From ccf0faa7d26d56deca7928b521d07be40504466a Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Thu, 25 Oct 2012 13:40:54 -0700 Subject: [PATCH] altos: Leave interrupts disabled while checking for task to run Otherwise, we run the risk of an interrupt waking a task after we've decided to idle the CPU. Signed-off-by: Keith Packard --- src/avr/ao_arch.h | 19 +++++++++++++++---- src/cc1111/ao_arch.h | 11 +++++++---- src/core/ao_task.c | 28 +++++++++++++--------------- src/stm/ao_arch_funcs.h | 4 +++- 4 files changed, 38 insertions(+), 24 deletions(-) diff --git a/src/avr/ao_arch.h b/src/avr/ao_arch.h index c82612a8..d626e830 100644 --- a/src/avr/ao_arch.h +++ b/src/avr/ao_arch.h @@ -112,7 +112,6 @@ extern uint8_t ao_cpu_sleep_disable; asm("push r9" "\n\t" "push r8" "\n\t" "push r7" "\n\t" "push r6" "\n\t" "push r5"); \ asm("push r4" "\n\t" "push r3" "\n\t" "push r2" "\n\t" "push r1" "\n\t" "push r0"); \ asm("in r0, __SREG__" "\n\t" "push r0"); \ - sei(); \ } while (0) #define ao_arch_save_stack() do { \ @@ -124,16 +123,28 @@ extern uint8_t ao_cpu_sleep_disable; #define ao_arch_isr_stack() /* nothing */ -#define ao_arch_cpu_idle() do { \ - if (!ao_cpu_sleep_disable) \ +/* Idle the CPU (if possible) waiting for an interrupt. Enabling + * interrupts and sleeping the CPU must be adjacent to eliminate race + * conditions. In all cases, we execute a single nop with interrupts + * enabled + */ +#define ao_arch_wait_interrupt() do { \ + if (!ao_cpu_sleep_disable) { \ + sleep_enable(); \ + sei(); \ sleep_cpu(); \ + sleep_disable(); \ + } else { \ + sei(); \ + } \ + ao_arch_nop(); \ + cli(); \ } while (0) #define ao_arch_restore_stack() do { \ uint8_t sp_l, sp_h; \ sp_l = (uint16_t) ao_cur_task->sp; \ sp_h = ((uint16_t) ao_cur_task->sp) >> 8; \ - cli(); \ asm("out __SP_H__,%0" : : "r" (sp_h) ); \ asm("out __SP_L__,%0" : : "r" (sp_l) ); \ asm("pop r0" "\n\t" \ diff --git a/src/cc1111/ao_arch.h b/src/cc1111/ao_arch.h index 39468e06..9097557f 100644 --- a/src/cc1111/ao_arch.h +++ b/src/cc1111/ao_arch.h @@ -112,9 +112,7 @@ extern AO_ROMCONFIG_SYMBOL(0x00a6) uint32_t ao_radio_cal; /* Push ACC first, as when restoring the context it must be restored \ * last (it is used to set the IE register). */ \ push ACC \ - /* Store the IE register then enable interrupts. */ \ push _IEN0 \ - setb _EA \ push DPL \ push DPH \ push b \ @@ -150,11 +148,16 @@ extern AO_ROMCONFIG_SYMBOL(0x00a6) uint32_t ao_radio_cal; /* Empty the stack; might as well let interrupts have the whole thing */ #define ao_arch_isr_stack() (SP = AO_STACK_START - 1) -/* Idle the CPU, waking when an interrupt occurs */ -#define ao_arch_cpu_idle() (PCON = PCON_IDLE) #define ao_arch_block_interrupts() __asm clr _EA __endasm #define ao_arch_release_interrupts() __asm setb _EA __endasm +/* Idle the CPU, waking when an interrupt occurs */ +#define ao_arch_wait_interrupt() do { \ + ao_arch_release_interrupts(); \ + (PCON = PCON_IDLE); \ + ao_arch_block_interrupts(); \ + } while (0) + #define ao_arch_restore_stack() { \ uint8_t stack_len; \ __data uint8_t *stack_ptr; \ diff --git a/src/core/ao_task.c b/src/core/ao_task.c index a11979f0..985c37fa 100644 --- a/src/core/ao_task.c +++ b/src/core/ao_task.c @@ -331,6 +331,7 @@ ao_yield(void) ao_arch_naked_define } ao_arch_isr_stack(); + ao_arch_block_interrupts(); #if AO_CHECK_STACK in_yield = 1; @@ -339,21 +340,19 @@ ao_yield(void) ao_arch_naked_define * this loop will run forever, which is just fine */ #if HAS_TASK_QUEUE - if (ao_cur_task->wchan == NULL) { - uint32_t flags; - flags = ao_arch_irqsave(); + /* If the current task is running, move it to the + * end of the queue to allow other tasks a chance + */ + if (ao_cur_task->wchan == NULL) ao_task_to_run_queue(ao_cur_task); - ao_arch_irqrestore(flags); - } ao_cur_task = NULL; - for (;;) { ao_arch_memory_barrier(); if (!ao_list_is_empty(&run_queue)) break; - ao_arch_cpu_idle(); + /* Wait for interrupts when there's nothing ready */ + ao_arch_wait_interrupt(); } - ao_cur_task = ao_list_first_entry(&run_queue, struct ao_task, queue); #else { @@ -374,20 +373,19 @@ ao_yield(void) ao_arch_naked_define (int16_t) (ao_time() - ao_cur_task->alarm) >= 0) break; - /* Enter lower power mode when there isn't anything to do */ + /* Wait for interrupts when there's nothing ready */ if (ao_cur_task_index == ao_last_task_index) - ao_arch_cpu_idle(); + ao_arch_wait_interrupt(); } -#if HAS_SAMPLE_PROFILE - ao_cur_task->start = ao_sample_profile_timer_value(); -#endif } #endif +#if HAS_SAMPLE_PROFILE + ao_cur_task->start = ao_sample_profile_timer_value(); +#endif #if HAS_STACK_GUARD ao_mpu_stack_guard(ao_cur_task->stack); #endif #if AO_CHECK_STACK - ao_arch_block_interrupts(); in_yield = 0; #endif ao_arch_restore_stack(); @@ -519,7 +517,7 @@ ao_task_info(void) task->name, (int) task->wchan); } -#if HAS_TASK_QUEUE +#if HAS_TASK_QUEUE && DEBUG ao_task_validate(); #endif } diff --git a/src/stm/ao_arch_funcs.h b/src/stm/ao_arch_funcs.h index ca451a53..d6ab1465 100644 --- a/src/stm/ao_arch_funcs.h +++ b/src/stm/ao_arch_funcs.h @@ -299,8 +299,10 @@ static inline void ao_arch_restore_stack(void) { #define ao_arch_isr_stack() -#define ao_arch_cpu_idle() do { \ +#define ao_arch_wait_interrupt() do { \ asm(".global ao_idle_loc\n\twfi\nao_idle_loc:"); \ + ao_arch_release_interrupts(); \ + ao_arch_block_interrupts(); \ } while (0) #define ao_arch_critical(b) do { \ -- 2.30.2