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fix race condition of handle_intr.

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This commit is contained in:
NIIBE Yutaka
2013-05-29 12:08:21 +09:00
parent b5cdd769ee
commit 1d535e3be8
4 changed files with 56 additions and 18 deletions
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55
chopstx.c
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@@ -402,6 +402,7 @@ svc (void)
{
register uint32_t r0 asm ("r0");
register uint32_t orig_r0 asm ("r2");
register uint32_t *orig_r1 asm ("r3");
asm volatile ("ldr r1, =running\n\t"
"ldr r0, [r1]\n\t"
@@ -414,8 +415,10 @@ svc (void)
"mov r6, r11\n\t"
"mrs r7, PSP\n\t" /* r13(=SP) in user space. */
"stm r2, {r3, r4, r5, r6, r7}\n\t"
"ldr r2, [r7]"
: "=r" (r0), "=r" (orig_r0) : /* no input */ : "memory");
"ldr r2, [r7]\n\t"
"ldr r3, [r7, #4]\n\t"
: "=r" (r0), "=r" (orig_r0), "=r" (orig_r1)
: /* no input */ : "memory");
if (orig_r0)
{
@@ -427,6 +430,17 @@ svc (void)
"cpsie i" /* Unmask interrupts. */
: /* no output */ : /* no input */ : "memory");
}
else if (orig_r1)
{
asm volatile ("cpsid i" : : : "memory");
if (*orig_r1)
{
running->state = THREAD_RUNNING;
asm volatile ("cpsie i" : : : "memory");
return;
}
/* call sched with keeping interrupt disabled. */
}
asm volatile ("b sched"
: /* no output */: /* no input */ : "memory");
@@ -581,6 +595,7 @@ chx_set_intr_prio (uint8_t n)
}
static chopstx_intr_t *intr_top;
static volatile uint32_t *const ICSR = (uint32_t *const)0xE000ED04;
void
chx_handle_intr (void)
@@ -597,12 +612,15 @@ chx_handle_intr (void)
if (intr->irq_num == irq_num)
break;
if (intr && intr->tp && intr->tp->state == THREAD_WAIT_INT)
if (intr)
{
intr->ready++;
chx_ready_enqueue (intr->tp);
if (running == NULL || running->prio < intr->tp->prio)
chx_request_preemption ();
if (intr->tp != running && intr->tp->state == THREAD_WAIT_INT)
{
chx_ready_enqueue (intr->tp);
if (running == NULL || running->prio < intr->tp->prio)
chx_request_preemption ();
}
}
asm volatile ("cpsie i" : : : "memory");
}
@@ -643,18 +661,17 @@ chx_init (struct chx_thread *tp)
static void
chx_request_preemption (void)
{
static volatile uint32_t *const ICSR = (uint32_t *const)0xE000ED04;
*ICSR = (1 << 28);
asm volatile ("" : : : "memory");
}
static void
chx_sched (void)
chx_sched (uint32_t *ptr)
{
register uint32_t r0 asm ("r0") = 0;
register uint32_t r1 asm ("r1") = (uint32_t)ptr;
asm volatile ("svc #0" : : "r" (r0) : "memory");
asm volatile ("svc #0" : : "r" (r0), "r" (r1) : "memory");
}
static void
@@ -696,7 +713,7 @@ chx_exit (void *retval)
running->state = THREAD_FINISHED;
chx_UNLOCK (&q_exit.lock);
asm volatile ("cpsie i" : : "r" (r4) : "memory");
chx_sched ();
chx_sched (NULL);
/* never comes here. */
for (;;);
}
@@ -804,7 +821,7 @@ chopstx_usec_wait (uint32_t usec)
uint32_t usec0 = (usec > 200*1000) ? 200*1000: usec;
chx_timer_insert (running, usec0);
chx_sched ();
chx_sched (NULL);
usec -= usec0;
}
@@ -876,7 +893,7 @@ chopstx_mutex_lock (chopstx_mutex_t *mutex)
tp->v = (uint32_t)mutex;
chx_UNLOCK (&mutex->lock);
asm volatile ("cpsie i" : : : "memory");
chx_sched ();
chx_sched (NULL);
}
}
@@ -925,7 +942,7 @@ chopstx_cond_wait (chopstx_cond_t *cond, chopstx_mutex_t *mutex)
chx_UNLOCK (&cond->lock);
asm volatile ("cpsie i" : : : "memory");
chx_sched ();
chx_sched (NULL);
if (mutex)
chopstx_mutex_lock (mutex);
@@ -1039,12 +1056,16 @@ chopstx_intr_wait (chopstx_intr_t *intr)
{
asm volatile ("cpsid i" : : : "memory");
chx_enable_intr (intr->irq_num);
while (intr->ready == 0)
if (intr->ready == 0)
{
running->state = THREAD_WAIT_INT;
running->v = 0;
asm volatile ("cpsie i" : : : "memory");
chx_sched ();
/*
* Here is the race with chx_handle_intr.
* Bring a pointer to intr->ready, so that it won't sleep when ready.
*/
chx_sched (&intr->ready);
asm volatile ("cpsid i" : : : "memory");
}
intr->ready--;
@@ -1103,7 +1124,7 @@ chopstx_join (chopstx_t thd, void **ret)
if (tp->prio < running->prio)
tp->prio = running->prio;
asm volatile ("cpsie i" : : : "memory");
chx_sched ();
chx_sched (NULL);
asm volatile ("cpsid i" : : : "memory");
}