Tracing fix for histograms and a clean up in ftrace

- Fixed a bug that broke the .sym-offset modifier and added a test to make
    sure nothing breaks it again.
 
  - Replace a list_del/list_add() with a list_move()
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Merge tag 'trace-v5.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix and cleanup from Steven Rostedt:
 "Tracing fix for histograms and a clean up in ftrace:

   - Fixed a bug that broke the .sym-offset modifier and added a test to
     make sure nothing breaks it again.

   - Replace a list_del/list_add() with a list_move()"

* tag 'trace-v5.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Use list_move instead of list_del/list_add
  tracing/selftests: Add tests to test histogram sym and sym-offset modifiers
  tracing/histograms: Fix parsing of "sym-offset" modifier

kernel/trace/ftrace.c

@@ -4212,8 +4212,7 @@ static void process_mod_list(struct list_head *head, struct ftrace_ops *ops,
 		if (!func) /* warn? */
 			continue;
 
-		list_del(&ftrace_mod->list);
-		list_add(&ftrace_mod->list, &process_mods);
+		list_move(&ftrace_mod->list, &process_mods);
 
 		/* Use the newly allocated func, as it may be "*" */
 		kfree(ftrace_mod->func);

kernel/trace/trace_events_hist.c

@@ -1555,6 +1555,13 @@ static int contains_operator(char *str)
 
 	switch (*op) {
 	case '-':
+		/*
+		 * Unfortunately, the modifier ".sym-offset"
+		 * can confuse things.
+		 */
+		if (op - str >= 4 && !strncmp(op - 4, ".sym-offset", 11))
+			return FIELD_OP_NONE;
+
 		if (*str == '-')
 			field_op = FIELD_OP_UNARY_MINUS;
 		else

tools/testing/selftests/ftrace/test.d/trigger/trigger-hist.tc

@@ -39,6 +39,24 @@ grep "parent_comm: $COMM" events/sched/sched_process_fork/hist > /dev/null || \
 
 reset_trigger
 
+echo "Test histogram with sym modifier"
+
+echo 'hist:keys=call_site.sym' > events/kmem/kmalloc/trigger
+for i in `seq 1 10` ; do ( echo "forked" > /dev/null); done
+grep '{ call_site: \[[0-9a-f][0-9a-f]*\] [_a-zA-Z][_a-zA-Z]* *}' events/kmem/kmalloc/hist > /dev/null || \
+    fail "sym modifier on kmalloc call_site did not work"
+
+reset_trigger
+
+echo "Test histogram with sym-offset modifier"
+
+echo 'hist:keys=call_site.sym-offset' > events/kmem/kmalloc/trigger
+for i in `seq 1 10` ; do ( echo "forked" > /dev/null); done
+grep '{ call_site: \[[0-9a-f][0-9a-f]*\] [_a-zA-Z][_a-zA-Z]*+0x[0-9a-f][0-9a-f]*' events/kmem/kmalloc/hist > /dev/null || \
+    fail "sym-offset modifier on kmalloc call_site did not work"
+
+reset_trigger
+
 echo "Test histogram with sort key"
 
 echo 'hist:keys=parent_pid,child_pid:sort=child_pid.ascending' > events/sched/sched_process_fork/trigger