2023-02-11 15:47:11

by Tom Rix

Subject: [PATCH] serial: imx: remove a redundant check

cpp_check reports
drivers/tty/serial/imx.c:1207:15: style: Condition 'r_bytes>0' is always true [knownConditionTrueFalse]
if (r_bytes > 0) {

r_byte is set to
r_bytes = rx_ring->head - rx_ring->tail;

The head - tail calculation is also done by the earlier check
if (rx_ring->head <= sg_dma_len(sgl) &&
rx_ring->head > rx_ring->tail) {

so r_bytes will always be > 0, so the second check is not needed.

Signed-off-by: Tom Rix <[email protected]>
---
drivers/tty/serial/imx.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 363c77a140f0..523f296d5747 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1204,11 +1204,9 @@ static void imx_uart_dma_rx_callback(void *data)
r_bytes = rx_ring->head - rx_ring->tail;

/* If we received something, check for 0xff flood */
- if (r_bytes > 0) {
- spin_lock(&sport->port.lock);
- imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
- spin_unlock(&sport->port.lock);
- }
+ spin_lock(&sport->port.lock);
+ imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
+ spin_unlock(&sport->port.lock);

if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) {

--
2.26.3

2023-02-11 17:48:08

by Sergey Organov

Subject: Re: [PATCH] serial: imx: remove a redundant check

Tom Rix <[email protected]> writes:

> cpp_check reports
> drivers/tty/serial/imx.c:1207:15: style: Condition 'r_bytes>0' is always true [knownConditionTrueFalse]
> if (r_bytes > 0) {
>
> r_byte is set to
> r_bytes = rx_ring->head - rx_ring->tail;
>
> The head - tail calculation is also done by the earlier check
> if (rx_ring->head <= sg_dma_len(sgl) &&
> rx_ring->head > rx_ring->tail) {
>
> so r_bytes will always be > 0, so the second check is not needed.
>
> Signed-off-by: Tom Rix <[email protected]>
> ---
> drivers/tty/serial/imx.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 363c77a140f0..523f296d5747 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -1204,11 +1204,9 @@ static void imx_uart_dma_rx_callback(void *data)
> r_bytes = rx_ring->head - rx_ring->tail;
>
> /* If we received something, check for 0xff flood */
> - if (r_bytes > 0) {
> - spin_lock(&sport->port.lock);
> - imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
> - spin_unlock(&sport->port.lock);
> - }
> + spin_lock(&sport->port.lock);
> + imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
> + spin_unlock(&sport->port.lock);
>
> if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ))
> {

Nice catch. Didn't notice this when wrote the check-flood patch, sorry!

Thanks,
-- Sergey Organov

2023-02-13 08:48:17

by Iuliana Prodan

Subject: Re: [PATCH] serial: imx: remove a redundant check

On 2/11/2023 5:45 PM, Tom Rix wrote:
> cpp_check reports
> drivers/tty/serial/imx.c:1207:15: style: Condition 'r_bytes>0' is always true [knownConditionTrueFalse]
> if (r_bytes > 0) {
>
> r_byte is set to
> r_bytes = rx_ring->head - rx_ring->tail;
>
> The head - tail calculation is also done by the earlier check
> if (rx_ring->head <= sg_dma_len(sgl) &&
> rx_ring->head > rx_ring->tail) {
>
> so r_bytes will always be > 0, so the second check is not needed.
>
> Signed-off-by: Tom Rix <[email protected]>

Reviewed-by: Iuliana Prodan <[email protected]>

> ---
> drivers/tty/serial/imx.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 363c77a140f0..523f296d5747 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -1204,11 +1204,9 @@ static void imx_uart_dma_rx_callback(void *data)
> r_bytes = rx_ring->head - rx_ring->tail;
>
> /* If we received something, check for 0xff flood */
> - if (r_bytes > 0) {
> - spin_lock(&sport->port.lock);
> - imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
> - spin_unlock(&sport->port.lock);
> - }
> + spin_lock(&sport->port.lock);
> + imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
> + spin_unlock(&sport->port.lock);
>
> if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) {
>