On 01/05/2024 17:41, Douglas Anderson wrote:
The mipi_dsi_generic_write_seq() macro makes a call to mipi_dsi_generic_write() which returns a type ssize_t. The macro then stores it in an int and checks to see if it's negative. This could theoretically be a problem if "ssize_t" is larger than "int".To see the issue, imagine that "ssize_t" is 32-bits and "int" is 16-bits, you could see a problem if there was some code out there that looked like: mipi_dsi_generic_write_seq(dsi, <32768 bytes as arguments>); ...since we'd get back that 32768 bytes were transferred and 32768 stored in a 16-bit int would look negative. Though there are no callsites where we'd actually hit this (even if "int" was only 16-bit), it's cleaner to make the types match so let's fix it. Fixes: a9015ce59320 ("drm/mipi-dsi: Add a mipi_dsi_dcs_write_seq() macro") Signed-off-by: Douglas Anderson <diand...@chromium.org> --- Changes in v3: - Use %zd in print instead of casting errors to int. Changes in v2: - New include/drm/drm_mipi_dsi.h | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h index 70ce0b8cbc68..e0f56564bf97 100644 --- a/include/drm/drm_mipi_dsi.h +++ b/include/drm/drm_mipi_dsi.h @@ -314,17 +314,17 @@ int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi, * @dsi: DSI peripheral device * @seq: buffer containing the payload */ -#define mipi_dsi_generic_write_seq(dsi, seq...) \ - do { \ - static const u8 d[] = { seq }; \ - struct device *dev = &dsi->dev; \ - int ret; \ - ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \ - if (ret < 0) { \ - dev_err_ratelimited(dev, "transmit data failed: %d\n", \ - ret); \ - return ret; \ - } \ +#define mipi_dsi_generic_write_seq(dsi, seq...) \ + do { \ + static const u8 d[] = { seq }; \ + struct device *dev = &dsi->dev; \ + ssize_t ret; \ + ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \ + if (ret < 0) { \ + dev_err_ratelimited(dev, "transmit data failed: %zd\n", \ + ret); \ + return ret; \ + } \ } while (0)/**
Reviewed-by: Neil Armstrong <neil.armstr...@linaro.org>
