[Skiboot] [PATCH] cpu: Ensure no-return flag is updated for current cpu_thread

Vaibhav Jain vaibhav at linux.ibm.com
Fri Jul 6 17:09:13 AEST 2018

Presently in case a cpu_thread queues a non returning job on itself,
the variable cpu_thread.job_has_no_return is never updated and other
cpu_threads can still queue a job on it without triggering any

So this patch updates __cpu_queue_job() to ensure that
job_has_no_return is updated on the current cpu_thread before it
branches to the job->func(). So if the current job is non-returning
then other cpu_threads queuing a job on this cpu will trigger a
warning. This should aid in debugging some skiboot deadlocks.

Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
 core/cpu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/core/cpu.c b/core/cpu.c
index a8936fab..84d900d8 100644
--- a/core/cpu.c
+++ b/core/cpu.c
@@ -204,6 +204,8 @@ struct cpu_job *__cpu_queue_job(struct cpu_thread *cpu,
 	/* Can't be scheduled, run it now */
 	if (cpu == NULL) {
+		if (!this_cpu()->job_has_no_return)
+			this_cpu()->job_has_no_return = no_return;
 		job->complete = true;
 		return job;

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