rcu: Fix missing task information during rcu-preempt stall

The first item list_for_each_entry_continue(alist) iterates over is alist->next, rather than alist itself. Consequently, rcu_print_detail_task_stall_rnp() skips the task referenced by gp_tasks.

Use gp_tasks->prev as the argument to list_for_each_entry_continue() instead.

Signed-off-by Patrick Daly <[email protected]>

---
 kernel/rcu/tree_plugin.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

kernel/rcu/tree_plugin.h +2 -2

index d1dda52..9fbecdc 100644
@@ -459,7 +459,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
 		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		return;
 	}
-	t = list_entry(rnp->gp_tasks,
+	t = list_entry(rnp->gp_tasks->prev,
 		       struct task_struct, rcu_node_entry);
 	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry)
 		sched_show_task(t);

@@ -524,7 +524,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp)
 	if (!rcu_preempt_blocked_readers_cgp(rnp))
 		return 0;
 	rcu_print_task_stall_begin(rnp);
-	t = list_entry(rnp->gp_tasks,
+	t = list_entry(rnp->gp_tasks->prev,
 		       struct task_struct, rcu_node_entry);
 	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) {
 		printk(KERN_CONT " P%d", t->pid);

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project