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Message-ID: <1339108459.28766.112.camel@sbsiddha-desk.sc.intel.com>
Date:	Thu, 07 Jun 2012 15:34:19 -0700
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	Ingo Molnar <mingo@...nel.org>, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	joerg.roedel@....com, Sam Ravnborg <sam@...nborg.org>
Subject: Re: [patch] irq: use config_enabled(SMP) checks to cleanup
 irq_set_affinity() for UP

On Thu, 2012-06-07 at 09:03 -0400, Paul Gortmaker wrote:
> On 12-06-06 07:29 PM, Suresh Siddha wrote:
> > On Ingo's request, re-basing the previous version
> > (http://marc.info/?l=linux-kernel&m=133667389223282) to the latest -tip
> > tree. Thanks.
> > ---
> > From: Suresh Siddha <suresh.b.siddha@...el.com>
> > Subject: irq: use config_enabled(CONFIG_SMP) checks to cleanup irq_set_affinity() for UP
> > 
> > Use config_enabled(CONFIG_SMP) checks for cleaning up the ifdef CONFIG_SMP
> > around irq_set_affinity routines in io_apic and irq_remapping subsystems.
> > 
> > Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
> > ---
> >  arch/x86/kernel/apic/io_apic.c      |  173 +++++++++++++++++------------------
> 
> What was the necessity of the giant code block move here?

Patch was moving the SMP affinity routines out of the existing "#ifdef
CONFIG_SMP" section and adding config_enabled(CONFIG_SMP) inside those
routines, making those routines simple null stubs for !SMP and retaining
those routines with no runtime checks for SMP kernels.

> It wasn't obvious to me, and it isn't called out in the
> commit log.  Presumably some used before defined issue, but
> it would be nice to have that called out, so a person isn't
> wondering if instead it was an offhand error.

Updated with more elaborate changelog!
---
From: Suresh Siddha <suresh.b.siddha@...el.com>
Subject: irq: use config_enabled(CONFIG_SMP) checks to cleanup irq_set_affinity() for UP

Move the set_affinity routines out of the #ifdef CONFIG_SMP sections and
use config_enabled(CONFIG_SMP) checks inside those routines. Thus
making those routines simple null stubs for !CONFIG_SMP and retaining those
routines with no additional runtime overhead for CONFIG_SMP kernels.

Cleans up the ifdef CONFIG_SMP in and around routines related to
irq_set_affinity in io_apic and irq_remapping subsystems.

Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
---
 arch/x86/kernel/apic/io_apic.c      |  173 +++++++++++++++++------------------
 drivers/iommu/intel_irq_remapping.c |    7 +-
 drivers/iommu/irq_remapping.c       |    5 +-
 drivers/iommu/irq_remapping.h       |    2 -
 include/linux/irq.h                 |    2 -
 5 files changed, 88 insertions(+), 101 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 9a71f21..f246b78 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2206,72 +2206,6 @@ void send_cleanup_vector(struct irq_cfg *cfg)
 	cfg->move_in_progress = 0;
 }
 
-static void __target_IO_APIC_irq(unsigned int irq, unsigned int dest, struct irq_cfg *cfg)
-{
-	int apic, pin;
-	struct irq_pin_list *entry;
-	u8 vector = cfg->vector;
-
-	for_each_irq_pin(entry, cfg->irq_2_pin) {
-		unsigned int reg;
-
-		apic = entry->apic;
-		pin = entry->pin;
-		/*
-		 * With interrupt-remapping, destination information comes
-		 * from interrupt-remapping table entry.
-		 */
-		if (!irq_remapped(cfg))
-			io_apic_write(apic, 0x11 + pin*2, dest);
-		reg = io_apic_read(apic, 0x10 + pin*2);
-		reg &= ~IO_APIC_REDIR_VECTOR_MASK;
-		reg |= vector;
-		io_apic_modify(apic, 0x10 + pin*2, reg);
-	}
-}
-
-/*
- * Either sets data->affinity to a valid value, and returns
- * ->cpu_mask_to_apicid of that in dest_id, or returns -1 and
- * leaves data->affinity untouched.
- */
-int __ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
-			  unsigned int *dest_id)
-{
-	struct irq_cfg *cfg = data->chip_data;
-
-	if (!cpumask_intersects(mask, cpu_online_mask))
-		return -1;
-
-	if (assign_irq_vector(data->irq, data->chip_data, mask))
-		return -1;
-
-	cpumask_copy(data->affinity, mask);
-
-	*dest_id = apic->cpu_mask_to_apicid_and(mask, cfg->domain);
-	return 0;
-}
-
-static int
-ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
-		    bool force)
-{
-	unsigned int dest, irq = data->irq;
-	unsigned long flags;
-	int ret;
-
-	raw_spin_lock_irqsave(&ioapic_lock, flags);
-	ret = __ioapic_set_affinity(data, mask, &dest);
-	if (!ret) {
-		/* Only the high 8 bits are valid. */
-		dest = SET_APIC_LOGICAL_ID(dest);
-		__target_IO_APIC_irq(irq, dest, data->chip_data);
-		ret = IRQ_SET_MASK_OK_NOCOPY;
-	}
-	raw_spin_unlock_irqrestore(&ioapic_lock, flags);
-	return ret;
-}
-
 asmlinkage void smp_irq_move_cleanup_interrupt(void)
 {
 	unsigned vector, me;
@@ -2359,6 +2293,77 @@ void irq_force_complete_move(int irq)
 static inline void irq_complete_move(struct irq_cfg *cfg) { }
 #endif
 
+static void __target_IO_APIC_irq(unsigned int irq, unsigned int dest, struct irq_cfg *cfg)
+{
+	int apic, pin;
+	struct irq_pin_list *entry;
+	u8 vector = cfg->vector;
+
+	for_each_irq_pin(entry, cfg->irq_2_pin) {
+		unsigned int reg;
+
+		apic = entry->apic;
+		pin = entry->pin;
+		/*
+		 * With interrupt-remapping, destination information comes
+		 * from interrupt-remapping table entry.
+		 */
+		if (!irq_remapped(cfg))
+			io_apic_write(apic, 0x11 + pin*2, dest);
+		reg = io_apic_read(apic, 0x10 + pin*2);
+		reg &= ~IO_APIC_REDIR_VECTOR_MASK;
+		reg |= vector;
+		io_apic_modify(apic, 0x10 + pin*2, reg);
+	}
+}
+
+/*
+ * Either sets data->affinity to a valid value, and returns
+ * ->cpu_mask_to_apicid of that in dest_id, or returns -1 and
+ * leaves data->affinity untouched.
+ */
+int __ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
+			  unsigned int *dest_id)
+{
+	struct irq_cfg *cfg = data->chip_data;
+
+	if (!config_enabled(CONFIG_SMP))
+		return -1;
+
+	if (!cpumask_intersects(mask, cpu_online_mask))
+		return -1;
+
+	if (assign_irq_vector(data->irq, data->chip_data, mask))
+		return -1;
+
+	cpumask_copy(data->affinity, mask);
+
+	*dest_id = apic->cpu_mask_to_apicid_and(mask, cfg->domain);
+	return 0;
+}
+
+static int
+ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
+		    bool force)
+{
+	unsigned int dest, irq = data->irq;
+	unsigned long flags;
+	int ret;
+
+	if (!config_enabled(CONFIG_SMP))
+		return -1;
+
+	raw_spin_lock_irqsave(&ioapic_lock, flags);
+	ret = __ioapic_set_affinity(data, mask, &dest);
+	if (!ret) {
+		/* Only the high 8 bits are valid. */
+		dest = SET_APIC_LOGICAL_ID(dest);
+		__target_IO_APIC_irq(irq, dest, data->chip_data);
+	}
+	raw_spin_unlock_irqrestore(&ioapic_lock, flags);
+	return ret;
+}
+
 static void ack_apic_edge(struct irq_data *data)
 {
 	irq_complete_move(data->chip_data);
@@ -2538,9 +2543,7 @@ static void irq_remap_modify_chip_defaults(struct irq_chip *chip)
 	chip->irq_ack = ir_ack_apic_edge;
 	chip->irq_eoi = ir_ack_apic_level;
 
-#ifdef CONFIG_SMP
 	chip->irq_set_affinity = set_remapped_irq_affinity;
-#endif
 }
 #endif /* CONFIG_IRQ_REMAP */
 
@@ -2551,9 +2554,7 @@ static struct irq_chip ioapic_chip __read_mostly = {
 	.irq_unmask		= unmask_ioapic_irq,
 	.irq_ack		= ack_apic_edge,
 	.irq_eoi		= ack_apic_level,
-#ifdef CONFIG_SMP
 	.irq_set_affinity	= ioapic_set_affinity,
-#endif
 	.irq_retrigger		= ioapic_retrigger_irq,
 };
 
@@ -3069,7 +3070,6 @@ static int msi_compose_msg(struct pci_dev *pdev, unsigned int irq,
 	return err;
 }
 
-#ifdef CONFIG_SMP
 static int
 msi_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
 {
@@ -3077,6 +3077,9 @@ msi_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
 	struct msi_msg msg;
 	unsigned int dest;
 
+	if (!config_enabled(CONFIG_SMP))
+		return -1;
+
 	if (__ioapic_set_affinity(data, mask, &dest))
 		return -1;
 
@@ -3091,7 +3094,6 @@ msi_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
 
 	return IRQ_SET_MASK_OK_NOCOPY;
 }
-#endif /* CONFIG_SMP */
 
 /*
  * IRQ Chip for MSI PCI/PCI-X/PCI-Express Devices,
@@ -3102,9 +3104,7 @@ static struct irq_chip msi_chip = {
 	.irq_unmask		= unmask_msi_irq,
 	.irq_mask		= mask_msi_irq,
 	.irq_ack		= ack_apic_edge,
-#ifdef CONFIG_SMP
 	.irq_set_affinity	= msi_set_affinity,
-#endif
 	.irq_retrigger		= ioapic_retrigger_irq,
 };
 
@@ -3189,7 +3189,6 @@ void native_teardown_msi_irq(unsigned int irq)
 }
 
 #ifdef CONFIG_DMAR_TABLE
-#ifdef CONFIG_SMP
 static int
 dmar_msi_set_affinity(struct irq_data *data, const struct cpumask *mask,
 		      bool force)
@@ -3198,6 +3197,9 @@ dmar_msi_set_affinity(struct irq_data *data, const struct cpumask *mask,
 	unsigned int dest, irq = data->irq;
 	struct msi_msg msg;
 
+	if (!config_enabled(CONFIG_SMP))
+		return -1;
+
 	if (__ioapic_set_affinity(data, mask, &dest))
 		return -1;
 
@@ -3214,16 +3216,12 @@ dmar_msi_set_affinity(struct irq_data *data, const struct cpumask *mask,
 	return IRQ_SET_MASK_OK_NOCOPY;
 }
 
-#endif /* CONFIG_SMP */
-
 static struct irq_chip dmar_msi_type = {
 	.name			= "DMAR_MSI",
 	.irq_unmask		= dmar_msi_unmask,
 	.irq_mask		= dmar_msi_mask,
 	.irq_ack		= ack_apic_edge,
-#ifdef CONFIG_SMP
 	.irq_set_affinity	= dmar_msi_set_affinity,
-#endif
 	.irq_retrigger		= ioapic_retrigger_irq,
 };
 
@@ -3244,7 +3242,6 @@ int arch_setup_dmar_msi(unsigned int irq)
 
 #ifdef CONFIG_HPET_TIMER
 
-#ifdef CONFIG_SMP
 static int hpet_msi_set_affinity(struct irq_data *data,
 				 const struct cpumask *mask, bool force)
 {
@@ -3252,6 +3249,9 @@ static int hpet_msi_set_affinity(struct irq_data *data,
 	struct msi_msg msg;
 	unsigned int dest;
 
+	if (!config_enabled(CONFIG_SMP))
+		return -1;
+
 	if (__ioapic_set_affinity(data, mask, &dest))
 		return -1;
 
@@ -3267,16 +3267,12 @@ static int hpet_msi_set_affinity(struct irq_data *data,
 	return IRQ_SET_MASK_OK_NOCOPY;
 }
 
-#endif /* CONFIG_SMP */
-
 static struct irq_chip hpet_msi_type = {
 	.name = "HPET_MSI",
 	.irq_unmask = hpet_msi_unmask,
 	.irq_mask = hpet_msi_mask,
 	.irq_ack = ack_apic_edge,
-#ifdef CONFIG_SMP
 	.irq_set_affinity = hpet_msi_set_affinity,
-#endif
 	.irq_retrigger = ioapic_retrigger_irq,
 };
 
@@ -3311,8 +3307,6 @@ int arch_setup_hpet_msi(unsigned int irq, unsigned int id)
  */
 #ifdef CONFIG_HT_IRQ
 
-#ifdef CONFIG_SMP
-
 static void target_ht_irq(unsigned int irq, unsigned int dest, u8 vector)
 {
 	struct ht_irq_msg msg;
@@ -3333,6 +3327,9 @@ ht_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
 	struct irq_cfg *cfg = data->chip_data;
 	unsigned int dest;
 
+	if (!config_enabled(CONFIG_SMP))
+		return -1;
+
 	if (__ioapic_set_affinity(data, mask, &dest))
 		return -1;
 
@@ -3340,16 +3337,12 @@ ht_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
 	return IRQ_SET_MASK_OK_NOCOPY;
 }
 
-#endif
-
 static struct irq_chip ht_irq_chip = {
 	.name			= "PCI-HT",
 	.irq_mask		= mask_ht_irq,
 	.irq_unmask		= unmask_ht_irq,
 	.irq_ack		= ack_apic_edge,
-#ifdef CONFIG_SMP
 	.irq_set_affinity	= ht_set_affinity,
-#endif
 	.irq_retrigger		= ioapic_retrigger_irq,
 };
 
diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 6d34706..b3481cf 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -902,7 +902,6 @@ static int intel_setup_ioapic_entry(int irq,
 	return 0;
 }
 
-#ifdef CONFIG_SMP
 /*
  * Migrate the IO-APIC irq in the presence of intr-remapping.
  *
@@ -925,6 +924,9 @@ intel_ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
 	unsigned int dest, irq = data->irq;
 	struct irte irte;
 
+	if (!config_enabled(CONFIG_SMP))
+		return -EINVAL;
+
 	if (!cpumask_intersects(mask, cpu_online_mask))
 		return -EINVAL;
 
@@ -956,7 +958,6 @@ intel_ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
 	cpumask_copy(data->affinity, mask);
 	return 0;
 }
-#endif
 
 static void intel_compose_msi_msg(struct pci_dev *pdev,
 				  unsigned int irq, unsigned int dest,
@@ -1058,9 +1059,7 @@ struct irq_remap_ops intel_irq_remap_ops = {
 	.reenable		= reenable_irq_remapping,
 	.enable_faulting	= enable_drhd_fault_handling,
 	.setup_ioapic_entry	= intel_setup_ioapic_entry,
-#ifdef CONFIG_SMP
 	.set_affinity		= intel_ioapic_set_affinity,
-#endif
 	.free_irq		= free_irte,
 	.compose_msi_msg	= intel_compose_msi_msg,
 	.msi_alloc_irq		= intel_msi_alloc_irq,
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 40cda8e..1d29b1c 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -111,16 +111,15 @@ int setup_ioapic_remapped_entry(int irq,
 					     vector, attr);
 }
 
-#ifdef CONFIG_SMP
 int set_remapped_irq_affinity(struct irq_data *data, const struct cpumask *mask,
 			      bool force)
 {
-	if (!remap_ops || !remap_ops->set_affinity)
+	if (!config_enabled(CONFIG_SMP) || !remap_ops ||
+	    !remap_ops->set_affinity)
 		return 0;
 
 	return remap_ops->set_affinity(data, mask, force);
 }
-#endif
 
 void free_remapped_irq(int irq)
 {
diff --git a/drivers/iommu/irq_remapping.h b/drivers/iommu/irq_remapping.h
index be9d729..b12974c 100644
--- a/drivers/iommu/irq_remapping.h
+++ b/drivers/iommu/irq_remapping.h
@@ -59,11 +59,9 @@ struct irq_remap_ops {
 				  unsigned int, int,
 				  struct io_apic_irq_attr *);
 
-#ifdef CONFIG_SMP
 	/* Set the CPU affinity of a remapped interrupt */
 	int (*set_affinity)(struct irq_data *data, const struct cpumask *mask,
 			    bool force);
-#endif
 
 	/* Free an IRQ */
 	int (*free_irq)(int);
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 61f5cec..47a937c 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -150,9 +150,7 @@ struct irq_data {
 	void			*handler_data;
 	void			*chip_data;
 	struct msi_desc		*msi_desc;
-#ifdef CONFIG_SMP
 	cpumask_var_t		affinity;
-#endif
 };
 
 /*


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