[tip:x86/apic] x86, ioapic: Add proper legacy interrupt check to mp_map_pin_to_irq()

[tip-bot for Andy Shevchenko <tipbot@zytor.com>]

Commit-ID:  c528d8b32d130956b3c158394d854e948cfc3411
Gitweb:     http://git.kernel.org/tip/c528d8b32d130956b3c158394d854e948cfc3411
Author:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
AuthorDate: Wed, 10 Dec 2014 20:29:25 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 10 Dec 2014 23:43:56 +0100

x86, ioapic: Add proper legacy interrupt check to mp_map_pin_to_irq()

Since commit bfa644bfa9e3 (x86, irq: Convert IOAPIC to use hierarchy
irqdomain interfaces) Intel MID platforms crashes on boot:

 Enabling APIC mode:  Flat.  Using 1 I/O APICs
 BUG: unable to handle kernel NULL pointer dereference at 00000018
 IP: [<c107bdc6>] __irq_domain_alloc_irqs+0xff/0x250

The reason is that mp_map_pin_to_irq() assumes blindly that any non
PCI interrupt is legacy, but thats wrong for MID platforms as they
have no legacy interrupt support.

alloc_irq_from_domain() and mp_init_irq_at_boot() have checks for
this, but mp_map_pin_to_irq() is lacking one.

Instead of copying the same code another time, move the check to an
inline function and use it everywhere.

[ tglx: Massaged changelog ]

Fixes: bfa644bfa9e3 'x86, irq: Convert IOAPIC to use hierarchy irqdomain interfaces'
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: David Cohen <david.a.cohen@linux.intel.com>
Link: http://lkml.kernel.org/r/1418236165-13961-1-git-send-email-andriy.shevchenko@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/apic/io_apic.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index ed22b4c..f60e06e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -149,6 +149,11 @@ static inline u32 mp_pin_to_gsi(int ioapic, int pin)
 	return mp_ioapic_gsi_routing(ioapic)->gsi_base + pin;
 }
 
+static inline bool mp_is_legacy_irq(int irq)
+{
+	return irq >= 0 && irq < nr_legacy_irqs();
+}
+
 /*
  * Initialize all legacy IRQs and all pins on the first IOAPIC
  * if we have legacy interrupt controller. Kernel boot option "pirq="
@@ -159,7 +164,7 @@ static inline int mp_init_irq_at_boot(int ioapic, int irq)
 	if (!nr_legacy_irqs())
 		return 0;
 
-	return ioapic == 0 || (irq >= 0 && irq < nr_legacy_irqs());
+	return ioapic == 0 || mp_is_legacy_irq(irq);
 }
 
 static inline struct irq_domain *mp_ioapic_irqdomain(int ioapic)
@@ -960,7 +965,7 @@ static int alloc_irq_from_domain(struct irq_domain *domain, int ioapic, u32 gsi,
 		 */
 		if (!ioapic_initialized || gsi >= nr_legacy_irqs())
 			irq = gsi;
-		legacy = irq >= 0 && irq < nr_legacy_irqs();
+		legacy = mp_is_legacy_irq(irq);
 		break;
 	case IOAPIC_DOMAIN_STRICT:
 		irq = gsi;
@@ -1031,8 +1036,8 @@ static int mp_map_pin_to_irq(u32 gsi, int idx, int ioapic, int pin,
 		return -ENOSYS;
 
 	if (idx >= 0 && test_bit(mp_irqs[idx].srcbus, mp_bus_not_pci)) {
-		legacy = true;
 		irq = mp_irqs[idx].srcbusirq;
+		legacy = mp_is_legacy_irq(irq);
 	}
 
 	mutex_lock(&ioapic_mutex);