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[PATCH 2/2] ftrace: Add more checks for FTRACE_FL_DISABLED in processing ip records

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  [PATCH 2/2] ftrace: Add more checks for FTRACE_FL_DISABLED in processing ip  records Steven Rostedt <rostedt@goodmis.org> - 2016-11-15 15:30 +0100

#1522764 — [PATCH 2/2] ftrace: Add more checks for FTRACE_FL_DISABLED in processing ip records

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

When a module is first loaded and its function ip records are added to the
ftrace list of functions to modify, they are set to DISABLED, as their text
is still in a read only state. When the module is fully loaded, and can be
updated, the flag is cleared, and if their's any functions that should be
tracing them, it is updated at that moment.

But there's several locations that do record accounting and should ignore
records that are marked as disabled, or they can cause issues.

Alexei already fixed one location, but others need to be addressed.

Cc: stable@vger.kernel.org
Fixes: b7ffffbb46f2 "ftrace: Add infrastructure for delayed enabling of module functions"
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 326498baab83..da87b3cba5b3 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1862,6 +1862,10 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops,
 
 	/* Update rec->flags */
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		/* We need to update only differences of filter_hash */
 		in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
 		in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
@@ -1884,6 +1888,10 @@ rollback:
 
 	/* Roll back what we did above */
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (rec == end)
 			goto err_out;
 
@@ -2397,6 +2405,10 @@ void __weak ftrace_replace_code(int enable)
 		return;
 
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		failed = __ftrace_replace_code(rec, enable);
 		if (failed) {
 			ftrace_bug(failed, rec);
@@ -3598,6 +3610,10 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
 		goto out_unlock;
 
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
 			ret = enter_record(hash, rec, clear_filter);
 			if (ret < 0) {
@@ -3793,6 +3809,9 @@ register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 
 	do_for_each_ftrace_rec(pg, rec) {
 
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (!ftrace_match_record(rec, &func_g, NULL, 0))
 			continue;
 
@@ -4685,6 +4704,9 @@ ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer)
 
 	do_for_each_ftrace_rec(pg, rec) {
 
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (ftrace_match_record(rec, &func_g, NULL, 0)) {
 			/* if it is in the array */
 			exists = false;
-- 
2.10.2

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