MSI: Remove dev->first_msi_irq

Now that we keep a list of msi descriptors, we don't need first_msi_irq
in the pci dev.

If we somehow have zero MSIs configured list_entry() will give us weird
oopes or nice memory corruption bugs. So be paranoid. Add BUG_ONs and also
a check in pci_msi_check_device() to make sure nvec > 0.

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

2 files changed, 20 insertions, 12 deletions

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 434c7182d926..7a44ba467481 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -269,7 +269,8 @@ static void __pci_restore_msix_state(struct pci_dev *dev)
                 msi_set_mask_bit(entry->irq, entry->msi_attrib.masked);
         }
 
-        entry = get_irq_msi(dev->first_msi_irq);
+        BUG_ON(list_empty(&dev->msi_list));
+        entry = list_entry(dev->msi_list.next, struct msi_desc, list);
         pos = entry->msi_attrib.pos;
         pci_read_config_word(dev, pos + PCI_MSIX_FLAGS, &control);
         control &= ~PCI_MSIX_FLAGS_MASKALL;
@@ -341,7 +342,6 @@ static int msi_capability_init(struct pci_dev *dev)
         }
         entry->irq = irq;
         list_add(&entry->list, &dev->msi_list);
-        dev->first_msi_irq = irq;
         set_irq_msi(irq, entry);
 
         /* Set MSI enabled bits  */
@@ -433,7 +433,6 @@ static int msix_capability_init(struct pci_dev *dev,
                         avail = -EBUSY;
                 return avail;
         }
-        dev->first_msi_irq = entries[0].vector;
         /* Set MSI-X enabled bits */
         pci_intx(dev, 0);               /* disable intx */
         msix_set_enable(dev, 1);
@@ -461,6 +460,14 @@ static int pci_msi_check_device(struct pci_dev* dev, int nvec, int type)
         if (!pci_msi_enable || !dev || dev->no_msi)
                 return -EINVAL;
 
+        /*
+         * You can't ask to have 0 or less MSIs configured.
+         *  a) it's stupid ..
+         *  b) the list manipulation code assumes nvec >= 1.
+         */
+        if (nvec < 1)
+                return -ERANGE;
+
         /* Any bridge which does NOT route MSI transactions from it's
          * secondary bus to it's primary bus must set NO_MSI flag on
          * the secondary pci_bus.
@@ -525,18 +532,17 @@ void pci_disable_msi(struct pci_dev* dev)
         pci_intx(dev, 1);               /* enable intx */
         dev->msi_enabled = 0;
 
-        entry = get_irq_msi(dev->first_msi_irq);
-        if (!entry || !entry->dev || entry->msi_attrib.type != PCI_CAP_ID_MSI) {
+        BUG_ON(list_empty(&dev->msi_list));
+        entry = list_entry(dev->msi_list.next, struct msi_desc, list);
+        if (!entry->dev || entry->msi_attrib.type != PCI_CAP_ID_MSI) {
                 return;
         }
 
         default_irq = entry->msi_attrib.default_irq;
-        msi_free_irq(dev, dev->first_msi_irq);
+        msi_free_irq(dev, entry->irq);
 
         /* Restore dev->irq to its default pin-assertion irq */
         dev->irq = default_irq;
-
-        dev->first_msi_irq = 0;
 }
 EXPORT_SYMBOL(pci_disable_msi);
 
@@ -634,7 +640,6 @@ static void msix_free_all_irqs(struct pci_dev *dev)
 
         list_for_each_entry(entry, &dev->msi_list, list)
                 msi_free_irq(dev, entry->irq);
-        dev->first_msi_irq = 0;
 }
 
 void pci_disable_msix(struct pci_dev* dev)
@@ -664,8 +669,12 @@ void msi_remove_pci_irq_vectors(struct pci_dev* dev)
         if (!pci_msi_enable || !dev)
                 return;
 
-        if (dev->msi_enabled)
-                msi_free_irq(dev, dev->first_msi_irq);
+        if (dev->msi_enabled) {
+                struct msi_desc *entry;
+                BUG_ON(list_empty(&dev->msi_list));
+                entry = list_entry(dev->msi_list.next, struct msi_desc, list);
+                msi_free_irq(dev, entry->irq);
+        }
 
         if (dev->msix_enabled)
                 msix_free_all_irqs(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d43097dc8672..a15569bf78b5 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -189,7 +189,6 @@ struct pci_dev {
         int rom_attr_enabled;           /* has display of the rom attribute been enabled? */
         struct bin_attribute *res_attr[DEVICE_COUNT_RESOURCE]; /* sysfs file for resources */
 #ifdef CONFIG_PCI_MSI
-        unsigned int first_msi_irq;
         struct list_head msi_list;
 #endif
 };