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Commit c0b334c5 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Add lockdep_assert_held() teeth to tree.c 



Comments can be helpful, but assertions carry more force.  This
commit therefore adds lockdep_assert_held() and RCU_LOCKDEP_WARN()
calls to enforce lock-held and interrupt-disabled preconditions.

Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 0c8e0e3c

kernel/rcu/tree.c

+25 −0
Original line number Diff line number Diff line
@@ -762,6 +762,7 @@ 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!!!");

	return READ_ONCE(*fp);

}
@@ -773,6 +774,7 @@ 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!!!");

	if (rcu_gp_in_progress(rsp))

		return false;  /* No, a grace period is already in progress. */

	if (rcu_future_needs_gp(rsp))
@@ -799,6 +801,7 @@ 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!!!");

	trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);

	if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&

	    !user && !is_idle_task(current)) {
@@ -972,6 +975,7 @@ 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!!!");

	rdtp = this_cpu_ptr(&rcu_dynticks);

	oldval = rdtp->dynticks_nesting;

	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
@@ -1679,6 +1683,8 @@ void rcu_cpu_stall_reset(void) 
static unsigned long rcu_cbs_completed(struct rcu_state *rsp,

				       struct rcu_node *rnp)

{

	lockdep_assert_held(&rnp->lock);



	/*

	 * If RCU is idle, we just wait for the next grace period.

	 * But we can only be sure that RCU is idle if we are looking
@@ -1724,6 +1730,8 @@ rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp, 
	bool ret = false;

	struct rcu_node *rnp_root = rcu_get_root(rdp->rsp);



	lockdep_assert_held(&rnp->lock);



	/*

	 * Pick up grace-period number for new callbacks.  If this

	 * grace period is already marked as needed, return to the caller.
@@ -1850,6 +1858,8 @@ static bool rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp, 
{

	bool ret = false;



	lockdep_assert_held(&rnp->lock);



	/* If no pending (not yet ready to invoke) callbacks, nothing to do. */

	if (!rcu_segcblist_pend_cbs(&rdp->cblist))

		return false;
@@ -1888,6 +1898,8 @@ static bool rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp, 
static bool rcu_advance_cbs(struct rcu_state *rsp, struct rcu_node *rnp,

			    struct rcu_data *rdp)

{

	lockdep_assert_held(&rnp->lock);



	/* If no pending (not yet ready to invoke) callbacks, nothing to do. */

	if (!rcu_segcblist_pend_cbs(&rdp->cblist))

		return false;
@@ -1914,6 +1926,8 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp, 
	bool ret;

	bool need_gp;



	lockdep_assert_held(&rnp->lock);



	/* Handle the ends of any preceding grace periods first. */

	if (rdp->completed == rnp->completed &&

	    !unlikely(READ_ONCE(rdp->gpwrap))) {
@@ -2346,6 +2360,7 @@ static bool 
rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,

		      struct rcu_data *rdp)

{

	lockdep_assert_held(&rnp->lock);

	if (!rsp->gp_kthread || !cpu_needs_another_gp(rsp, rdp)) {

		/*

		 * Either we have not yet spawned the grace-period
@@ -2407,6 +2422,7 @@ static bool rcu_start_gp(struct rcu_state *rsp) 
static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)

	__releases(rcu_get_root(rsp)->lock)

{

	lockdep_assert_held(&rcu_get_root(rsp)->lock);

	WARN_ON_ONCE(!rcu_gp_in_progress(rsp));

	WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);

	raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);
@@ -2431,6 +2447,8 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, 
	unsigned long oldmask = 0;

	struct rcu_node *rnp_c;



	lockdep_assert_held(&rnp->lock);



	/* Walk up the rcu_node hierarchy. */

	for (;;) {

		if (!(rnp->qsmask & mask) || rnp->gpnum != gps) {
@@ -2491,6 +2509,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_state *rsp, 
	unsigned long mask;

	struct rcu_node *rnp_p;



	lockdep_assert_held(&rnp->lock);

	if (rcu_state_p == &rcu_sched_state || rsp != rcu_state_p ||

	    rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {

		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
@@ -2604,6 +2623,8 @@ static void 
rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,

			  struct rcu_node *rnp, struct rcu_data *rdp)

{

	lockdep_assert_held(&rsp->orphan_lock);



	/* No-CBs CPUs do not have orphanable callbacks. */

	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) || rcu_is_nocb_cpu(rdp->cpu))

		return;
@@ -2644,6 +2665,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags) 
{

	struct rcu_data *rdp = raw_cpu_ptr(rsp->rda);



	lockdep_assert_held(&rsp->orphan_lock);



	/* No-CBs CPUs are handled specially. */

	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) ||

	    rcu_nocb_adopt_orphan_cbs(rsp, rdp, flags))
@@ -2710,6 +2733,7 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf) 
	long mask;

	struct rcu_node *rnp = rnp_leaf;



	lockdep_assert_held(&rnp->lock);

	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) ||

	    rnp->qsmaskinit || rcu_preempt_has_tasks(rnp))

		return;
@@ -3703,6 +3727,7 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf) 
	long mask;

	struct rcu_node *rnp = rnp_leaf;



	lockdep_assert_held(&rnp->lock);

	for (;;) {

		mask = rnp->grpmask;

		rnp = rnp->parent;