Revert "irq: Always set IRQF_ONESHOT if no primary handler is specified"

This reverts commit f3637a5f2e2eb391ff5757bc83fb5de8f9726464.

It turns out that this breaks several drivers, one example being OMAP
boards which use the on-board OMAP UARTs and the omap-serial driver that
will not boot to userspace after the commit.

Paul Walmsley reports that enabling CONFIG_DEBUG_SHIRQ reveals 'IRQ
handler type mismatch' errors:

  IRQ handler type mismatch for IRQ 74
  current handler: serial idle
  ...

and the reason is that setting IRQF_ONESHOT will now result in those
interrupt handlers having different IRQF flags, and thus being
unsharable.  So the commit log in the reverted commit:

                            "Since it is required for those users and
    there is no difference for others it makes sense to add this flag
    unconditionally."

is simply not true: there may not be any difference from a "actions at
irq time", but there is a *big* difference wrt this flag testing irq
management (see __setup_irq() in kernel/irq/manage.c).

One solution may be to stop verifying IRQF_ONESHOT in __setup_irq(), but
right now the safe course of action is to revert the change.  Let's
revisit this in a later merge window.

Reported-by: Paul Walmsley <paul@pwsan.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Requested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 2e9425889fa8..9b956fa20308 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1331,7 +1331,6 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
                 if (!thread_fn)
                         return -EINVAL;
                 handler = irq_default_primary_handler;
-                irqflags |= IRQF_ONESHOT;
         }
 
         action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);