edac: core fix to use dynamic kobject

Static kobjects are not supported in linux kernel.  Convert the
edac_pci_top_main_kobj from static to dynamic.  This avoids the double
free of the edac_pci_top_main_kobj.name that we see on module reload of
the e752x edac driver (and probably others as well).

In addition Greg KH <greg@kroah.com> has pointed out that this code may be
cleaned up significantly.  I will look at that as a follow-on patch, for
now, I just want the minimum fix to get this double-free oops bug
squashed...

Many thanks to Greg KH for his patience in showing me what the
Documentation/kobject.txt already said (oops)...

Signed-off-by: Arthur Jones <ajones@riverbed.com>
Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 9 deletions

diff --git a/drivers/edac/edac_pci_sysfs.c b/drivers/edac/edac_pci_sysfs.c
index 2c1fa1bb6df2..5c153dccc95e 100644
--- a/drivers/edac/edac_pci_sysfs.c
+++ b/drivers/edac/edac_pci_sysfs.c
@@ -28,7 +28,7 @@ static int edac_pci_poll_msec = 1000;	/* one second workq period */
 static atomic_t pci_parity_count = ATOMIC_INIT(0);
 static atomic_t pci_nonparity_count = ATOMIC_INIT(0);
 
-static struct kobject edac_pci_top_main_kobj;
+static struct kobject *edac_pci_top_main_kobj;
 static atomic_t edac_pci_sysfs_refcount = ATOMIC_INIT(0);
 
 /* getter functions for the data variables */
@@ -83,7 +83,7 @@ static void edac_pci_instance_release(struct kobject *kobj)
         pci = to_instance(kobj);
 
         /* decrement reference count on top main kobj */
-        kobject_put(&edac_pci_top_main_kobj);
+        kobject_put(edac_pci_top_main_kobj);
 
         kfree(pci);     /* Free the control struct */
 }
@@ -166,7 +166,7 @@ static int edac_pci_create_instance_kobj(struct edac_pci_ctl_info *pci, int idx)
          * track the number of PCI instances we have, and thus nest
          * properly on keeping the module loaded
          */
-        main_kobj = kobject_get(&edac_pci_top_main_kobj);
+        main_kobj = kobject_get(edac_pci_top_main_kobj);
         if (!main_kobj) {
                 err = -ENODEV;
                 goto error_out;
@@ -174,11 +174,11 @@ static int edac_pci_create_instance_kobj(struct edac_pci_ctl_info *pci, int idx)
 
         /* And now register this new kobject under the main kobj */
         err = kobject_init_and_add(&pci->kobj, &ktype_pci_instance,
-                                   &edac_pci_top_main_kobj, "pci%d", idx);
+                                   edac_pci_top_main_kobj, "pci%d", idx);
         if (err != 0) {
                 debugf2("%s() failed to register instance pci%d\n",
                         __func__, idx);
-                kobject_put(&edac_pci_top_main_kobj);
+                kobject_put(edac_pci_top_main_kobj);
                 goto error_out;
         }
 
@@ -316,9 +316,10 @@ static struct edac_pci_dev_attribute *edac_pci_attr[] = {
  */
 static void edac_pci_release_main_kobj(struct kobject *kobj)
 {
-
         debugf0("%s() here to module_put(THIS_MODULE)\n", __func__);
 
+        kfree(kobj);
+
         /* last reference to top EDAC PCI kobject has been removed,
          * NOW release our ref count on the core module
          */
@@ -369,8 +370,16 @@ static int edac_pci_main_kobj_setup(void)
                 goto decrement_count_fail;
         }
 
+        edac_pci_top_main_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
+        if (!edac_pci_top_main_kobj) {
+                debugf1("Failed to allocate\n");
+                err = -ENOMEM;
+                goto kzalloc_fail;
+        }
+
         /* Instanstiate the pci object */
-        err = kobject_init_and_add(&edac_pci_top_main_kobj, &ktype_edac_pci_main_kobj,
+        err = kobject_init_and_add(edac_pci_top_main_kobj,
+                                   &ktype_edac_pci_main_kobj,
                                    &edac_class->kset.kobj, "pci");
         if (err) {
                 debugf1("Failed to register '.../edac/pci'\n");
@@ -381,13 +390,16 @@ static int edac_pci_main_kobj_setup(void)
          * for EDAC PCI, then edac_pci_main_kobj_teardown()
          * must be used, for resources to be cleaned up properly
          */
-        kobject_uevent(&edac_pci_top_main_kobj, KOBJ_ADD);
+        kobject_uevent(edac_pci_top_main_kobj, KOBJ_ADD);
         debugf1("Registered '.../edac/pci' kobject\n");
 
         return 0;
 
         /* Error unwind statck */
 kobject_init_and_add_fail:
+        kfree(edac_pci_top_main_kobj);
+
+kzalloc_fail:
         module_put(THIS_MODULE);
 
 decrement_count_fail:
@@ -414,7 +426,7 @@ static void edac_pci_main_kobj_teardown(void)
         if (atomic_dec_return(&edac_pci_sysfs_refcount) == 0) {
                 debugf0("%s() called kobject_put on main kobj\n",
                         __func__);
-                kobject_put(&edac_pci_top_main_kobj);
+                kobject_put(edac_pci_top_main_kobj);
         }
 }