lkml.org 
[lkml]   [2018]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[v2] ftrace: drop a VLA in module_exists()
Date
Avoid a VLA[1] by using a real constant expression instead of a variable.
The compiler should be able to optimize the original code and avoid using
an actual VLA. Anyway this change is useful because it will avoid a false
positive with -Wvla, it might also help the compiler generating better
code.

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
---
kernel/trace/ftrace.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index eac9ce2..16bbf06 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3902,14 +3902,13 @@ static bool module_exists(const char *module)
{
/* All modules have the symbol __this_module */
const char this_mod[] = "__this_module";
- const int modname_size = MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 1;
- char modname[modname_size + 1];
+ char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 2];
unsigned long val;
int n;

- n = snprintf(modname, modname_size + 1, "%s:%s", module, this_mod);
+ n = snprintf(modname, sizeof(modname), "%s:%s", module, this_mod);

- if (n > modname_size)
+ if (n > sizeof(modname) - 1)
return false;

val = module_kallsyms_lookup_name(modname);
--
1.9.1
\
 
 \ /
  Last update: 2018-03-30 10:53    [W:0.064 / U:0.104 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site