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The following commit(s) were added to refs/heads/master by this push:
new 0bd1dc58a88 sched/sched_roundrobin.c: fix round-robin scheduling in
SMP mode
0bd1dc58a88 is described below
commit 0bd1dc58a88d7a8423df98686a88b365e09a661d
Author: Filipe Cavalcanti <[email protected]>
AuthorDate: Wed Jan 14 15:50:02 2026 -0300
sched/sched_roundrobin.c: fix round-robin scheduling in SMP mode
In SMP mode, running tasks are in g_assignedtasks[cpu], not the
ready-to-run list, so tcb->flink is NULL. When a round-robin timeslice
expires, checking tcb->flink fails to find the next task.
Fix by calling nxsched_switch_running() directly in SMP mode when the
timeslice expires, which properly finds the next eligible task from the
ready-to-run list.
Signed-off-by: Filipe Cavalcanti <[email protected]>
---
sched/sched/sched_roundrobin.c | 50 ++++++++++++++++++++++++++----------------
1 file changed, 31 insertions(+), 19 deletions(-)
diff --git a/sched/sched/sched_roundrobin.c b/sched/sched/sched_roundrobin.c
index 350777744de..43dc6fcfdf1 100644
--- a/sched/sched/sched_roundrobin.c
+++ b/sched/sched/sched_roundrobin.c
@@ -180,33 +180,45 @@ clock_t nxsched_process_roundrobin(FAR struct tcb_s *tcb,
clock_t ticks,
* give that task a shot.
*/
- if (tcb->flink &&
- tcb->flink->sched_priority >= tcb->sched_priority)
- {
- FAR struct tcb_s *rtcb = this_task();
-
- /* Just resetting the task priority to its current value.
- * This will cause the task to be rescheduled behind any
- * other tasks at the same priority.
- */
+ FAR struct tcb_s *rtcb = this_task();
#ifdef CONFIG_SMP
- DEBUGASSERT(tcb->task_state == TSTATE_TASK_RUNNING);
- if (tcb->cpu != this_cpu())
- {
- nxsched_smp_call_init(&g_call_data,
- nxsched_roundrobin_handler,
- (FAR void *)(uintptr_t)tcb->pid);
- nxsched_smp_call_single_async(tcb->cpu, &g_call_data);
- }
- else if (nxsched_switch_running(tcb->cpu, true))
+ /* In SMP mode, the running task is in g_assignedtasks[cpu], not
+ * in the ready-to-run list. Therefore, tcb->flink is NULL and
+ * we cannot check it to find the next task. If the task is
+ * running on a different CPU, send an SMP call to that CPU.
+ * Otherwise, directly call nxsched_switch_running() to find the
+ * directly call nxsched_switch_running() to find the next eligible
+ * task from the ready-to-run list and switch to it.
+ */
+
+ DEBUGASSERT(tcb->task_state == TSTATE_TASK_RUNNING);
+ if (tcb->cpu != this_cpu())
+ {
+ nxsched_smp_call_init(&g_call_data,
+ nxsched_roundrobin_handler,
+ (FAR void *)(uintptr_t)tcb->pid);
+ nxsched_smp_call_single_async(tcb->cpu, &g_call_data);
+ }
+ else if (nxsched_switch_running(tcb->cpu, true))
+ {
+ up_switch_context(this_task(), rtcb);
+ }
#else
+ /* Just resetting the task priority to its current value.
+ * This will cause the task to be rescheduled behind any
+ * other tasks at the same priority.
+ */
+
+ if (tcb->flink &&
+ tcb->flink->sched_priority >= tcb->sched_priority)
+ {
if (nxsched_reprioritize_rtr(tcb, tcb->sched_priority))
-#endif
{
up_switch_context(this_task(), rtcb);
}
}
+#endif
}
}
else if (tcb->timeslice == 0)
