diff options
| -rw-r--r-- | include/linux/interrupt.h | 2 | ||||
| -rw-r--r-- | include/linux/irqdesc.h | 2 | ||||
| -rw-r--r-- | kernel/irq/handle.c | 76 | ||||
| -rw-r--r-- | kernel/irq/manage.c | 54 |
4 files changed, 115 insertions, 19 deletions
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 8da6643e39a6..e116fef274cd 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -99,6 +99,7 @@ typedef irqreturn_t (*irq_handler_t)(int, void *); * @thread_fn: interupt handler function for threaded interrupts * @thread: thread pointer for threaded interrupts * @thread_flags: flags related to @thread + * @thread_mask: bitmask for keeping track of @thread activity */ struct irqaction { irq_handler_t handler; @@ -109,6 +110,7 @@ struct irqaction { irq_handler_t thread_fn; struct task_struct *thread; unsigned long thread_flags; + unsigned long thread_mask; const char *name; struct proc_dir_entry *dir; } ____cacheline_internodealigned_in_smp; diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index 2f87d6441302..9eb9cd313052 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -28,6 +28,7 @@ struct timer_rand_state; * @lock: locking for SMP * @affinity_notify: context for notification of affinity changes * @pending_mask: pending rebalanced interrupts + * @threads_oneshot: bitfield to handle shared oneshot threads * @threads_active: number of irqaction threads currently running * @wait_for_threads: wait queue for sync_irq to wait for threaded handlers * @dir: /proc/irq/ procfs entry @@ -86,6 +87,7 @@ struct irq_desc { cpumask_var_t pending_mask; #endif #endif + unsigned long threads_oneshot; atomic_t threads_active; wait_queue_head_t wait_for_threads; #ifdef CONFIG_PROC_FS diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c index b110c835e070..517561fc7317 100644 --- a/kernel/irq/handle.c +++ b/kernel/irq/handle.c @@ -51,6 +51,68 @@ static void warn_no_thread(unsigned int irq, struct irqaction *action) "but no thread function available.", irq, action->name); } +static void irq_wake_thread(struct irq_desc *desc, struct irqaction *action) +{ + /* + * Wake up the handler thread for this action. In case the + * thread crashed and was killed we just pretend that we + * handled the interrupt. The hardirq handler has disabled the + * device interrupt, so no irq storm is lurking. If the + * RUNTHREAD bit is already set, nothing to do. + */ + if (test_bit(IRQTF_DIED, &action->thread_flags) || + test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags)) + return; + + /* + * It's safe to OR the mask lockless here. We have only two + * places which write to threads_oneshot: This code and the + * irq thread. + * + * This code is the hard irq context and can never run on two + * cpus in parallel. If it ever does we have more serious + * problems than this bitmask. + * + * The irq threads of this irq which clear their "running" bit + * in threads_oneshot are serialized via desc->lock against + * each other and they are serialized against this code by + * IRQS_INPROGRESS. + * + * Hard irq handler: + * + * spin_lock(desc->lock); + * desc->state |= IRQS_INPROGRESS; + * spin_unlock(desc->lock); + * set_bit(IRQTF_RUNTHREAD, &action->thread_flags); + * desc->threads_oneshot |= mask; + * spin_lock(desc->lock); + * desc->state &= ~IRQS_INPROGRESS; + * spin_unlock(desc->lock); + * + * irq thread: + * + * again: + * spin_lock(desc->lock); + * if (desc->state & IRQS_INPROGRESS) { + * spin_unlock(desc->lock); + * while(desc->state & IRQS_INPROGRESS) + * cpu_relax(); + * goto again; + * } + * if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags)) + * desc->threads_oneshot &= ~mask; + * spin_unlock(desc->lock); + * + * So either the thread waits for us to clear IRQS_INPROGRESS + * or we are waiting in the flow handler for desc->lock to be + * released before we reach this point. The thread also checks + * IRQTF_RUNTHREAD under desc->lock. If set it leaves + * threads_oneshot untouched and runs the thread another time. + */ + desc->threads_oneshot |= action->thread_mask; + wake_up_process(action->thread); +} + irqreturn_t handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action) { @@ -85,19 +147,7 @@ handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action) break; } - /* - * Wake up the handler thread for this - * action. In case the thread crashed and was - * killed we just pretend that we handled the - * interrupt. The hardirq handler above has - * disabled the device interrupt, so no irq - * storm is lurking. - */ - if (likely(!test_bit(IRQTF_DIED, - &action->thread_flags))) { - set_bit(IRQTF_RUNTHREAD, &action->thread_flags); - wake_up_process(action->thread); - } + irq_wake_thread(desc, action); /* Fall through to add to randomness */ case IRQ_HANDLED: diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 01f8a9519e63..2301de19ac7d 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -617,8 +617,11 @@ static int irq_wait_for_interrupt(struct irqaction *action) * handler finished. unmask if the interrupt has not been disabled and * is marked MASKED. */ -static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc) +static void irq_finalize_oneshot(struct irq_desc *desc, + struct irqaction *action, bool force) { + if (!(desc->istate & IRQS_ONESHOT)) + return; again: chip_bus_lock(desc); raw_spin_lock_irq(&desc->lock); @@ -631,6 +634,11 @@ again: * on the other CPU. If we unmask the irq line then the * interrupt can come in again and masks the line, leaves due * to IRQS_INPROGRESS and the irq line is masked forever. + * + * This also serializes the state of shared oneshot handlers + * versus "desc->threads_onehsot |= action->thread_mask;" in + * irq_wake_thread(). See the comment there which explains the + * serialization. */ if (unlikely(desc->istate & IRQS_INPROGRESS)) { raw_spin_unlock_irq(&desc->lock); @@ -639,11 +647,23 @@ again: goto again; } - if (!(desc->istate & IRQS_DISABLED) && (desc->istate & IRQS_MASKED)) { + /* + * Now check again, whether the thread should run. Otherwise + * we would clear the threads_oneshot bit of this thread which + * was just set. + */ + if (!force && test_bit(IRQTF_RUNTHREAD, &action->thread_flags)) + goto out_unlock; + + desc->threads_oneshot &= ~action->thread_mask; + + if (!desc->threads_oneshot && !(desc->istate & IRQS_DISABLED) && + (desc->istate & IRQS_MASKED)) { irq_compat_clr_masked(desc); desc->istate &= ~IRQS_MASKED; desc->irq_data.chip->irq_unmask(&desc->irq_data); } +out_unlock: raw_spin_unlock_irq(&desc->lock); chip_bus_sync_unlock(desc); } @@ -691,7 +711,7 @@ static int irq_thread(void *data) }; struct irqaction *action = data; struct irq_desc *desc = irq_to_desc(action->irq); - int wake, oneshot = desc->istate & IRQS_ONESHOT; + int wake; sched_setscheduler(current, SCHED_FIFO, ¶m); current->irqaction = action; @@ -719,8 +739,7 @@ static int irq_thread(void *data) action->thread_fn(action->irq, action->dev_id); - if (oneshot) - irq_finalize_oneshot(action->irq, desc); + irq_finalize_oneshot(desc, action, false); } wake = atomic_dec_and_test(&desc->threads_active); @@ -729,6 +748,9 @@ static int irq_thread(void *data) wake_up(&desc->wait_for_threads); } + /* Prevent a stale desc->threads_oneshot */ + irq_finalize_oneshot(desc, action, true); + /* * Clear irqaction. Otherwise exit_irq_thread() would make * fuzz about an active irq thread going into nirvana. @@ -743,6 +765,7 @@ static int irq_thread(void *data) void exit_irq_thread(void) { struct task_struct *tsk = current; + struct irq_desc *desc; if (!tsk->irqaction) return; @@ -751,6 +774,14 @@ void exit_irq_thread(void) "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n", tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq); + desc = irq_to_desc(tsk->irqaction->irq); + + /* + * Prevent a stale desc->threads_oneshot. Must be called + * before setting the IRQTF_DIED flag. + */ + irq_finalize_oneshot(desc, tsk->irqaction, true); + /* * Set the THREAD DIED flag to prevent further wakeups of the * soon to be gone threaded handler. @@ -767,7 +798,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) { struct irqaction *old, **old_ptr; const char *old_name = NULL; - unsigned long flags; + unsigned long flags, thread_mask = 0; int ret, nested, shared = 0; cpumask_var_t mask; @@ -865,12 +896,23 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) /* add new interrupt at end of irq queue */ do { + thread_mask |= old->thread_mask; old_ptr = &old->next; old = *old_ptr; } while (old); shared = 1; } + /* + * Setup the thread mask for this irqaction. Unlikely to have + * 32 resp 64 irqs sharing one line, but who knows. + */ + if (new->flags & IRQF_ONESHOT && thread_mask == ~0UL) { + ret = -EBUSY; + goto out_mask; + } + new->thread_mask = 1 << ffz(thread_mask); + if (!shared) { irq_chip_set_defaults(desc->irq_data.chip); |