[GIT pull] irq fixes for 4.18

[Thomas Gleixner]

Linus,

please pull the latest irq-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 
irq-urgent-for-linus

A single bugfix for the irq core to prevent silent data corruption and
malfunction of threaded interrupts under certain conditions.

Thanks,

        tglx

------------------>
Thomas Gleixner (1):
      genirq: Make force irq threading setup more robust


 kernel/irq/manage.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index daeabd791d58..9a8b7ba9aa88 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1068,6 +1068,13 @@ static int irq_setup_forced_threading(struct irqaction 
*new)
        if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
                return 0;
 
+       /*
+        * No further action required for interrupts which are requested as
+        * threaded interrupts already
+        */
+       if (new->handler == irq_default_primary_handler)
+               return 0;
+
        new->flags |= IRQF_ONESHOT;
 
        /*
@@ -1075,7 +1082,7 @@ static int irq_setup_forced_threading(struct irqaction 
*new)
         * thread handler. We force thread them as well by creating a
         * secondary action.
         */
-       if (new->handler != irq_default_primary_handler && new->thread_fn) {
+       if (new->handler && new->thread_fn) {
                /* Allocate the secondary action */
                new->secondary = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
                if (!new->secondary)