[PATCH] (1/3) Fix unbalanced dev_get/put calls in PPC64 EEH code

[Paul Mackerras]

From: Linas Vepstas <linas@xxxxxxxxxxxxxx>

This patch fixes some unbalanced usage of pci_dev_get()/pci_dev_put() calls
in the eeh code.  The old code had too many calls to dev_put, which could
cause memory structs to be freed prematurely, possibly leading to bad
bad pointer derefs in certain cases.

Signed-off-by: Linas Vepstas <linas@xxxxxxxxx>
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>

diff -urN linux-2.5/arch/ppc64/kernel/eeh.c test25/arch/ppc64/kernel/eeh.c
--- linux-2.5/arch/ppc64/kernel/eeh.c	2004-07-06 08:43:03.000000000 +1000
+++ test25/arch/ppc64/kernel/eeh.c	2004-07-08 16:56:46.244591376 +1000
@@ -214,7 +214,6 @@
 	if (!dn) {
 		printk(KERN_WARNING "PCI: no pci dn found for dev=%s %s\n",
 			pci_name(dev), pci_pretty_name(dev));
-		pci_dev_put(dev);
 		return;
 	}
 
@@ -225,10 +224,12 @@
 		printk(KERN_INFO "PCI: skip building address cache for=%s %s\n",
 		       pci_name(dev), pci_pretty_name(dev));
 #endif
-		pci_dev_put(dev);
 		return;
 	}
 
+	/* The cache holds a reference to the device... */
+	pci_dev_get(dev);
+
 	/* Walk resources on this device, poke them into the tree */
 	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
 		unsigned long start = pci_resource_start(dev,i);
@@ -278,6 +279,8 @@
 		}
 		n = rb_next(n);
 	}
+
+	/* The cache no longer holds its reference to this device... */
 	pci_dev_put(dev);
 }
 
@@ -317,7 +320,6 @@
 	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
 		/* Ignore PCI bridges ( XXX why ??) */
 		if ((dev->class >> 16) == PCI_BASE_CLASS_BRIDGE) {
-			pci_dev_put(dev);
 			continue;
 		}
 		pci_addr_cache_insert_device(dev);
-
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