Messages in this thread | | | From | Michael Buesch <> | Subject | Threaded interrupt handlers broken? | Date | Sun, 16 Aug 2009 11:53:13 +0200 |
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Hi,
I was trying to use threaded interrupt handlers, but the code always crashes within irq_thread() with a "BUG: spinlock bad magic 00000000". The spinlock that's not properly initialized is from the wait_for_threads waitqueue. It crashes on line 526 (see below). The initialization of the waitqueue struct seems to depend on whether the IRQ is shared or not. I don't know if that's correct, but I patched it to unconditionally initialize the struct. That did not help.
Any ideas?
490 static int irq_thread(void *data) 491 { 492 struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, }; 493 struct irqaction *action = data; 494 struct irq_desc *desc = irq_to_desc(action->irq); 495 int wake; 496 497 sched_setscheduler(current, SCHED_FIFO, ¶m); 498 current->irqaction = action; 499 500 while (!irq_wait_for_interrupt(action)) { 501 502 irq_thread_check_affinity(desc, action); 503 504 atomic_inc(&desc->threads_active); 505 506 spin_lock_irq(&desc->lock); 507 if (unlikely(desc->status & IRQ_DISABLED)) { 508 /* 509 * CHECKME: We might need a dedicated 510 * IRQ_THREAD_PENDING flag here, which 511 * retriggers the thread in check_irq_resend() 512 * but AFAICT IRQ_PENDING should be fine as it 513 * retriggers the interrupt itself --- tglx 514 */ 515 desc->status |= IRQ_PENDING; 516 spin_unlock_irq(&desc->lock); 517 } else { 518 spin_unlock_irq(&desc->lock); 519 520 action->thread_fn(action->irq, action->dev_id); 521 } 522 523 wake = atomic_dec_and_test(&desc->threads_active); 524 525 if (wake && waitqueue_active(&desc->wait_for_threads)) 526 wake_up(&desc->wait_for_threads); <<<<<<<<<<<<<<<<<<<<<<<< 527 } 528 529 /* 530 * Clear irqaction. Otherwise exit_irq_thread() would make 531 * fuzz about an active irq thread going into nirvana. 532 */ 533 current->irqaction = NULL; 534 return 0; 535 }
-- Greetings, Michael.
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