genirq: Delegate irq affinity setting to the irq thread

irq_set_thread_affinity() calls set_cpus_allowed_ptr() which might
sleep, but irq_set_thread_affinity() is called with desc->lock held
and can be called from hard interrupt context as well. The code has
another bug as it does not hold a ref on the task struct as required
by set_cpus_allowed_ptr().

Just set the IRQTF_AFFINITY bit in action->thread_flags. The next time
the thread runs it migrates itself. Solves all of the above problems
nicely.

Add kerneldoc to irq_set_thread_affinity() while at it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c
index cfe767ca1545..fcb6c96f2627 100644
--- a/kernel/irq/migration.c
+++ b/kernel/irq/migration.c
@@ -45,7 +45,7 @@ void move_masked_irq(int irq)
                    < nr_cpu_ids))
                 if (!desc->chip->set_affinity(irq, desc->pending_mask)) {
                         cpumask_copy(desc->affinity, desc->pending_mask);
-                        irq_set_thread_affinity(desc, desc->pending_mask);
+                        irq_set_thread_affinity(desc);
                 }
 
         cpumask_clear(desc->pending_mask);