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>

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	*/

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)

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;
 }

arch/powerpc/platforms/powernv/eeh-powernv.c

@@ -123,7 +123,7 @@ static int powernv_eeh_dev_probe(struct pci_dev *dev, void *flag)
 
 	/* Initialize eeh device */
 	edev->class_code = dev->class;
-	edev->mode		= 0;
+	edev->mode	&= 0xFFFFFF00;
 	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
 		edev->mode |= EEH_DEV_BRIDGE;
 	if (pci_is_pcie(dev)) {

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) {