From: David Lechner Date: Wed, 15 Jan 2025 20:48:27 +0000 (-0600) Subject: hwmon: (ltc2991) Fix mixed signed/unsigned in DIV_ROUND_CLOSEST X-Git-Tag: v6.13~10^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e9b24deb84863c5a77dda5be57b6cb5bf4127b85;p=thirdparty%2Flinux.git hwmon: (ltc2991) Fix mixed signed/unsigned in DIV_ROUND_CLOSEST Fix use of DIV_ROUND_CLOSEST where a possibly negative value is divided by an unsigned type by casting the unsigned type to the signed type of the same size (st->r_sense_uohm[channel] has type of u32). The docs on the DIV_ROUND_CLOSEST macro explain that dividing a negative value by an unsigned type is undefined behavior. The actual behavior is that it converts both values to unsigned before doing the division, for example: int ret = DIV_ROUND_CLOSEST(-100, 3U); results in ret == 1431655732 instead of -33. Fixes: 2b9ea4262ae9 ("hwmon: Add driver for ltc2991") Signed-off-by: David Lechner Link: https://lore.kernel.org/r/20250115-hwmon-ltc2991-fix-div-round-closest-v1-1-b4929667e457@baylibre.com Signed-off-by: Guenter Roeck --- diff --git a/drivers/hwmon/ltc2991.c b/drivers/hwmon/ltc2991.c index 7ca139e4b6aff..6d5d4cb846daf 100644 --- a/drivers/hwmon/ltc2991.c +++ b/drivers/hwmon/ltc2991.c @@ -125,7 +125,7 @@ static int ltc2991_get_curr(struct ltc2991_state *st, u32 reg, int channel, /* Vx-Vy, 19.075uV/LSB */ *val = DIV_ROUND_CLOSEST(sign_extend32(reg_val, 14) * 19075, - st->r_sense_uohm[channel]); + (s32)st->r_sense_uohm[channel]); return 0; }