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rcu: Add WARN_ON_ONCE() consistency checks covering state transitions

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o Verify that qsmask bits stay clear through GP
  initialization.

o Verify that cpu_quiet_msk_finish() is never invoked unless
  there actually is an RCU grace period in progress.

o Verify that all internal-node rcu_node structures have empty
  blocked_tasks[] lists.

o Verify that child rcu_node structure's bits remain clear after
  acquiring parent's lock.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
LKML-Reference: <12532926191947-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney
2009-09-18 09:50:17 -07:00
committed by Ingo Molnar
parent 16e3081191
commit 28ecd58020
2 changed files with 23 additions and 10 deletions
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20
kernel/rcutree_plugin.h
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@@ -206,7 +206,8 @@ static void rcu_read_unlock_special(struct task_struct *t)
*/
if (!empty && rnp->qsmask == 0 &&
list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1])) {
t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
struct rcu_node *rnp_p;
if (rnp->parent == NULL) {
/* Only one rcu_node in the tree. */
cpu_quiet_msk_finish(&rcu_preempt_state, flags);
@@ -215,9 +216,10 @@ static void rcu_read_unlock_special(struct task_struct *t)
/* Report up the rest of the hierarchy. */
mask = rnp->grpmask;
spin_unlock_irqrestore(&rnp->lock, flags);
rnp = rnp->parent;
spin_lock_irqsave(&rnp->lock, flags);
cpu_quiet_msk(mask, &rcu_preempt_state, rnp, flags);
rnp_p = rnp->parent;
spin_lock_irqsave(&rnp_p->lock, flags);
WARN_ON_ONCE(rnp->qsmask);
cpu_quiet_msk(mask, &rcu_preempt_state, rnp_p, flags);
return;
}
spin_unlock(&rnp->lock);
@@ -278,6 +280,7 @@ static void rcu_print_task_stall(struct rcu_node *rnp)
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
{
WARN_ON_ONCE(!list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]));
WARN_ON_ONCE(rnp->qsmask);
}
/*
@@ -302,7 +305,8 @@ static int rcu_preempted_readers(struct rcu_node *rnp)
* The caller must hold rnp->lock with irqs disabled.
*/
static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
struct rcu_node *rnp)
struct rcu_node *rnp,
struct rcu_data *rdp)
{
int i;
struct list_head *lp;
@@ -314,6 +318,9 @@ static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
WARN_ONCE(1, "Last CPU thought to be offlined?");
return; /* Shouldn't happen: at least one CPU online. */
}
WARN_ON_ONCE(rnp != rdp->mynode &&
(!list_empty(&rnp->blocked_tasks[0]) ||
!list_empty(&rnp->blocked_tasks[1])));
/*
* Move tasks up to root rcu_node. Rely on the fact that the
@@ -489,7 +496,8 @@ static int rcu_preempted_readers(struct rcu_node *rnp)
* tasks that were blocked within RCU read-side critical sections.
*/
static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
struct rcu_node *rnp)
struct rcu_node *rnp,
struct rcu_data *rdp)
{
}