[PATCH 3/3] Add marker_query service

Introduce marker_query(name, instance) to obtain a reference to a
marker's __mark_marker_data structure. This information can be used to
search for markers of a specific name and check the returned format
string for consistency in more flexible ways or defer the check. So far
consistency checks are done via a full string match on marker_set_probe
invocation, now we can also apply checksum tests without having to know
the string in advance in the context of marker_set_probe.


Signed-off-by: Jan Kiszka <[email protected]>

---
 include/linux/marker.h |    1 +
 kernel/module.c        |   47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

Index: linux-2.6.21.1/kernel/module.c
===================================================================
--- linux-2.6.21.1.orig/kernel/module.c
+++ linux-2.6.21.1/kernel/module.c
@@ -448,6 +448,26 @@ static int marker_list_probe_range(marke
 	return found;
 }
 
+/* Looks up a marker by its name and instance number within the specificed
+ * range and returns the associated data structure. */
+const struct __mark_marker_data *marker_query_range(const char *name,
+	int instance,
+	const struct __mark_marker *begin,
+	const struct __mark_marker *end)
+{
+	const struct __mark_marker *iter;
+	int found = 0;
+
+	for (iter = begin; iter < end; iter++) {
+		if (strcmp(name, iter->mdata->name) != 0)
+			continue;
+
+		if (found++ == instance)
+			return iter->mdata;
+	}
+	return NULL;
+}
+
 /* Calls _marker_set_probe_range for the core markers and modules markers.
  * Marker enabling/disabling use the modlist_lock to synchronise. */
 int _marker_set_probe(int flags, const char *name, const char *format,
@@ -522,6 +542,33 @@ int marker_list_probe(marker_probe_func 
 	return found;
 }
 EXPORT_SYMBOL_GPL(marker_list_probe);
+
+/* Looks up a marker by its name and instance number and returns the
+ * associated data structure. */
+const struct __mark_marker_data *marker_query(const char *name, int instance)
+{
+	struct module *mod;
+	const struct __mark_marker_data *mdata;
+
+	mutex_lock(&module_mutex);
+	/* Core kernel markers */
+	mdata = marker_query_range(name, instance,
+			__start___markers, __stop___markers);
+	if (!mdata) {
+		/* Markers in modules. */
+		list_for_each_entry(mod, &modules, list)
+			if (!mod->taints) {
+				mdata = marker_query_range(name, instance,
+					mod->markers,
+					mod->markers+mod->num_markers);
+				if (mdata)
+					break;
+			}
+	}
+	mutex_unlock(&module_mutex);
+	return mdata;
+}
+EXPORT_SYMBOL_GPL(marker_query);
 #endif
 
 #ifdef CONFIG_SMP
Index: linux-2.6.21.1/include/linux/marker.h
===================================================================
--- linux-2.6.21.1.orig/include/linux/marker.h
+++ linux-2.6.21.1/include/linux/marker.h
@@ -116,6 +116,7 @@ extern int _marker_set_probe(int flags, 
 
 extern int marker_remove_probe(const char *name);
 extern int marker_list_probe(marker_probe_func *probe);
+const struct __mark_marker_data *marker_query(const char *name, int instance);
 
 #endif /* __KERNEL__ */
 #endif

_______________________________________________
Ltt-dev mailing list
[email protected]
http://listserv.shafik.org/mailman/listinfo/ltt-dev

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.5 (GNU/Linux)
Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org

iD8DBQFGRO8YniDOoMHTA+kRAtE6AJ9P24xv2AZqogXGBf3549iLIgkGAgCeImGh
vK9Q/VvVa4YGw2c2yJRCOXw=
=0jtT
-----END PGP SIGNATURE-----