Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6cf10081 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Add transitivity to remaining rcu_node ->lock acquisitions 



The rule is that all acquisitions of the rcu_node structure's ->lock
must provide transitivity:  The lock is not acquired that frequently,
and sorting out exactly which required it and which did not would be
a maintenance nightmare.  This commit therefore supplies the needed
transitivity to the remaining ->lock acquisitions.

Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 2a67e741

kernel/rcu/tree.c

+12 −12
Original line number Diff line number Diff line
@@ -1214,7 +1214,7 @@ static void rcu_dump_cpu_stacks(struct rcu_state *rsp) 
	struct rcu_node *rnp;



	rcu_for_each_leaf_node(rsp, rnp) {

		raw_spin_lock_irqsave(&rnp->lock, flags);

		raw_spin_lock_irqsave_rcu_node(rnp, flags);

		if (rnp->qsmask != 0) {

			for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)

				if (rnp->qsmask & (1UL << cpu))
@@ -1237,7 +1237,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum) 


	/* Only let one CPU complain about others per time interval. */



	raw_spin_lock_irqsave(&rnp->lock, flags);

	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	delta = jiffies - READ_ONCE(rsp->jiffies_stall);

	if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {

		raw_spin_unlock_irqrestore(&rnp->lock, flags);
@@ -1256,7 +1256,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum) 
	       rsp->name);

	print_cpu_stall_info_begin();

	rcu_for_each_leaf_node(rsp, rnp) {

		raw_spin_lock_irqsave(&rnp->lock, flags);

		raw_spin_lock_irqsave_rcu_node(rnp, flags);

		ndetected += rcu_print_task_stall(rnp);

		if (rnp->qsmask != 0) {

			for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
@@ -1327,7 +1327,7 @@ static void print_cpu_stall(struct rcu_state *rsp) 


	rcu_dump_cpu_stacks(rsp);



	raw_spin_lock_irqsave(&rnp->lock, flags);

	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	if (ULONG_CMP_GE(jiffies, READ_ONCE(rsp->jiffies_stall)))

		WRITE_ONCE(rsp->jiffies_stall,

			   jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
@@ -2897,7 +2897,7 @@ __rcu_process_callbacks(struct rcu_state *rsp) 
	/* Does this CPU require a not-yet-started grace period? */

	local_irq_save(flags);

	if (cpu_needs_another_gp(rsp, rdp)) {

		raw_spin_lock(&rcu_get_root(rsp)->lock); /* irqs disabled. */

		raw_spin_lock_rcu_node(rcu_get_root(rsp)); /* irqs disabled. */

		needwake = rcu_start_gp(rsp);

		raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);

		if (needwake)
@@ -3718,7 +3718,7 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp, 
				mask_ofl_ipi &= ~mask;

			} else {

				/* Failed, raced with offline. */

				raw_spin_lock_irqsave(&rnp->lock, flags);

				raw_spin_lock_irqsave_rcu_node(rnp, flags);

				if (cpu_online(cpu) &&

				    (rnp->expmask & mask)) {

					raw_spin_unlock_irqrestore(&rnp->lock,
@@ -3727,7 +3727,7 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp, 
					if (cpu_online(cpu) &&

					    (rnp->expmask & mask))

						goto retry_ipi;

					raw_spin_lock_irqsave(&rnp->lock,

					raw_spin_lock_irqsave_rcu_node(rnp,

								       flags);

				}

				if (!(rnp->expmask & mask))
@@ -4110,7 +4110,7 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf) 
		rnp = rnp->parent;

		if (rnp == NULL)

			return;

		raw_spin_lock(&rnp->lock); /* Interrupts already disabled. */

		raw_spin_lock_rcu_node(rnp); /* Interrupts already disabled. */

		rnp->qsmaskinit |= mask;

		raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */

	}
@@ -4127,7 +4127,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) 
	struct rcu_node *rnp = rcu_get_root(rsp);



	/* Set up local state, ensuring consistent view of global state. */

	raw_spin_lock_irqsave(&rnp->lock, flags);

	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);

	rdp->dynticks = &per_cpu(rcu_dynticks, cpu);

	WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
@@ -4154,7 +4154,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp) 
	struct rcu_node *rnp = rcu_get_root(rsp);



	/* Set up local state, ensuring consistent view of global state. */

	raw_spin_lock_irqsave(&rnp->lock, flags);

	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	rdp->qlen_last_fqs_check = 0;

	rdp->n_force_qs_snap = rsp->n_force_qs;

	rdp->blimit = blimit;
@@ -4301,7 +4301,7 @@ static int __init rcu_spawn_gp_kthread(void) 
		t = kthread_create(rcu_gp_kthread, rsp, "%s", rsp->name);

		BUG_ON(IS_ERR(t));

		rnp = rcu_get_root(rsp);

		raw_spin_lock_irqsave(&rnp->lock, flags);

		raw_spin_lock_irqsave_rcu_node(rnp, flags);

		rsp->gp_kthread = t;

		if (kthread_prio) {

			sp.sched_priority = kthread_prio;

kernel/rcu/tree_plugin.h

+1 −1
Original line number Diff line number Diff line
@@ -525,7 +525,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) 
	unsigned long flags;

	struct task_struct *t;



	raw_spin_lock_irqsave(&rnp->lock, flags);

	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	if (!rcu_preempt_blocked_readers_cgp(rnp)) {

		raw_spin_unlock_irqrestore(&rnp->lock, flags);

		return;

kernel/rcu/tree_trace.c

+1 −1
Original line number Diff line number Diff line
@@ -319,7 +319,7 @@ static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp) 
	unsigned long gpmax;

	struct rcu_node *rnp = &rsp->node[0];



	raw_spin_lock_irqsave(&rnp->lock, flags);

	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	completed = READ_ONCE(rsp->completed);

	gpnum = READ_ONCE(rsp->gpnum);

	if (completed == gpnum)