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authorEric W. Biederman <ebiederm@xmission.com>2007-02-23 04:40:58 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-26 10:34:08 -0800
commit610142927b5bc149da92b03c7ab08b8b5f205b74 (patch)
tree600c115072fc5f28c07dddfbe52f0dcf376d8504 /arch/x86_64
parentbc5e81a1519abc69472bb67deace7bb1ac09d65a (diff)
[PATCH] x86_64 irq: Safely cleanup an irq after moving it.
The problem: After moving an interrupt when is it safe to teardown the data structures for receiving the interrupt at the old location? With a normal pci device it is possible to issue a read to a device to flush all posted writes. This does not work for the oldest ioapics because they are on a 3-wire apic bus which is a completely different data path. For some more modern ioapics when everything is using front side bus delivery you can flush interrupts by simply issuing a read to the ioapic. For other modern ioapics emperical testing has shown that this does not work. So it appears the only reliable way to know the last of the irqs from an ioapic have been received from before the ioapic was reprogrammed is to received the first irq from the ioapic from after it was reprogrammed. Once we know the last irq message has been received from an ioapic into a local apic we then need to know that irq message has been processed through the local apics. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86_64')
-rw-r--r--arch/x86_64/kernel/entry.S3
-rw-r--r--arch/x86_64/kernel/i8259.c6
-rw-r--r--arch/x86_64/kernel/io_apic.c78
3 files changed, 81 insertions, 6 deletions
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 9f5dac64aa8f..ed4350ced3d0 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -675,6 +675,9 @@ END(invalidate_interrupt\num)
ENTRY(call_function_interrupt)
apicinterrupt CALL_FUNCTION_VECTOR,smp_call_function_interrupt
END(call_function_interrupt)
+ENTRY(irq_move_cleanup_interrupt)
+ apicinterrupt IRQ_MOVE_CLEANUP_VECTOR,smp_irq_move_cleanup_interrupt
+END(irq_move_cleanup_interrupt)
#endif
ENTRY(apic_timer_interrupt)
diff --git a/arch/x86_64/kernel/i8259.c b/arch/x86_64/kernel/i8259.c
index 45d85630196a..21d95b747437 100644
--- a/arch/x86_64/kernel/i8259.c
+++ b/arch/x86_64/kernel/i8259.c
@@ -450,6 +450,7 @@ void spurious_interrupt(void);
void error_interrupt(void);
void reschedule_interrupt(void);
void call_function_interrupt(void);
+void irq_move_cleanup_interrupt(void);
void invalidate_interrupt0(void);
void invalidate_interrupt1(void);
void invalidate_interrupt2(void);
@@ -537,7 +538,10 @@ void __init init_IRQ(void)
/* IPI for generic function call */
set_intr_gate(CALL_FUNCTION_VECTOR, call_function_interrupt);
-#endif
+
+ /* Low priority IPI to cleanup after moving an irq */
+ set_intr_gate(IRQ_MOVE_CLEANUP_VECTOR, irq_move_cleanup_interrupt);
+#endif
set_intr_gate(THERMAL_APIC_VECTOR, thermal_interrupt);
set_intr_gate(THRESHOLD_APIC_VECTOR, threshold_interrupt);
diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c
index 8dede0bd2267..48593f6b708f 100644
--- a/arch/x86_64/kernel/io_apic.c
+++ b/arch/x86_64/kernel/io_apic.c
@@ -36,6 +36,7 @@
#include <acpi/acpi_bus.h>
#endif
+#include <asm/idle.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/desc.h>
@@ -49,7 +50,10 @@
struct irq_cfg {
cpumask_t domain;
+ cpumask_t old_domain;
+ unsigned move_cleanup_count;
u8 vector;
+ u8 move_in_progress : 1;
};
/* irq_cfg is indexed by the sum of all RTEs in all I/O APICs. */
@@ -652,7 +656,6 @@ static int __assign_irq_vector(int irq, cpumask_t mask)
* 0x80, because int 0x80 is hm, kind of importantish. ;)
*/
static int current_vector = FIRST_DEVICE_VECTOR, current_offset = 0;
- cpumask_t old_mask = CPU_MASK_NONE;
unsigned int old_vector;
int cpu;
struct irq_cfg *cfg;
@@ -663,18 +666,20 @@ static int __assign_irq_vector(int irq, cpumask_t mask)
/* Only try and allocate irqs on cpus that are present */
cpus_and(mask, mask, cpu_online_map);
+ if ((cfg->move_in_progress) || cfg->move_cleanup_count)
+ return -EBUSY;
+
old_vector = cfg->vector;
if (old_vector) {
cpumask_t tmp;
cpus_and(tmp, cfg->domain, mask);
if (!cpus_empty(tmp))
return 0;
- cpus_and(old_mask, cfg->domain, cpu_online_map);
}
for_each_cpu_mask(cpu, mask) {
cpumask_t domain, new_mask;
- int new_cpu, old_cpu;
+ int new_cpu;
int vector, offset;
domain = vector_allocation_domain(cpu);
@@ -699,8 +704,10 @@ next:
/* Found one! */
current_vector = vector;
current_offset = offset;
- for_each_cpu_mask(old_cpu, old_mask)
- per_cpu(vector_irq, old_cpu)[old_vector] = -1;
+ if (old_vector) {
+ cfg->move_in_progress = 1;
+ cfg->old_domain = cfg->domain;
+ }
for_each_cpu_mask(new_cpu, new_mask)
per_cpu(vector_irq, new_cpu)[vector] = irq;
cfg->vector = vector;
@@ -1360,8 +1367,68 @@ static int ioapic_retrigger_irq(unsigned int irq)
* races.
*/
+#ifdef CONFIG_SMP
+asmlinkage void smp_irq_move_cleanup_interrupt(void)
+{
+ unsigned vector, me;
+ ack_APIC_irq();
+ exit_idle();
+ irq_enter();
+
+ me = smp_processor_id();
+ for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
+ unsigned int irq;
+ struct irq_desc *desc;
+ struct irq_cfg *cfg;
+ irq = __get_cpu_var(vector_irq)[vector];
+ if (irq >= NR_IRQS)
+ continue;
+
+ desc = irq_desc + irq;
+ cfg = irq_cfg + irq;
+ spin_lock(&desc->lock);
+ if (!cfg->move_cleanup_count)
+ goto unlock;
+
+ if ((vector == cfg->vector) && cpu_isset(me, cfg->domain))
+ goto unlock;
+
+ __get_cpu_var(vector_irq)[vector] = -1;
+ cfg->move_cleanup_count--;
+unlock:
+ spin_unlock(&desc->lock);
+ }
+
+ irq_exit();
+}
+
+static void irq_complete_move(unsigned int irq)
+{
+ struct irq_cfg *cfg = irq_cfg + irq;
+ unsigned vector, me;
+
+ if (likely(!cfg->move_in_progress))
+ return;
+
+ vector = ~get_irq_regs()->orig_rax;
+ me = smp_processor_id();
+ if ((vector == cfg->vector) &&
+ cpu_isset(smp_processor_id(), cfg->domain)) {
+ cpumask_t cleanup_mask;
+
+ cpus_and(cleanup_mask, cfg->old_domain, cpu_online_map);
+ cfg->move_cleanup_count = cpus_weight(cleanup_mask);
+ send_IPI_mask(cleanup_mask, IRQ_MOVE_CLEANUP_VECTOR);
+ cfg->move_in_progress = 0;
+ }
+}
+#else
+static inline void irq_complete_move(unsigned int irq) {}
+#endif
+
static void ack_apic_edge(unsigned int irq)
{
+ irq_complete_move(irq);
move_native_irq(irq);
ack_APIC_irq();
}
@@ -1370,6 +1437,7 @@ static void ack_apic_level(unsigned int irq)
{
int do_unmask_irq = 0;
+ irq_complete_move(irq);
#if defined(CONFIG_GENERIC_PENDING_IRQ) || defined(CONFIG_IRQBALANCE)
/* If we are moving the irq we need to mask it */
if (unlikely(irq_desc[irq].status & IRQ_MOVE_PENDING)) {