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SubjectRe: [PATCH] rcu: Fix missing task information during rcu-preempt stall
On Tue, Apr 07, 2015 at 01:03:13PM -0700, Patrick Daly wrote:
> 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.

Good catch, thank you!

Queued for v4.2.

Thanx, Paul

> Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
> ---
> kernel/rcu/tree_plugin.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index d1dda52..9fbecdc 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -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);
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>



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