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Subject[tip:x86/apic] x86, irq, ACPI: Introduce a mutex to protect IOAPIC operations from hotplug
Commit-ID:  bca74a854c10cbbbf13690e92704e81f6afdb697
Gitweb: http://git.kernel.org/tip/bca74a854c10cbbbf13690e92704e81f6afdb697
Author: Jiang Liu <jiang.liu@linux.intel.com>
AuthorDate: Sun, 2 Nov 2014 14:04:29 +0800
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 3 Nov 2014 11:56:08 +0100

x86, irq, ACPI: Introduce a mutex to protect IOAPIC operations from hotplug

We are going to support ACPI based IOAPIC hotplug, so introduce a mutex
to protect IOAPIC data structures from IOAPIC hotplug. We choose to
serialize in ACPI instead of in the IOAPIC core because:

1) currently we only plan to support ACPI based IOAPIC hotplug
2) it's much more cleaner and easier
3) It does't affect IOAPIC discovered by devicetree, SFI and mpparse.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Link: http://lkml.kernel.org/r/1414908273-7552-15-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/acpi/boot.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index a142e77..1a2d9d4 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -76,6 +76,19 @@ int acpi_fix_pin2_polarity __initdata;
static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
#endif

+/*
+ * Locks related to IOAPIC hotplug
+ * Hotplug side:
+ * ->device_hotplug_lock
+ * ->acpi_ioapic_lock
+ * ->ioapic_lock
+ * Interrupt mapping side:
+ * ->acpi_ioapic_lock
+ * ->ioapic_mutex
+ * ->ioapic_lock
+ */
+static DEFINE_MUTEX(acpi_ioapic_lock);
+
/* --------------------------------------------------------------------------
Boot-time Configuration
-------------------------------------------------------------------------- */
@@ -609,8 +622,10 @@ int acpi_gsi_to_irq(u32 gsi, unsigned int *irqp)
if (acpi_irq_model == ACPI_IRQ_MODEL_PIC) {
*irqp = gsi;
} else {
+ mutex_lock(&acpi_ioapic_lock);
irq = mp_map_gsi_to_irq(gsi,
IOAPIC_MAP_ALLOC | IOAPIC_MAP_CHECK);
+ mutex_unlock(&acpi_ioapic_lock);
if (irq < 0)
return -1;
*irqp = irq;
@@ -650,7 +665,9 @@ static int acpi_register_gsi_ioapic(struct device *dev, u32 gsi,
int irq = gsi;

#ifdef CONFIG_X86_IO_APIC
+ mutex_lock(&acpi_ioapic_lock);
irq = mp_register_gsi(dev, gsi, trigger, polarity);
+ mutex_unlock(&acpi_ioapic_lock);
#endif

return irq;
@@ -659,7 +676,9 @@ static int acpi_register_gsi_ioapic(struct device *dev, u32 gsi,
static void acpi_unregister_gsi_ioapic(u32 gsi)
{
#ifdef CONFIG_X86_IO_APIC
+ mutex_lock(&acpi_ioapic_lock);
mp_unregister_gsi(gsi);
+ mutex_unlock(&acpi_ioapic_lock);
#endif
}

@@ -1185,7 +1204,9 @@ static void __init acpi_process_madt(void)
/*
* Parse MADT IO-APIC entries
*/
+ mutex_lock(&acpi_ioapic_lock);
error = acpi_parse_madt_ioapic_entries();
+ mutex_unlock(&acpi_ioapic_lock);
if (!error) {
acpi_set_irq_model_ioapic();


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