Merge tag 'probes-fixes-v6.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes fixes from Masami Hiramatsu:

 - fprobe: Fix RCU warning message in list traversal

   fprobe_module_callback() using hlist_for_each_entry_rcu() traverse
   the fprobe list but it locks fprobe_mutex() instead of rcu lock
   because it is enough. So add lockdep_is_held() to avoid warning.

 - tracing: eprobe: Add missing trace_probe_log_clear for eprobe

   __trace_eprobe_create() uses trace_probe_log but forgot to clear it
   at exit. Add trace_probe_log_clear() calls.

 - tracing: probes: Fix possible race in trace_probe_log APIs

   trace_probe_log APIs are used in probe event (dynamic_events,
   kprobe_events and uprobe_events) creation. Only dynamic_events uses
   the dyn_event_ops_mutex mutex to serialize it. This makes kprobe and
   uprobe events to lock the same mutex to serialize its creation to
   avoid race in trace_probe_log APIs.

* tag 'probes-fixes-v6.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: probes: Fix a possible race in trace_probe_log APIs
  tracing: add missing trace_probe_log_clear for eprobes
  tracing: fprobe: Fix RCU warning message in list traversal

Author: torvalds

kernel/trace/fprobe.c

@@ -454,7 +454,8 @@ static void fprobe_remove_node_in_module(struct module *mod, struct hlist_head *
 	struct fprobe_hlist_node *node;
 	int ret = 0;
 
-	hlist_for_each_entry_rcu(node, head, hlist) {
+	hlist_for_each_entry_rcu(node, head, hlist,
+				 lockdep_is_held(&fprobe_mutex)) {
 		if (!within_module(node->addr, mod))
 			continue;
 		if (delete_fprobe_node(node))

kernel/trace/trace_dynevent.c

@@ -16,7 +16,7 @@
 #include "trace_output.h"	/* for trace_event_sem */
 #include "trace_dynevent.h"
 
-static DEFINE_MUTEX(dyn_event_ops_mutex);
+DEFINE_MUTEX(dyn_event_ops_mutex);
 static LIST_HEAD(dyn_event_ops_list);
 
 bool trace_event_dyn_try_get_ref(struct trace_event_call *dyn_call)
@@ -116,6 +116,20 @@ int dyn_event_release(const char *raw_command, struct dyn_event_operations *type
 	return ret;
 }
 
+/*
+ * Locked version of event creation. The event creation must be protected by
+ * dyn_event_ops_mutex because of protecting trace_probe_log.
+ */
+int dyn_event_create(const char *raw_command, struct dyn_event_operations *type)
+{
+	int ret;
+
+	mutex_lock(&dyn_event_ops_mutex);
+	ret = type->create(raw_command);
+	mutex_unlock(&dyn_event_ops_mutex);
+	return ret;
+}
+
 static int create_dyn_event(const char *raw_command)
 {
 	struct dyn_event_operations *ops;

kernel/trace/trace_dynevent.h

@@ -100,6 +100,7 @@ void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
 void dyn_event_seq_stop(struct seq_file *m, void *v);
 int dyn_events_release_all(struct dyn_event_operations *type);
 int dyn_event_release(const char *raw_command, struct dyn_event_operations *type);
+int dyn_event_create(const char *raw_command, struct dyn_event_operations *type);
 
 /*
  * for_each_dyn_event	-	iterate over the dyn_event list

kernel/trace/trace_eprobe.c

@@ -969,10 +969,13 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 			goto error;
 		}
 	}
+	trace_probe_log_clear();
 	return ret;
+
 parse_error:
 	ret = -EINVAL;
 error:
+	trace_probe_log_clear();
 	trace_event_probe_cleanup(ep);
 	return ret;
 }

kernel/trace/trace_kprobe.c

@@ -1089,7 +1089,7 @@ static int create_or_delete_trace_kprobe(const char *raw_command)
 	if (raw_command[0] == '-')
 		return dyn_event_release(raw_command, &trace_kprobe_ops);
 
-	ret = trace_kprobe_create(raw_command);
+	ret = dyn_event_create(raw_command, &trace_kprobe_ops);
 	return ret == -ECANCELED ? -EINVAL : ret;
 }
 

kernel/trace/trace_probe.c

@@ -154,9 +154,12 @@ static const struct fetch_type *find_fetch_type(const char *type, unsigned long
 }
 
 static struct trace_probe_log trace_probe_log;
+extern struct mutex dyn_event_ops_mutex;
 
 void trace_probe_log_init(const char *subsystem, int argc, const char **argv)
 {
+	lockdep_assert_held(&dyn_event_ops_mutex);
+
 	trace_probe_log.subsystem = subsystem;
 	trace_probe_log.argc = argc;
 	trace_probe_log.argv = argv;
@@ -165,11 +168,15 @@ void trace_probe_log_init(const char *subsystem, int argc, const char **argv)
 
 void trace_probe_log_clear(void)
 {
+	lockdep_assert_held(&dyn_event_ops_mutex);
+
 	memset(&trace_probe_log, 0, sizeof(trace_probe_log));
 }
 
 void trace_probe_log_set_index(int index)
 {
+	lockdep_assert_held(&dyn_event_ops_mutex);
+
 	trace_probe_log.index = index;
 }
 
@@ -178,6 +185,8 @@ void __trace_probe_log_err(int offset, int err_type)
 	char *command, *p;
 	int i, len = 0, pos = 0;
 
+	lockdep_assert_held(&dyn_event_ops_mutex);
+
 	if (!trace_probe_log.argv)
 		return;
 

kernel/trace/trace_uprobe.c

@@ -741,7 +741,7 @@ static int create_or_delete_trace_uprobe(const char *raw_command)
 	if (raw_command[0] == '-')
 		return dyn_event_release(raw_command, &trace_uprobe_ops);
 
-	ret = trace_uprobe_create(raw_command);
+	ret = dyn_event_create(raw_command, &trace_uprobe_ops);
 	return ret == -ECANCELED ? -EINVAL : ret;
 }