[PATCH v2 22/26] x86, irq: Make ioapics loop skip blank slots

[Yinghai Lu <yinghai@kernel.org>]

When multiple ioapics get added and removed, we could have blank slots
in middle of ioapics array.

Add skip code for this case by checking nr_registers.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
---
 arch/x86/kernel/apic/io_apic.c |   29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 4a9ccf6..d4c68d9 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -793,7 +793,8 @@ int save_ioapic_entries(void)
 	int err = 0;
 
 	for (apic = 0; apic < nr_ioapics; apic++) {
-		if (!ioapics[apic].saved_registers) {
+		if (!ioapics[apic].saved_registers &&
+		    ioapics[apic].nr_registers) {
 			err = -ENOMEM;
 			continue;
 		}
@@ -899,9 +900,12 @@ static int __init find_isa_irq_apic(int irq, int type)
 	if (i < mp_irq_entries) {
 		int ioapic_idx;
 
-		for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++)
+		for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++) {
+			if (!ioapics[ioapic_idx].nr_registers)
+				continue;
 			if (mpc_ioapic_id(ioapic_idx) == mp_irqs[i].dstapic)
 				return ioapic_idx;
+		}
 	}
 
 	return -1;
@@ -1121,10 +1125,13 @@ int IO_APIC_get_PCI_irq_vector(int bus, int slot, int pin,
 	for (i = 0; i < mp_irq_entries; i++) {
 		int lbus = mp_irqs[i].srcbus;
 
-		for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++)
+		for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++) {
+			if (!ioapics[ioapic_idx].nr_registers)
+				continue;
 			if (mpc_ioapic_id(ioapic_idx) == mp_irqs[i].dstapic ||
 			    mp_irqs[i].dstapic == MP_APIC_ALL)
 				break;
+		}
 
 		if (!test_bit(lbus, mp_bus_not_pci) &&
 		    !mp_irqs[i].irqtype &&
@@ -2084,6 +2091,9 @@ void __init setup_ioapic_ids_from_mpc_nocheck(void)
 	 * Set the IOAPIC ID to the value stored in the MPC table.
 	 */
 	for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++) {
+		if (!ioapics[ioapic_idx].nr_registers)
+			continue;
+
 		/* Read the register 0 value */
 		raw_spin_lock_irqsave(&ioapic_lock, flags);
 		reg_00.raw = io_apic_read(ioapic_idx, 0);
@@ -3013,8 +3023,12 @@ static void ioapic_resume(void)
 {
 	int ioapic_idx;
 
-	for (ioapic_idx = nr_ioapics - 1; ioapic_idx >= 0; ioapic_idx--)
+	for (ioapic_idx = nr_ioapics - 1; ioapic_idx >= 0; ioapic_idx--) {
+		if (!ioapics[ioapic_idx].nr_registers)
+			continue;
+
 		resume_ioapic_id(ioapic_idx);
+	}
 
 	restore_ioapic_entries();
 }
@@ -3854,8 +3868,11 @@ static int __mp_find_ioapic(u32 gsi, bool quiet)
 	/* Find the IOAPIC that manages this GSI. */
 	for (i = 0; i < nr_ioapics; i++) {
 		struct mp_ioapic_gsi *gsi_cfg = mp_ioapic_gsi_routing(i);
-		if ((gsi >= gsi_cfg->gsi_base)
-		    && (gsi <= gsi_cfg->gsi_end))
+
+		if (!ioapics[i].nr_registers)
+			continue;
+
+		if ((gsi >= gsi_cfg->gsi_base) && (gsi <= gsi_cfg->gsi_end))
 			return i;
 	}
 
-- 
1.7.10.4