linux-kernel - [PATCH 4.8 07/67] ftrace: Add more checks for FTRACE_FL

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Date:   Thu, 24 Nov 2016 16:27:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH 4.8 07/67] ftrace: Add more checks for FTRACE_FL_DISABLED in processing ip records

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit 546fece4eae871f033925ccf0ff2b740725ae915 upstream.

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.

Fixes: b7ffffbb46f2 "ftrace: Add infrastructure for delayed enabling of module functions"
Reported-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/trace/ftrace.c |   22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1856,6 +1856,10 @@ static int __ftrace_hash_update_ipmodify
 
 	/* 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);
@@ -1878,6 +1882,10 @@ 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;
 
@@ -2391,6 +2399,10 @@ void __weak ftrace_replace_code(int enab
 		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);
@@ -3592,6 +3604,10 @@ match_records(struct ftrace_hash *hash,
 		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) {
@@ -3787,6 +3803,9 @@ register_ftrace_function_probe(char *glo
 
 	do_for_each_ftrace_rec(pg, rec) {
 
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (!ftrace_match_record(rec, &func_g, NULL, 0))
 			continue;
 
@@ -4679,6 +4698,9 @@ ftrace_set_func(unsigned long *array, in
 
 	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;