From 2ce5eace42b859cabef898877b38a0429f931370 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Tue, 10 Mar 2020 19:43:34 +0200 Subject: [PATCH] serial: core: Use string length for SysRq magic sequence MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Compiler is not happy about using ARRAY_SIZE() in comparison to smaller type: CC drivers/tty/serial/serial_core.o .../serial_core.c: In function ‘uart_try_toggle_sysrq’: .../serial_core.c:3222:24: warning: comparison is always false due to limited range of data type [-Wtype-limits] 3222 | if (++port->sysrq_seq < (ARRAY_SIZE(sysrq_toggle_seq) - 1)) { | ^ Looking at the code it appears that there is an additional weirdness, i.e. use ARRAY_SIZE() against simple string literal. Yes, the idea probably was to allow '\0' in the sequence, but it's impractical: kernel configuration won't accept it to begin with followed by a comment about '\0' before comparison in question. Drop all these by switching to strlen() and convert code accordingly. Note, GCC seems clever enough to calculate string length at compile time. Fixes: 68af43173d3f ("serial/sysrq: Add MAGIC_SYSRQ_SERIAL_SEQUENCE") Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com> Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200310174337.74109-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 863e3e0c2d39..f5c8cf847532 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -3110,7 +3110,9 @@ static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on); */ static bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch) { - if (ARRAY_SIZE(sysrq_toggle_seq) <= 1) + int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq); + + if (!sysrq_toggle_seq_len) return false; BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX); @@ -3119,8 +3121,7 @@ static bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch) return false; } - /* Without the last \0 */ - if (++port->sysrq_seq < (ARRAY_SIZE(sysrq_toggle_seq) - 1)) { + if (++port->sysrq_seq < sysrq_toggle_seq_len) { port->sysrq = jiffies + SYSRQ_TIMEOUT; return true; } -- 2.30.2