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ftrace: Drop a VLA in module_exists() 

Avoid a VLA 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.

Link: http://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Link: http://lkml.kernel.org/r/1522399988-8815-1-git-send-email-s.mesoraca16@gmail.com

Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Salvatore Mesoraca 2018-03-30 10:53:08 +02:00 committed by Steven Rostedt (VMware)
parent 913ea4d0b1
commit 419e9fe53b
1 changed files with 3 additions and 4 deletions
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7
kernel/trace/ftrace.c
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@ -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);