linux-kernel - [PATCH v2] tracing: Deal with error return code of the ftrace_process

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Date:   Thu, 20 Jan 2022 06:59:49 +0000
From:   Yuntao Wang <ytcoode@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Yuntao Wang <ytcoode@...il.com>
Subject: [PATCH v2] tracing: Deal with error return code of the ftrace_process_locs() function

The ftrace_process_locs() function may return -ENOMEM error code, which
should be handled by the callers.

Signed-off-by: Yuntao Wang <ytcoode@...il.com>
---
Changes since v1:
- Deal with error return code instead of just removing it

 kernel/trace/ftrace.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6163b6f762f7..eb98797b399b 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6791,11 +6791,16 @@ void ftrace_module_enable(struct module *mod)
 
 void ftrace_module_init(struct module *mod)
 {
+	int ret;
+
 	if (ftrace_disabled || !mod->num_ftrace_callsites)
 		return;
 
-	ftrace_process_locs(mod, mod->ftrace_callsites,
-			    mod->ftrace_callsites + mod->num_ftrace_callsites);
+	ret = ftrace_process_locs(mod, mod->ftrace_callsites,
+				  mod->ftrace_callsites + mod->num_ftrace_callsites);
+	if (ret)
+		pr_warn("ftrace: failed to allocate entries for module '%s' functions\n",
+			mod->name);
 }
 
 static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
@@ -7126,15 +7131,19 @@ void __init ftrace_init(void)
 	pr_info("ftrace: allocating %ld entries in %ld pages\n",
 		count, count / ENTRIES_PER_PAGE + 1);
 
-	last_ftrace_enabled = ftrace_enabled = 1;
-
 	ret = ftrace_process_locs(NULL,
 				  __start_mcount_loc,
 				  __stop_mcount_loc);
+	if (ret) {
+		pr_warn("ftrace: failed to allocate entries for functions\n");
+		goto failed;
+	}
 
 	pr_info("ftrace: allocated %ld pages with %ld groups\n",
 		ftrace_number_of_pages, ftrace_number_of_groups);
 
+	last_ftrace_enabled = ftrace_enabled = 1;
+
 	set_ftrace_early_filters();
 
 	return;
-- 
2.34.1.75.gabe6bb3905