticks *rdtp;
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	rdtp = this_cpu_ptr(&rcu_dynticks);
> 
>  	/* Page faults can happen in NMI handlers, so check... */
> @@ -947,7 +947,7 @@ static void rcu_eqs_exit(bool user)
>  	struct rcu_dynticks *rdtp;
>  	long long oldval;
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_eqs_exit() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	rdtp = this_cpu_ptr(&rcu_dynticks);
>  	oldval = rdtp->dynticks_nesting;
>  	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
> @@ -1018,7 +1018,7 @@ void rcu_irq_enter(void)
>  	struct rcu_dynticks *rdtp;
>  	long long oldval;
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_enter() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	rdtp = this_cpu_ptr(&rcu_dynticks);
> 
>  	/* Page faults can happen in NMI handlers, so check... */
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index e012b9b..df08e5c 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -325,7 +325,7 @@ static void rcu_preempt_note_context_switch(bool preempt)
>  	struct rcu_data *rdp;
>  	struct rcu_node *rnp;
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_preempt_note_context_switch() invoked with interrupts enabled!!!\n");
> +	lockdep_assert_irqs_disabled();
>  	WARN_ON_ONCE(!preempt && t->rcu_read_lock_nesting > 0);
>  	if (t->rcu_read_lock_nesting > 0 &&
>  	    !t->rcu_read_unlock_special.b.blocked) {
> @@ -1421,7 +1421,7 @@ int rcu_needs_cpu(u64 basemono, u64 *nextevt)
>  	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
>  	unsigned long dj;
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_needs_cpu() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
> 
>  	/* Snapshot to detect later posting of non-lazy callback. */
>  	rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted;
> @@ -1470,7 +1470,7 @@ static void rcu_prepare_for_idle(void)
>  	struct rcu_state *rsp;
>  	int tne;
> 
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_prepare_for_idle() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	if (rcu_is_nocb_cpu(smp_processor_id()))
>  		return;
> 
> @@ -1525,7 +1525,7 @@ static void rcu_prepare_for_idle(void)
>   */
>  static void rcu_cleanup_after_idle(void)
>  {
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_cleanup_after_idle() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	if (rcu_is_nocb_cpu(smp_processor_id()))
>  		return;
>  	if (rcu_try_advance_all_cbs())
> @@ -2012,7 +2012,7 @@ static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_data *my_rdp,
>  						     struct rcu_data *rdp,
>  						     unsigned long flags)
>  {
> -	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_nocb_adopt_orphan_cbs() invoked with irqs enabled!!!");
> +	lockdep_assert_irqs_disabled();
>  	if (!rcu_is_nocb_cpu(smp_processor_id()))
>  		return false; /* Not NOCBs CPU, caller must migrate CBs. */
>  	__call_rcu_nocb_enqueue(my_rdp, rcu_segcblist_head(&rdp->cblist),
> -- 
> 2.7.4
>