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[98.183.112.25]) by smtp.gmail.com with ESMTPSA id 5614622812f47-3f0376126c1sm5284695b6e.10.2025.01.15.12.48.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jan 2025 12:48:29 -0800 (PST) From: David Lechner Date: Wed, 15 Jan 2025 14:48:27 -0600 Subject: [PATCH] hwmon: (ltc2991) Fix mixed signed/unsigned in DIV_ROUND_CLOSEST Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250115-hwmon-ltc2991-fix-div-round-closest-v1-1-b4929667e457@baylibre.com> X-B4-Tracking: v=1; b=H4sIABofiGcC/x2N0QqDMAwAf0XybKApdOh+RXxwaZwB10rj3ED89 5U9Hhx3J5gUFYN7c0KRQ01zqkBtA7xM6SmosTJ454MjCrh8XjnhurPve8JZvxj1wJLfKSKv2cR 25FtgF6b50XUEtbQVqeL/MozX9QPdXx0tdQAAAA== X-Change-ID: 20250115-hwmon-ltc2991-fix-div-round-closest-c65c05afb881 To: Antoniu Miclaus , Jean Delvare , Guenter Roeck Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, David Lechner X-Mailer: b4 0.14.2 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 =3D DIV_ROUND_CLOSEST(-100, 3U); results in ret =3D=3D 1431655732 instead of -33. Fixes: 2b9ea4262ae9 ("hwmon: Add driver for ltc2991") Signed-off-by: David Lechner --- drivers/hwmon/ltc2991.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/hwmon/ltc2991.c b/drivers/hwmon/ltc2991.c index 7ca139e4b6aff0b6c3024183e19970b36f927f6e..6d5d4cb846daf3025e55d43cfe3= 11f38bb353621 100644 --- a/drivers/hwmon/ltc2991.c +++ b/drivers/hwmon/ltc2991.c @@ -125,7 +125,7 @@ static int ltc2991_get_curr(struct ltc2991_state *st, u= 32 reg, int channel, =20 /* Vx-Vy, 19.075uV/LSB */ *val =3D DIV_ROUND_CLOSEST(sign_extend32(reg_val, 14) * 19075, - st->r_sense_uohm[channel]); + (s32)st->r_sense_uohm[channel]); =20 return 0; } --- base-commit: dab2734f8e9ecba609d66d1dd087a392a7774c04 change-id: 20250115-hwmon-ltc2991-fix-div-round-closest-c65c05afb881 Best regards, --=20 David Lechner