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From: frowand.list@gmail.com
To: Rob Herring <robh+dt@kernel.org>,
	Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>, Alan Tull <atull@kernel.org>,
	Moritz Fischer <mdf@kernel.org>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	devicetree@vger.kernel.org, linux-fpga@vger.kernel.org
Subject: [PATCH v7 01/17] of: overlay: add tests to validate kfrees from overlay removal
Date: Thu,  8 Nov 2018 22:05:49 -0800	[thread overview]
Message-ID: <1541743565-23163-2-git-send-email-frowand.list@gmail.com> (raw)
In-Reply-To: <1541743565-23163-1-git-send-email-frowand.list@gmail.com>

From: Frank Rowand <frank.rowand@sony.com>

Add checks:
  - attempted kfree due to refcount reaching zero before overlay
    is removed
  - properties linked to an overlay node when the node is removed
  - node refcount > one during node removal in a changeset destroy,
    if the node was created by the changeset

After applying this patch, several validation warnings will be
reported from the devicetree unittest during boot due to
pre-existing devicetree bugs. The warnings will be similar to:

  OF: ERROR: of_node_release(), unexpected properties in /testcase-data/overlay-node/test-bus/test-unittest11
  OF: ERROR: memory leak, expected refcount 1 instead of 2, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node /testcase-data-2/substation@100/
  hvac-medium-2

Tested-by: Alan Tull <atull@kernel.org>
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
---
 drivers/of/dynamic.c | 29 +++++++++++++++++++++++++++++
 drivers/of/overlay.c |  1 +
 include/linux/of.h   | 15 ++++++++++-----
 3 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index f4f8ed9b5454..12c3f9a15e94 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -330,6 +330,25 @@ void of_node_release(struct kobject *kobj)
 	if (!of_node_check_flag(node, OF_DYNAMIC))
 		return;
 
+	if (of_node_check_flag(node, OF_OVERLAY)) {
+
+		if (!of_node_check_flag(node, OF_OVERLAY_FREE_CSET)) {
+			/* premature refcount of zero, do not free memory */
+			pr_err("ERROR: memory leak before free overlay changeset,  %pOF\n",
+			       node);
+			return;
+		}
+
+		/*
+		 * If node->properties non-empty then properties were added
+		 * to this node either by different overlay that has not
+		 * yet been removed, or by a non-overlay mechanism.
+		 */
+		if (node->properties)
+			pr_err("ERROR: %s(), unexpected properties in %pOF\n",
+			       __func__, node);
+	}
+
 	property_list_free(node->properties);
 	property_list_free(node->deadprops);
 
@@ -434,6 +453,16 @@ struct device_node *__of_node_dup(const struct device_node *np,
 
 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
 {
+	if (ce->action == OF_RECONFIG_ATTACH_NODE &&
+	    of_node_check_flag(ce->np, OF_OVERLAY)) {
+		if (kref_read(&ce->np->kobj.kref) > 1) {
+			pr_err("ERROR: memory leak, expected refcount 1 instead of %d, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node %pOF\n",
+			       kref_read(&ce->np->kobj.kref), ce->np);
+		} else {
+			of_node_set_flag(ce->np, OF_OVERLAY_FREE_CSET);
+		}
+	}
+
 	of_node_put(ce->np);
 	list_del(&ce->node);
 	kfree(ce);
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 42b1f73ac5f6..f5fc8859a7ee 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -373,6 +373,7 @@ static int add_changeset_node(struct overlay_changeset *ovcs,
 			return -ENOMEM;
 
 		tchild->parent = target_node;
+		of_node_set_flag(tchild, OF_OVERLAY);
 
 		ret = of_changeset_attach_node(&ovcs->cset, tchild);
 		if (ret)
diff --git a/include/linux/of.h b/include/linux/of.h
index a5aee3c438ad..664cd5573ae2 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -138,11 +138,16 @@ static inline void of_node_put(struct device_node *node) { }
 extern struct device_node *of_stdout;
 extern raw_spinlock_t devtree_lock;
 
-/* flag descriptions (need to be visible even when !CONFIG_OF) */
-#define OF_DYNAMIC	1 /* node and properties were allocated via kmalloc */
-#define OF_DETACHED	2 /* node has been detached from the device tree */
-#define OF_POPULATED	3 /* device already created for the node */
-#define OF_POPULATED_BUS	4 /* of_platform_populate recursed to children of this node */
+/*
+ * struct device_node flag descriptions
+ * (need to be visible even when !CONFIG_OF)
+ */
+#define OF_DYNAMIC		1 /* (and properties) allocated via kmalloc */
+#define OF_DETACHED		2 /* detached from the device tree */
+#define OF_POPULATED		3 /* device already created */
+#define OF_POPULATED_BUS	4 /* platform bus created for children */
+#define OF_OVERLAY		5 /* allocated for an overlay */
+#define OF_OVERLAY_FREE_CSET	6 /* in overlay cset being freed */
 
 #define OF_BAD_ADDR	((u64)-1)
 
-- 
Frank Rowand <frank.rowand@sony.com>


  reply	other threads:[~2018-11-09  6:07 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-09  6:05 [PATCH v7 00/17] of: overlay: validation checks, subsequent fixes frowand.list
2018-11-09  6:05 ` frowand.list [this message]
2018-11-09  6:05 ` [PATCH v7 02/17] of: overlay: add missing of_node_put() after add new node to changeset frowand.list
2018-11-09  6:05 ` [PATCH v7 03/17] of: overlay: add missing of_node_get() in __of_attach_node_sysfs frowand.list
2018-11-09  6:05 ` [PATCH v7 04/17] powerpc/pseries: add of_node_put() in dlpar_detach_node() frowand.list
2018-11-09  6:05 ` [PATCH v7 05/17] of: overlay: use prop add changeset entry for property in new nodes frowand.list
2018-11-09  6:05 ` [PATCH v7 06/17] of: overlay: do not duplicate properties from overlay for " frowand.list
2018-11-09  6:05 ` [PATCH v7 07/17] of: overlay: reorder fields in struct fragment frowand.list
2018-11-09  6:05 ` [PATCH v7 08/17] of: overlay: validate overlay properties #address-cells and #size-cells frowand.list
2018-11-09  6:05 ` [PATCH v7 09/17] of: overlay: make all pr_debug() and pr_err() messages unique frowand.list
2018-11-09  6:05 ` [PATCH v7 10/17] of: overlay: test case of two fragments adding same node frowand.list
2018-11-09  6:05 ` [PATCH v7 11/17] of: overlay: check prevents multiple fragments add or delete " frowand.list
2018-11-09  6:06 ` [PATCH v7 12/17] of: overlay: check prevents multiple fragments touching same property frowand.list
2018-11-09  6:06 ` [PATCH v7 13/17] of: unittest: remove unused of_unittest_apply_overlay() argument frowand.list
2018-11-09  6:06 ` [PATCH v7 14/17] of: overlay: set node fields from properties when add new overlay node frowand.list
2018-11-09  6:06 ` [PATCH v7 15/17] of: unittest: allow base devicetree to have symbol metadata frowand.list
2018-11-09  6:06 ` [PATCH v7 16/17] of: unittest: find overlays[] entry by name instead of index frowand.list
2018-11-09  6:06 ` [PATCH v7 17/17] of: unittest: initialize args before calling of_*parse_*() frowand.list

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