[Crash-utility] [PATCH 1/1] CFS runqueue loop detection

[Dave Anderson]

----- Original Message -----
> Here is a patch against crash v6.0.2 that adds duplicate node detection
> per-CPU for the CFS runqueue display in dump_CFS_runqueues() for the
> runq command.
> 
> This resolves the failure to bail-out of the unending looping display I
> get with the crash dump I have that has a corrupted CFS runqueue
> containing a loop.
> 
> Signed-off-by: David Mair <dmair at suse.com>
> ---

That was quick! 

I'm going to have to re-work this patch slightly because of the queued
changes for crash-6.0.3 that are based upon Daisuke's runq patch:

  [Crash-utility] [PATCH] runq: search current task's runqueue explicitly
  https://www.redhat.com/archives/crash-utility/2012-January/msg00009.html

I'm going to try to get a release out in the next day or two.

Thanks,
  Dave


> 
>  task.c |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/task.c b/task.c
> index 433a043..0333fe8 100755
> --- a/task.c
> +++ b/task.c
> @@ -7050,7 +7050,12 @@ dump_tasks_in_cfs_rq(ulong cfs_rq, ulong skip)
>  				     OFFSET(sched_entity_run_node));
>  		if (!tc)
>  			continue;
> -		dump_task_runq_entry(tc);
> +		if (hq_enter((ulong)tc)) {
> +			dump_task_runq_entry(tc);
> +		} else {
> +			error(WARNING, "Duplicate CFS runqueue node, task %lx, probable
> loop\n", tc->task);
> +			return total;
> +		}
>  		total++;
>  	}
> 
> @@ -7217,10 +7222,12 @@ dump_CFS_runqueues(void)
>  		fprintf(fp, "  CFS RB_ROOT: %lx\n", (ulong)root);
> 
>  		tot = 0;
> +		hq_open();
>  		if (curr_cfs_rq)
>  			tot += dump_tasks_in_cfs_rq(curr_cfs_rq, 0);
>  		if (cfs_rq != curr_cfs_rq)
>  			tot += dump_tasks_in_cfs_rq(cfs_rq, curr_cfs_rq);
> +		hq_close();
>  		if (!tot) {
>  			INDENT(5);
>  			fprintf(fp, "[no tasks queued]\n");
> 
> --
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