From 35c35493b0e3343522256f6054516f4e2161a6d4 Mon Sep 17 00:00:00 2001 From: Chuhong Yuan Date: Fri, 9 Aug 2019 15:10:34 +0800 Subject: [PATCH] printk: Replace strncmp() with str_has_prefix() strncmp(str, const, len) is error-prone because len is easy to have typo. An example is the hard-coded len has counting error or sizeof(const) forgets - 1. So we prefer using newly introduced str_has_prefix() to substitute such strncmp() to make code better. Link: http://lkml.kernel.org/r/20190809071034.17279-1-hslester96@gmail.com Cc: "Steven Rostedt" Cc: linux-kernel@vger.kernel.org Signed-off-by: Chuhong Yuan Reviewed-by: Sergey Senozhatsky [pmladek@suse.com: Slightly updated and reformatted the commit message.] Signed-off-by: Petr Mladek --- kernel/printk/braille.c | 15 +++++++++++---- kernel/printk/printk.c | 26 ++++++++++++++++++-------- 2 files changed, 29 insertions(+), 12 deletions(-) diff --git a/kernel/printk/braille.c b/kernel/printk/braille.c index 1d21ebacfdb8..17a9591e54ff 100644 --- a/kernel/printk/braille.c +++ b/kernel/printk/braille.c @@ -11,11 +11,18 @@ int _braille_console_setup(char **str, char **brl_options) { - if (!strncmp(*str, "brl,", 4)) { + size_t len; + + len = str_has_prefix(*str, "brl,"); + if (len) { *brl_options = ""; - *str += 4; - } else if (!strncmp(*str, "brl=", 4)) { - *brl_options = *str + 4; + *str += len; + return 0; + } + + len = str_has_prefix(*str, "brl="); + if (len) { + *brl_options = *str + len; *str = strchr(*brl_options, ','); if (!*str) { pr_err("need port name after brl=\n"); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 1888f6a3b694..43a31015ec93 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -118,19 +118,29 @@ static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; static int __control_devkmsg(char *str) { + size_t len; + if (!str) return -EINVAL; - if (!strncmp(str, "on", 2)) { + len = str_has_prefix(str, "on"); + if (len) { devkmsg_log = DEVKMSG_LOG_MASK_ON; - return 2; - } else if (!strncmp(str, "off", 3)) { - devkmsg_log = DEVKMSG_LOG_MASK_OFF; - return 3; - } else if (!strncmp(str, "ratelimit", 9)) { - devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; - return 9; + return len; } + + len = str_has_prefix(str, "off"); + if (len) { + devkmsg_log = DEVKMSG_LOG_MASK_OFF; + return len; + } + + len = str_has_prefix(str, "ratelimit"); + if (len) { + devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; + return len; + } + return -EINVAL; }