powerpc/eeh: Introdce flag to protect sysfs

The patch introduces flag EEH_DEV_SYSFS to keep track that the sysfs
entries for the corresponding EEH device (then PCI device) has been
added or removed, in order to avoid race condition.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

5 files changed, 22 insertions, 4 deletions

diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
index 4199d9943277..d3e5e9bc8f94 100644
--- a/arch/powerpc/include/asm/eeh.h
+++ b/arch/powerpc/include/asm/eeh.h
@@ -90,6 +90,8 @@ struct eeh_pe {
 #define EEH_DEV_IRQ_DISABLED    (1 << 3)        /* Interrupt disabled   */
 #define EEH_DEV_DISCONNECTED    (1 << 4)        /* Removing from PE     */
 
+#define EEH_DEV_SYSFS           (1 << 8)        /* Sysfs created        */
+
 struct eeh_dev {
         int mode;                       /* EEH mode                     */
         int class_code;                 /* Class code of the device     */
diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index a5783f1a7a96..ea9414c8088d 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -911,6 +911,7 @@ void eeh_add_device_late(struct pci_dev *dev)
                 eeh_rmv_from_parent_pe(edev);
                 eeh_addr_cache_rmv_dev(edev->pdev);
                 eeh_sysfs_remove_device(edev->pdev);
+                edev->mode &= ~EEH_DEV_SYSFS;
 
                 edev->pdev = NULL;
                 dev->dev.archdata.edev = NULL;
@@ -1016,6 +1017,7 @@ void eeh_remove_device(struct pci_dev *dev)
 
         eeh_addr_cache_rmv_dev(dev);
         eeh_sysfs_remove_device(dev);
+        edev->mode &= ~EEH_DEV_SYSFS;
 }
 
 static int proc_eeh_show(struct seq_file *m, void *v)
diff --git a/arch/powerpc/kernel/eeh_sysfs.c b/arch/powerpc/kernel/eeh_sysfs.c
index 61e2a1452131..5d753d4f2c75 100644
--- a/arch/powerpc/kernel/eeh_sysfs.c
+++ b/arch/powerpc/kernel/eeh_sysfs.c
@@ -56,26 +56,40 @@ EEH_SHOW_ATTR(eeh_pe_config_addr,  pe_config_addr,  "0x%x");
 
 void eeh_sysfs_add_device(struct pci_dev *pdev)
 {
+        struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev);
         int rc=0;
 
+        if (edev && (edev->mode & EEH_DEV_SYSFS))
+                return;
+
         rc += device_create_file(&pdev->dev, &dev_attr_eeh_mode);
         rc += device_create_file(&pdev->dev, &dev_attr_eeh_config_addr);
         rc += device_create_file(&pdev->dev, &dev_attr_eeh_pe_config_addr);
 
         if (rc)
                 printk(KERN_WARNING "EEH: Unable to create sysfs entries\n");
+        else if (edev)
+                edev->mode |= EEH_DEV_SYSFS;
 }
 
 void eeh_sysfs_remove_device(struct pci_dev *pdev)
 {
+        struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev);
+
         /*
          * The parent directory might have been removed. We needn't
          * continue for that case.
          */
-        if (!pdev->dev.kobj.sd)
+        if (!pdev->dev.kobj.sd) {
+                if (edev)
+                        edev->mode &= ~EEH_DEV_SYSFS;
                 return;
+        }
 
         device_remove_file(&pdev->dev, &dev_attr_eeh_mode);
         device_remove_file(&pdev->dev, &dev_attr_eeh_config_addr);
         device_remove_file(&pdev->dev, &dev_attr_eeh_pe_config_addr);
+
+        if (edev)
+                edev->mode &= ~EEH_DEV_SYSFS;
 }
diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c b/arch/powerpc/platforms/powernv/eeh-powernv.c
index 4361a5c7f3ab..79663d26e6ea 100644
--- a/arch/powerpc/platforms/powernv/eeh-powernv.c
+++ b/arch/powerpc/platforms/powernv/eeh-powernv.c
@@ -122,8 +122,8 @@ static int powernv_eeh_dev_probe(struct pci_dev *dev, void *flag)
                 return 0;
 
         /* Initialize eeh device */
-        edev->class_code        = dev->class;
-        edev->mode              = 0;
+        edev->class_code = dev->class;
+        edev->mode      &= 0xFFFFFF00;
         if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
                 edev->mode |= EEH_DEV_BRIDGE;
         if (pci_is_pcie(dev)) {
diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index 9e80f0af311f..7fbc25b1813f 100644
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -218,7 +218,7 @@ static void *pseries_eeh_of_probe(struct device_node *dn, void *flag)
          */
         edev->class_code = *class_code;
         edev->pcie_cap = pseries_eeh_find_cap(dn, PCI_CAP_ID_EXP);
-        edev->mode = 0;
+        edev->mode &= 0xFFFFFF00;
         if ((edev->class_code >> 8) == PCI_CLASS_BRIDGE_PCI) {
                 edev->mode |= EEH_DEV_BRIDGE;
                 if (edev->pcie_cap) {