riscv: Don't reschedule on back-to-back interrupts (535fc38f) · Commits · Wenxi XU / zephyr

In some cases the 'reschedule' code path is executed when the current thread is the same as the next thread in the ready Q. If this happens, the swap_return_value of the thread is ifalsely being reset to -EAGAIN. This commit prevents the rescheduling code to run if the current thread is the same as the thread in the ready Q. Signed-off-by:

Wolfgang Reißnegger <gnagflow@fb.com>

arch/riscv/core/isr.S

+12 −0

Original line number	Diff line number	Diff line
		@@ -811,6 +811,18 @@ skip_fp_move_irq:
		#endif /* CONFIG_USERSPACE */

		reschedule:
		/*
		* Check if the current thread is the same as the thread on the ready Q. If
		* so, do not reschedule.
		* Note:
		* Sometimes this code is execute back-to-back before the target thread
		* has a chance to run. If this happens, the current thread and the
		* target thread will be the same.
		*/
		la t0, _kernel
		RV_OP_LOADREG t2, _kernel_offset_to_current(t0)
		RV_OP_LOADREG t3, _kernel_offset_to_ready_q_cache(t0)
		beq t2, t3, no_reschedule

		#if CONFIG_INSTRUMENT_THREAD_SWITCHING
		call z_thread_mark_switched_out

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