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Message-ID: <20120320141935.GA24806@dhcp-26-207.brq.redhat.com>
Date: Tue, 20 Mar 2012 15:19:36 +0100
From: Alexander Gordeev <agordeev@...hat.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH V2] x86: io_apic: Move and reenable irq only when
CONFIG_GENERIC_PENDING_IRQ=y
When CONFIG_GENERIC_PENDING_IRQ=n irq move and reenable code is never
get executed, nor do_unmask_irq variable updates its init value. Move
the code under CONFIG_GENERIC_PENDING_IRQ macro.
Signed-off-by: Alexander Gordeev <agordeev@...hat.com>
---
arch/x86/kernel/apic/io_apic.c | 101 ++++++++++++++++++++++++----------------
1 files changed, 61 insertions(+), 40 deletions(-)
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index fb07275..8cd6360 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2512,21 +2512,73 @@ static void ack_apic_edge(struct irq_data *data)
atomic_t irq_mis_count;
-static void ack_apic_level(struct irq_data *data)
-{
- struct irq_cfg *cfg = data->chip_data;
- int i, do_unmask_irq = 0, irq = data->irq;
- unsigned long v;
-
- irq_complete_move(cfg);
#ifdef CONFIG_GENERIC_PENDING_IRQ
+static inline bool ioapic_irqd_mask(struct irq_data *data, struct irq_cfg *cfg)
+{
/* If we are moving the irq we need to mask it */
if (unlikely(irqd_is_setaffinity_pending(data))) {
- do_unmask_irq = 1;
mask_ioapic(cfg);
+ return true;
}
+ return false;
+}
+
+static inline void ioapic_irqd_unmask(struct irq_data *data,
+ struct irq_cfg *cfg, bool masked)
+{
+ if (unlikely(masked)) {
+ /* Only migrate the irq if the ack has been received.
+ *
+ * On rare occasions the broadcast level triggered ack gets
+ * delayed going to ioapics, and if we reprogram the
+ * vector while Remote IRR is still set the irq will never
+ * fire again.
+ *
+ * To prevent this scenario we read the Remote IRR bit
+ * of the ioapic. This has two effects.
+ * - On any sane system the read of the ioapic will
+ * flush writes (and acks) going to the ioapic from
+ * this cpu.
+ * - We get to see if the ACK has actually been delivered.
+ *
+ * Based on failed experiments of reprogramming the
+ * ioapic entry from outside of irq context starting
+ * with masking the ioapic entry and then polling until
+ * Remote IRR was clear before reprogramming the
+ * ioapic I don't trust the Remote IRR bit to be
+ * completey accurate.
+ *
+ * However there appears to be no other way to plug
+ * this race, so if the Remote IRR bit is not
+ * accurate and is causing problems then it is a hardware bug
+ * and you can go talk to the chipset vendor about it.
+ */
+ if (!io_apic_level_ack_pending(cfg))
+ irq_move_masked_irq(data);
+ unmask_ioapic(cfg);
+ }
+}
+#else
+static inline bool ioapic_irqd_mask(struct irq_data *data, struct irq_cfg *cfg)
+{
+ return false;
+}
+static inline void ioapic_irqd_unmask(struct irq_data *data,
+ struct irq_cfg *cfg, bool masked)
+{
+}
#endif
+static void ack_apic_level(struct irq_data *data)
+{
+ struct irq_cfg *cfg = data->chip_data;
+ int i, irq = data->irq;
+ unsigned long v;
+ bool masked;
+
+ irq_complete_move(cfg);
+ masked = ioapic_irqd_mask(data, cfg);
+
/*
* It appears there is an erratum which affects at least version 0x11
* of I/O APIC (that's the 82093AA and cores integrated into various
@@ -2581,38 +2633,7 @@ static void ack_apic_level(struct irq_data *data)
eoi_ioapic_irq(irq, cfg);
}
- /* Now we can move and renable the irq */
- if (unlikely(do_unmask_irq)) {
- /* Only migrate the irq if the ack has been received.
- *
- * On rare occasions the broadcast level triggered ack gets
- * delayed going to ioapics, and if we reprogram the
- * vector while Remote IRR is still set the irq will never
- * fire again.
- *
- * To prevent this scenario we read the Remote IRR bit
- * of the ioapic. This has two effects.
- * - On any sane system the read of the ioapic will
- * flush writes (and acks) going to the ioapic from
- * this cpu.
- * - We get to see if the ACK has actually been delivered.
- *
- * Based on failed experiments of reprogramming the
- * ioapic entry from outside of irq context starting
- * with masking the ioapic entry and then polling until
- * Remote IRR was clear before reprogramming the
- * ioapic I don't trust the Remote IRR bit to be
- * completey accurate.
- *
- * However there appears to be no other way to plug
- * this race, so if the Remote IRR bit is not
- * accurate and is causing problems then it is a hardware bug
- * and you can go talk to the chipset vendor about it.
- */
- if (!io_apic_level_ack_pending(cfg))
- irq_move_masked_irq(data);
- unmask_ioapic(cfg);
- }
+ ioapic_irqd_unmask(data, cfg, masked);
}
#ifdef CONFIG_IRQ_REMAP
--
1.7.7.6
--
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