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[24.6.192.50]) by smtp.gmail.com with ESMTPSA id u79-v6sm18620287pfd.117.2018.10.15.19.39.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 15 Oct 2018 19:39:11 -0700 (PDT) From: frowand.list@gmail.com To: Rob Herring , Pantelis Antoniou , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Alan Tull , Moritz Fischer Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, devicetree@vger.kernel.org, linux-fpga@vger.kernel.org Subject: [PATCH v4 01/18] of: overlay: add tests to validate kfrees from overlay removal Date: Mon, 15 Oct 2018 19:37:21 -0700 Message-Id: <1539657458-24401-2-git-send-email-frowand.list@gmail.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1539657458-24401-1-git-send-email-frowand.list@gmail.com> References: <1539657458-24401-1-git-send-email-frowand.list@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Frank Rowand 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() overlay node /testcase-data/overlay-node/test-bus/test-unittest11/test-unittest111 contains unexpected properties OF: ERROR: memory leak - destroy cset entry: attach overlay node /testcase-data-2/substation@100/hvac-medium-2 expected refcount 1 instead of 2. of_node_get() / of_node_put() are unbalanced for this node. Signed-off-by: Frank Rowand --- Changes since v3: - Add expected value of refcount for destroy cset entry error. Also explain the cause of the error. 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..24c97b7a050f 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 %s() overlay node %pOF before free overlay changeset\n", + __func__, 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() overlay node %pOF contains unexpected properties\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 - destroy cset entry: attach overlay node %pOF expected refcount 1 instead of %d. of_node_get() / of_node_put() are unbalanced for this node.\n", + ce->np, kref_read(&ce->np->kobj.kref)); + } 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 eda57ef12fd0..1176cb4b6e4e 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 4d25e4f952d9..aa1dafaec6ae 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