[Crash-utility] [PATCH] Use only tasks on online CPUs for bt -a

[Michael Holzheu]

Hello Dave,

Currently for "bt -a" also swapper tasks on offline CPUs are printed
(at least on s390). Wouldn't it be better to only print a backtrace,
when the task is running on an online CPU?

My suggestion would be to implement that with the following patch
by only setting the panic threads for online CPUs. I also attached a
second alternative patch that fills the active set array only with
tasks on online CPUs.

What do you think?

Michael
---
 task.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/task.c
+++ b/task.c
@@ -5658,8 +5658,12 @@ populate_panic_threads(void)
         struct task_context *tc;
 
 	if (get_active_set()) {
-		for (i = 0; i < NR_CPUS; i++) 
-			tt->panic_threads[i] = tt->active_set[i];
+		for (i = 0; i < NR_CPUS; i++) {
+			if (kt->cpu_flags[i] & ONLINE)
+				tt->panic_threads[i] = tt->active_set[i];
+			else
+				tt->panic_threads[i] = 0;
+		}
 		return;
 	}
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