diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2015-12-13 18:12:30 +0100 |
---|---|---|
committer | Jiri Slaby <jslaby@suse.cz> | 2016-03-03 12:45:54 +0100 |
commit | 5df68eedfb0e3cfa8c23c8b0b28bf032881313e4 (patch) | |
tree | ee48ee8349c94cbedf011d13744ab375d1002814 /kernel | |
parent | 281eea0a8603241edc3fe38c1ab4fa0a92ebec2b (diff) |
genirq: Prevent chip buslock deadlock
commit abc7e40c81d113ef4bacb556f0a77ca63ac81d85 upstream.
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 <fredrik.markstrom@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/irq/manage.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 75a976a8ed58..504bb4b0d226 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1230,6 +1230,7 @@ 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); /* @@ -1243,7 +1244,7 @@ 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; } @@ -1266,6 +1267,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) #endif raw_spin_unlock_irqrestore(&desc->lock, flags); + chip_bus_sync_unlock(desc); unregister_handler_proc(irq, action); @@ -1339,9 +1341,7 @@ void free_irq(unsigned int irq, void *dev_id) desc->affinity_notify = NULL; #endif - chip_bus_lock(desc); kfree(__free_irq(irq, dev_id)); - chip_bus_sync_unlock(desc); } EXPORT_SYMBOL(free_irq); |