MSI: arch must connect the irq and the msi_desc

set_irq_msi() currently connects an irq_desc to an msi_desc. The archs call
it at some point in their setup routine, and then the generic code sets up the
reverse mapping from the msi_desc back to the irq.

set_irq_msi() should do both connections, making it the one and only call
required to connect an irq with it's MSI desc and vice versa.

The arch code MUST call set_irq_msi(), and it must do so only once it's sure
it's not going to fail the irq allocation.

Given that there's no need for the arch to return the irq anymore, the return
value from the arch setup routine just becomes 0 for success and anything else
for failure.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/i386/kernel/io_apic.c

@@ -2611,19 +2611,19 @@ int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
 	if (irq < 0)
 		return irq;
 
-	set_irq_msi(irq, desc);
 	ret = msi_compose_msg(dev, irq, &msg);
 	if (ret < 0) {
 		destroy_irq(irq);
 		return ret;
 	}
 
+	set_irq_msi(irq, desc);
 	write_msi_msg(irq, &msg);
 
 	set_irq_chip_and_handler_name(irq, &msi_chip, handle_edge_irq,
 				      "edge");
 
-	return irq;
+	return 0;
 }
 
 void arch_teardown_msi_irq(unsigned int irq)

arch/ia64/sn/kernel/msi_sn.c

@@ -87,7 +87,6 @@ int sn_setup_msi_irq(struct pci_dev *pdev, struct msi_desc *entry)
 	if (irq < 0)
 		return irq;
 
-	set_irq_msi(irq, entry);
 	/*
 	 * Set up the vector plumbing.  Let the prom (via sn_intr_alloc)
 	 * decide which cpu to direct this msi at by default.
@@ -144,10 +143,11 @@ int sn_setup_msi_irq(struct pci_dev *pdev, struct msi_desc *entry)
 	 */
 	msg.data = 0x100 + irq;
 
+	set_irq_msi(irq, entry);
 	write_msi_msg(irq, &msg);
 	set_irq_chip_and_handler(irq, &sn_msi_chip, handle_edge_irq);
 
-	return irq;
+	return 0;
 }
 
 #ifdef CONFIG_SMP

arch/sparc64/kernel/pci.c

@@ -1092,10 +1092,10 @@ int arch_setup_msi_irq(struct pci_dev *pdev, struct msi_desc *desc)
 		return -EINVAL;
 
 	err = p->setup_msi_irq(&virt_irq, pdev, desc);
-	if (err < 0)
+	if (err)
 		return err;
 
-	return virt_irq;
+	return 0;
 }
 
 void arch_teardown_msi_irq(unsigned int virt_irq)

arch/sparc64/kernel/pci_sun4v.c

@@ -1169,8 +1169,6 @@ static int pci_sun4v_setup_msi_irq(unsigned int *virt_irq_p,
 	if (!devino)
 		goto out_err;
 
-	set_irq_msi(*virt_irq_p, entry);
-
 	msiqid = ((devino - pbm->msiq_first_devino) +
 		  pbm->msiq_first);
 
@@ -1204,6 +1202,8 @@ static int pci_sun4v_setup_msi_irq(unsigned int *virt_irq_p,
 		msg.address_lo = pbm->msi32_start;
 	}
 	msg.data = msi_num;
+
+	set_irq_msi(*virt_irq_p, entry);
 	write_msi_msg(*virt_irq_p, &msg);
 
 	irq_install_pre_handler(*virt_irq_p,

arch/x86_64/kernel/io_apic.c

@@ -1983,18 +1983,18 @@ int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
 	if (irq < 0)
 		return irq;
 
-	set_irq_msi(irq, desc);
 	ret = msi_compose_msg(dev, irq, &msg);
 	if (ret < 0) {
 		destroy_irq(irq);
 		return ret;
 	}
 
+	set_irq_msi(irq, desc);
 	write_msi_msg(irq, &msg);
 
 	set_irq_chip_and_handler_name(irq, &msi_chip, handle_edge_irq, "edge");
 
-	return irq;
+	return 0;
 }
 
 void arch_teardown_msi_irq(unsigned int irq)

drivers/pci/msi.c

@@ -297,7 +297,7 @@ void pci_restore_msi_state(struct pci_dev *dev)
 static int msi_capability_init(struct pci_dev *dev)
 {
 	struct msi_desc *entry;
-	int pos, irq;
+	int pos, ret;
 	u16 control;
 
 	msi_set_enable(dev, 0);	/* Ensure msi is disabled as I set it up */
@@ -335,21 +335,19 @@ static int msi_capability_init(struct pci_dev *dev)
 			maskbits);
 	}
 	/* Configure MSI capability structure */
-	irq = arch_setup_msi_irq(dev, entry);
-	if (irq < 0) {
+	ret = arch_setup_msi_irq(dev, entry);
+	if (ret) {
 		kfree(entry);
-		return irq;
+		return ret;
 	}
-	entry->irq = irq;
 	list_add(&entry->list, &dev->msi_list);
-	set_irq_msi(irq, entry);
 
 	/* Set MSI enabled bits	 */
 	pci_intx(dev, 0);		/* disable intx */
 	msi_set_enable(dev, 1);
 	dev->msi_enabled = 1;
 
-	dev->irq = irq;
+	dev->irq = entry->irq;
 	return 0;
 }
 
@@ -367,7 +365,7 @@ static int msix_capability_init(struct pci_dev *dev,
 				struct msix_entry *entries, int nvec)
 {
 	struct msi_desc *entry;
-	int irq, pos, i, j, nr_entries;
+	int irq, pos, i, j, nr_entries, ret;
 	unsigned long phys_addr;
 	u32 table_offset;
  	u16 control;
@@ -407,16 +405,13 @@ static int msix_capability_init(struct pci_dev *dev,
 		entry->mask_base = base;
 
 		/* Configure MSI-X capability structure */
-		irq = arch_setup_msi_irq(dev, entry);
-		if (irq < 0) {
+		ret = arch_setup_msi_irq(dev, entry);
+		if (ret) {
 			kfree(entry);
 			break;
 		}
-		entry->irq = irq;
- 		entries[i].vector = irq;
+ 		entries[i].vector = entry->irq;
 		list_add(&entry->list, &dev->msi_list);
-
-		set_irq_msi(irq, entry);
 	}
 	if (i != nvec) {
 		int avail = i - 1;

kernel/irq/chip.c

@@ -11,6 +11,7 @@
  */
 
 #include <linux/irq.h>
+#include <linux/msi.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
@@ -185,6 +186,8 @@ int set_irq_msi(unsigned int irq, struct msi_desc *entry)
 	desc = irq_desc + irq;
 	spin_lock_irqsave(&desc->lock, flags);
 	desc->msi_desc = entry;
+	if (entry)
+		entry->irq = irq;
 	spin_unlock_irqrestore(&desc->lock, flags);
 	return 0;
 }