path: root/kernel/irq
diff options
authorThomas Gleixner <>2015-12-13 18:12:30 +0100
committerThomas Gleixner <>2015-12-14 09:45:06 +0100
commitabc7e40c81d113ef4bacb556f0a77ca63ac81d85 (patch)
tree06c8130b3f1f442a195135e7a032d28b1fa6bbdf /kernel/irq
parent9f9499ae8e6415cefc4fe0a96ad0e27864353c89 (diff)
genirq: Prevent chip buslock deadlock
If a interrupt chip utilizes chip->buslock then free_irq() can deadlock in the following way: CPU0 CPU1 interrupt(X) (Shared or spurious) free_irq(X) interrupt_thread(X) chip_bus_lock(X) irq_finalize_oneshot(X) chip_bus_lock(X) synchronize_irq(X) synchronize_irq() waits for the interrupt thread to complete, i.e. forever. Solution is simple: Drop chip_bus_lock() before calling synchronize_irq() as we do with the irq_desc lock. There is nothing to be protected after the point where irq_desc lock has been released. This adds chip_bus_lock/unlock() to the remove_irq() code path, but that's actually correct in the case where remove_irq() is called on such an interrupt. The current users of remove_irq() are not affected as none of those interrupts is on a chip which requires buslock. Reported-by: Fredrik Markström <> Signed-off-by: Thomas Gleixner <> Cc:
Diffstat (limited to 'kernel/irq')
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0eebaeef317b..6ead200370da 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1434,6 +1434,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
if (!desc)
return NULL;
+ chip_bus_lock(desc);
raw_spin_lock_irqsave(&desc->lock, flags);
@@ -1447,7 +1448,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
if (!action) {
WARN(1, "Trying to free already-free IRQ %d\n", irq);
raw_spin_unlock_irqrestore(&desc->lock, flags);
+ chip_bus_sync_unlock(desc);
return NULL;
@@ -1475,6 +1476,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
raw_spin_unlock_irqrestore(&desc->lock, flags);
+ chip_bus_sync_unlock(desc);
unregister_handler_proc(irq, action);
@@ -1553,9 +1555,7 @@ void free_irq(unsigned int irq, void *dev_id)
desc->affinity_notify = NULL;
- chip_bus_lock(desc);
kfree(__free_irq(irq, dev_id));
- chip_bus_sync_unlock(desc);