genirq: Remove IRQF_DISABLED from core code

Remove all code which is related to IRQF_DISABLED from the core kernel
code. IRQF_DISABLED still exists as a flag, but becomes a NOOP and
will be removed after a grace period. That way we can easily revert to
the previous behaviour by just restoring the core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Miller <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Linus Torvalds <torvalds@osdl.org>
LKML-Reference: <20100326000405.991244690@linutronix.de>

3 files changed, 9 insertions, 31 deletions

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index ed511af0f79a..9c31c2e63684 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -589,3 +589,10 @@ Why:	Useful in 2003, implementation is a hack.
         Generally invoked by accident today.
         Seen as doing more harm than good.
 Who:    Len Brown <len.brown@intel.com>
+
+----------------------------
+
+What:   IRQF_DISABLED
+When:   2.6.36
+Why:    The flag is a NOOP as we run interrupt handlers with interrupts disabled
+Who:    Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index d7e7a7660c6c..e6d2f4441fda 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -39,7 +39,8 @@
  * These flags used only by the kernel as part of the
  * irq handling routines.
  *
- * IRQF_DISABLED - keep irqs disabled when calling the action handler
+ * IRQF_DISABLED - keep irqs disabled when calling the action handler.
+ *                 DEPRECATED. This flag is a NOOP and scheduled to be removed
  * IRQF_SAMPLE_RANDOM - irq is used to feed the random generator
  * IRQF_SHARED - allow sharing the irq among several devices
  * IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 84f32278ff1f..444d5a81a209 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -757,16 +757,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                 if (new->flags & IRQF_ONESHOT)
                         desc->status |= IRQ_ONESHOT;
 
-                /*
-                 * Force MSI interrupts to run with interrupts
-                 * disabled. The multi vector cards can cause stack
-                 * overflows due to nested interrupts when enough of
-                 * them are directed to a core and fire at the same
-                 * time.
-                 */
-                if (desc->msi_desc)
-                        new->flags |= IRQF_DISABLED;
-
                 if (!(desc->status & IRQ_NOAUTOEN)) {
                         desc->depth = 0;
                         desc->status &= ~IRQ_DISABLED;
@@ -1027,7 +1017,6 @@ EXPORT_SYMBOL(free_irq);
  *      Flags:
  *
  *      IRQF_SHARED             Interrupt is shared
- *      IRQF_DISABLED   Disable local interrupts while processing
  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
  *      IRQF_TRIGGER_*          Specify active edge(s) or level
  *
@@ -1041,25 +1030,6 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
         int retval;
 
         /*
-         * handle_IRQ_event() always ignores IRQF_DISABLED except for
-         * the _first_ irqaction (sigh).  That can cause oopsing, but
-         * the behavior is classified as "will not fix" so we need to
-         * start nudging drivers away from using that idiom.
-         */
-        if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
-                                        (IRQF_SHARED|IRQF_DISABLED)) {
-                pr_warning(
-                  "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
-                        irq, devname);
-        }
-
-#ifdef CONFIG_LOCKDEP
-        /*
-         * Lockdep wants atomic interrupt handlers:
-         */
-        irqflags |= IRQF_DISABLED;
-#endif
-        /*
          * Sanity-check: shared interrupts must pass in a real dev-ID,
          * otherwise we'll have trouble later trying to figure out
          * which interrupt is which (messes up the interrupt freeing