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Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull irq fix from Thomas Gleixner:
 "Fix the fallout from reworking the locking and resource management in
  request/free_irq()"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Keep chip buslock across irq_request/release_resources()
This commit is contained in:
Linus Torvalds 2017-07-17 13:00:36 -07:00
commit 935acd3f5e
1 changed files with 53 additions and 10 deletions
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63
kernel/irq/manage.c
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@ -1090,6 +1090,16 @@ setup_irq_thread(struct irqaction *new, unsigned int irq, bool secondary)
/*
* Internal function to register an irqaction - typically used to
* allocate special interrupts that are part of the architecture.
*
* Locking rules:
*
* desc->request_mutex Provides serialization against a concurrent free_irq()
* chip_bus_lock Provides serialization for slow bus operations
* desc->lock Provides serialization against hard interrupts
*
* chip_bus_lock and desc->lock are sufficient for all other management and
* interrupt related functions. desc->request_mutex solely serializes
* request/free_irq().
*/
static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
@ -1167,20 +1177,35 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
new->flags &= ~IRQF_ONESHOT;
/*
* Protects against a concurrent __free_irq() call which might wait
* for synchronize_irq() to complete without holding the optional
* chip bus lock and desc->lock.
*/
mutex_lock(&desc->request_mutex);
/*
* Acquire bus lock as the irq_request_resources() callback below
* might rely on the serialization or the magic power management
* functions which are abusing the irq_bus_lock() callback,
*/
chip_bus_lock(desc);
/* First installed action requests resources. */
if (!desc->action) {
ret = irq_request_resources(desc);
if (ret) {
pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
new->name, irq, desc->irq_data.chip->name);
goto out_mutex;
goto out_bus_unlock;
}
}
chip_bus_lock(desc);
/*
* The following block of code has to be executed atomically
* protected against a concurrent interrupt and any of the other
* management calls which are not serialized via
* desc->request_mutex or the optional bus lock.
*/
raw_spin_lock_irqsave(&desc->lock, flags);
old_ptr = &desc->action;
@ -1286,10 +1311,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
ret = __irq_set_trigger(desc,
new->flags & IRQF_TRIGGER_MASK);
if (ret) {
irq_release_resources(desc);
if (ret)
goto out_unlock;
}
}
desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
@ -1385,12 +1408,10 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
out_unlock:
raw_spin_unlock_irqrestore(&desc->lock, flags);
chip_bus_sync_unlock(desc);
if (!desc->action)
irq_release_resources(desc);
out_mutex:
out_bus_unlock:
chip_bus_sync_unlock(desc);
mutex_unlock(&desc->request_mutex);
out_thread:
@ -1472,6 +1493,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
WARN(1, "Trying to free already-free IRQ %d\n", irq);
raw_spin_unlock_irqrestore(&desc->lock, flags);
chip_bus_sync_unlock(desc);
mutex_unlock(&desc->request_mutex);
return NULL;
}
@ -1498,6 +1520,20 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
#endif
raw_spin_unlock_irqrestore(&desc->lock, flags);
/*
* Drop bus_lock here so the changes which were done in the chip
* callbacks above are synced out to the irq chips which hang
* behind a slow bus (I2C, SPI) before calling synchronize_irq().
*
* Aside of that the bus_lock can also be taken from the threaded
* handler in irq_finalize_oneshot() which results in a deadlock
* because synchronize_irq() would wait forever for the thread to
* complete, which is blocked on the bus lock.
*
* The still held desc->request_mutex() protects against a
* concurrent request_irq() of this irq so the release of resources
* and timing data is properly serialized.
*/
chip_bus_sync_unlock(desc);
unregister_handler_proc(irq, action);
@ -1530,8 +1566,15 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
}
}
/* Last action releases resources */
if (!desc->action) {
/*
* Reaquire bus lock as irq_release_resources() might
* require it to deallocate resources over the slow bus.
*/
chip_bus_lock(desc);
irq_release_resources(desc);
chip_bus_sync_unlock(desc);
irq_remove_timings(desc);
}