kernel/idle: Fix !SCHED_IPI_SUPPORTED (0ca7150f) · Commits · Wenxi XU / zephyr

The requirement for k_yield() to handle "yielding" in the idle thread was removed a while back, but it missed a spot where we'd try to yield in the fallback loop on bringup platforms that lack an IPI. This now crashes, because yield now unconditionally tries to reschedule the current thread, which doesn't work for idle threads that don't live in the run queue. Just make it a busy loop calling swap(), even simpler. Fixes #50119 Signed-off-by:

Andy Ross <andyross@google.com>

kernel/idle.c

+10 −10

Original line number	Diff line number	Diff line
		@@ -39,19 +39,19 @@ void idle(void unused1, void unused2, void *unused3)
		__ASSERT_NO_MSG(_current->base.prio >= 0);

		while (true) {
		/* SMP systems without a working IPI can't
		* actual enter an idle state, because they
		* can't be notified of scheduler changes
		* (i.e. threads they should run). They just
		* spin in a yield loop. This is intended as
		* a fallback configuration for new platform
		* bringup.
		/* SMP systems without a working IPI can't actual
		* enter an idle state, because they can't be notified
		* of scheduler changes (i.e. threads they should
		* run). They just spin instead, with a minimal
		* relaxation loop to prevent hammering the scheduler
		* lock and/or timer driver. This is intended as a
		* fallback configuration for new platform bringup.
		*/
		if (IS_ENABLED(CONFIG_SMP) &&
		!IS_ENABLED(CONFIG_SCHED_IPI_SUPPORTED)) {
		k_busy_wait(100);
		k_yield();
		continue;
		for (volatile int i = 0; i < 100000; i++)
		;
		z_swap_unlocked();
		}

		/* Note weird API: k_cpu_idle() is called with local

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