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rcu: Add assertions verifying blocked-tasks list

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This commit adds assertions verifying the consistency of the rcu_node
structure's ->blkd_tasks list and its ->gp_tasks, ->exp_tasks, and
->boost_tasks pointers.  In particular, the ->blkd_tasks lists must be
empty except for leaf rcu_node structures.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2017-07-11 21:52:31 -07:00
parent 35fe723bda
commit 2dee9404fa
2 changed files with 11 additions and 2 deletions
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2
kernel/rcu/tree.c
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@ -2410,6 +2410,8 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
return;
}
WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */
WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1 &&
rcu_preempt_blocked_readers_cgp(rnp));
rnp->qsmask &= ~mask;
trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum,
mask, rnp->qsmask, rnp->level,

11
kernel/rcu/tree_plugin.h
View File

@ -180,6 +180,8 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
struct task_struct *t = current;
lockdep_assert_held(&rnp->lock);
WARN_ON_ONCE(rdp->mynode != rnp);
WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1);
/*
* Decide where to queue the newly blocked task. In theory,
@ -261,6 +263,10 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
rnp->gp_tasks = &t->rcu_node_entry;
if (!rnp->exp_tasks && (blkd_state & RCU_EXP_BLKD))
rnp->exp_tasks = &t->rcu_node_entry;
WARN_ON_ONCE(!(blkd_state & RCU_GP_BLKD) !=
!(rnp->qsmask & rdp->grpmask));
WARN_ON_ONCE(!(blkd_state & RCU_EXP_BLKD) !=
!(rnp->expmask & rdp->grpmask));
raw_spin_unlock_rcu_node(rnp); /* interrupts remain disabled. */
/*
@ -482,6 +488,7 @@ void rcu_read_unlock_special(struct task_struct *t)
rnp = t->rcu_blocked_node;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
WARN_ON_ONCE(rnp != t->rcu_blocked_node);
WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1);
empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);
empty_exp = sync_rcu_preempt_exp_done(rnp);
smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */
@ -495,10 +502,10 @@ void rcu_read_unlock_special(struct task_struct *t)
if (&t->rcu_node_entry == rnp->exp_tasks)
rnp->exp_tasks = np;
if (IS_ENABLED(CONFIG_RCU_BOOST)) {
if (&t->rcu_node_entry == rnp->boost_tasks)
rnp->boost_tasks = np;
/* Snapshot ->boost_mtx ownership w/rnp->lock held. */
drop_boost_mutex = rt_mutex_owner(&rnp->boost_mtx) == t;
if (&t->rcu_node_entry == rnp->boost_tasks)
rnp->boost_tasks = np;
}
/*