linux-kernel - [PATCH] livepatch: old_name.number scheme in livepatch sysfs directory

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Date:	Mon,  2 Nov 2015 11:58:47 -0600
From:	Chris J Arges <chris.j.arges@...onical.com>
To:	live-patching@...r.kernel.org
Cc:	jeyu@...hat.com, Chris J Arges <chris.j.arges@...onical.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Seth Jennings <sjenning@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Vojtech Pavlik <vojtech@...e.com>, linux-api@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] livepatch: old_name.number scheme in livepatch sysfs directory

The following directory structure will allow for cases when the same
function name exists in a single object.
	/sys/kernel/livepatch/<patch>/<object>/<function.number>

The number is incremented on each known initialized func kobj thus creating
unique names in this case.

An example of this issue is documented here:
	https://github.com/dynup/kpatch/issues/493

Signed-off-by: Chris J Arges <chris.j.arges@...onical.com>
---
 Documentation/ABI/testing/sysfs-kernel-livepatch |  2 +-
 kernel/livepatch/core.c                          | 20 ++++++++++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
index 5bf42a8..dcd36db 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -33,7 +33,7 @@ Description:
 		The object directory contains subdirectories for each function
 		that is patched within the object.
 
-What:		/sys/kernel/livepatch/<patch>/<object>/<function>
+What:		/sys/kernel/livepatch/<patch>/<object>/<function.number>
 Date:		Nov 2014
 KernelVersion:	3.19.0
 Contact:	live-patching@...r.kernel.org
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 6e53441..ecacf65 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -587,7 +587,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch);
  * /sys/kernel/livepatch/<patch>
  * /sys/kernel/livepatch/<patch>/enabled
  * /sys/kernel/livepatch/<patch>/<object>
- * /sys/kernel/livepatch/<patch>/<object>/<func>
+ * /sys/kernel/livepatch/<patch>/<object>/<func.number>
  */
 
 static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
@@ -727,13 +727,29 @@ static void klp_free_patch(struct klp_patch *patch)
 	kobject_put(&patch->kobj);
 }
 
+static int klp_count_sysfs_funcs(struct klp_object *obj, const char *name)
+{
+	struct klp_func *func;
+	int n = 0;
+
+	/* count the times a function name occurs and is initialized */
+	klp_for_each_func(obj, func) {
+		if ((!strcmp(func->old_name, name) &&
+		    func->kobj.state_initialized))
+			n++;
+	}
+
+	return n;
+}
+
 static int klp_init_func(struct klp_object *obj, struct klp_func *func)
 {
 	INIT_LIST_HEAD(&func->stack_node);
 	func->state = KLP_DISABLED;
 
 	return kobject_init_and_add(&func->kobj, &klp_ktype_func,
-				    &obj->kobj, "%s", func->old_name);
+				    &obj->kobj, "%s.%d", func->old_name,
+				    klp_count_sysfs_funcs(obj, func->old_name));
 }
 
 /* parts of the initialization that is done only when the object is loaded */
-- 
1.9.1

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