Patch "powerpc/powernv : Drop reference added by kset_find_obj()" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    powerpc/powernv : Drop reference added by kset_find_obj()

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-powernv-drop-reference-added-by-kset_find_obj.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From a9cbf0b2195b695cbeeeecaa4e2770948c212e9a Mon Sep 17 00:00:00 2001
From: Mukesh Ojha <mukesh02@linux.vnet.ibm.com>
Date: Mon, 22 Aug 2016 12:17:44 +0530
Subject: powerpc/powernv : Drop reference added by kset_find_obj()

From: Mukesh Ojha <mukesh02@linux.vnet.ibm.com>

commit a9cbf0b2195b695cbeeeecaa4e2770948c212e9a upstream.

In a situation, where Linux kernel gets notified about duplicate error log
from OPAL, it is been observed that kernel fails to remove sysfs entries
(/sys/firmware/opal/elog/0xXXXXXXXX) of such error logs. This is because,
we currently search the error log/dump kobject in the kset list via
'kset_find_obj()' routine. Which eventually increment the reference count
by one, once it founds the kobject.

So, unless we decrement the reference count by one after it found the kobject,
we would not be able to release the kobject properly later.

This patch adds the 'kobject_put()' which was missing earlier.

Signed-off-by: Mukesh Ojha <mukesh02@linux.vnet.ibm.com>
Reviewed-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/powerpc/platforms/powernv/opal-dump.c |    7 ++++++-
 arch/powerpc/platforms/powernv/opal-elog.c |    7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

--- a/arch/powerpc/platforms/powernv/opal-dump.c
+++ b/arch/powerpc/platforms/powernv/opal-dump.c
@@ -370,6 +370,7 @@ static irqreturn_t process_dump(int irq,
 	uint32_t dump_id, dump_size, dump_type;
 	struct dump_obj *dump;
 	char name[22];
+	struct kobject *kobj;
 
 	rc = dump_read_info(&dump_id, &dump_size, &dump_type);
 	if (rc != OPAL_SUCCESS)
@@ -381,8 +382,12 @@ static irqreturn_t process_dump(int irq,
 	 * that gracefully and not create two conflicting
 	 * entries.
 	 */
-	if (kset_find_obj(dump_kset, name))
+	kobj = kset_find_obj(dump_kset, name);
+	if (kobj) {
+		/* Drop reference added by kset_find_obj() */
+		kobject_put(kobj);
 		return 0;
+	}
 
 	dump = create_dump_obj(dump_id, dump_size, dump_type);
 	if (!dump)
--- a/arch/powerpc/platforms/powernv/opal-elog.c
+++ b/arch/powerpc/platforms/powernv/opal-elog.c
@@ -247,6 +247,7 @@ static irqreturn_t elog_event(int irq, v
 	uint64_t elog_type;
 	int rc;
 	char name[2+16+1];
+	struct kobject *kobj;
 
 	rc = opal_get_elog_size(&id, &size, &type);
 	if (rc != OPAL_SUCCESS) {
@@ -269,8 +270,12 @@ static irqreturn_t elog_event(int irq, v
 	 * that gracefully and not create two conflicting
 	 * entries.
 	 */
-	if (kset_find_obj(elog_kset, name))
+	kobj = kset_find_obj(elog_kset, name);
+	if (kobj) {
+		/* Drop reference added by kset_find_obj() */
+		kobject_put(kobj);
 		return IRQ_HANDLED;
+	}
 
 	create_elog_obj(log_id, elog_size, elog_type);
 


Patches currently in stable-queue which might be from mukesh02@linux.vnet.ibm.com are

queue-4.4/powerpc-powernv-drop-reference-added-by-kset_find_obj.patch