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

From: Chris J Arges
Date: Mon Nov 02 2015 - 12:59:40 EST


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@xxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxxxx
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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