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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: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2017-04-28 12:32:15 -07:00
parent 0c8e0e3c37
commit c0b334c5bf
1 changed files with 25 additions and 0 deletions
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25
kernel/rcu/tree.c
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@ -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;