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Mon, 09 Mar 2026 09:15:31 -0700 (PDT) Received: from [192.168.1.187] ([148.63.225.166]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48541b7f406sm911005e9.13.2026.03.09.09.15.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 09:15:31 -0700 (PDT) Message-ID: Subject: Re: [PATCH 3/3] iio: imu: bmi160: Remove potential undefined behavior in bmi160_config_pin() From: Nuno =?ISO-8859-1?Q?S=E1?= To: Josh Poimboeuf , x86@kernel.org Cc: linux-kernel@vger.kernel.org, Arnd Bergmann , Peter Zijlstra , Nathan Chancellor , Jonathan Cameron , David Lechner , Nuno =?ISO-8859-1?Q?S=E1?= , Andy Shevchenko Date: Mon, 09 Mar 2026 16:16:16 +0000 In-Reply-To: <84155f1de72b88d2841b16db97f47ffa4b0f747e.1773071992.git.jpoimboe@kernel.org> References: <84155f1de72b88d2841b16db97f47ffa4b0f747e.1773071992.git.jpoimboe@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2026-03-09 at 09:03 -0700, Josh Poimboeuf wrote: > If 'pin' is not one of its expected values, the value of > 'int_out_ctrl_shift' is undefined.=C2=A0 With UBSAN enabled, this causes > Clang to generate undefined behavior, resulting in the following > warning: >=20 > =C2=A0 drivers/iio/imu/bmi160/bmi160_core.o: warning: objtool: bmi160_set= up_irq() falls through to next > function __cfi_bmi160_core_runtime_resume() >=20 > Prevent the UB and improve error handling by adding a BUG() if 'pin' has > an unexpected value. >=20 > Cc: Jonathan Cameron > Cc: David Lechner > CC: Nuno S=C3=A1 > Cc: Andy Shevchenko > Fixes: 895bf81e6bbf ("iio:bmi160: add drdy interrupt support") > Reported-by: Arnd Bergmann > Closes: https://lore.kernel.org/a426d669-58bb-4be1-9eaa-6f3d83109e2d@app.= fastmail.com > Signed-off-by: Josh Poimboeuf > --- > =C2=A0drivers/iio/imu/bmi160/bmi160_core.c | 2 ++ > =C2=A01 file changed, 2 insertions(+) >=20 > diff --git a/drivers/iio/imu/bmi160/bmi160_core.c b/drivers/iio/imu/bmi16= 0/bmi160_core.c > index 5f47708b4c5d..e5326df75e49 100644 > --- a/drivers/iio/imu/bmi160/bmi160_core.c > +++ b/drivers/iio/imu/bmi160/bmi160_core.c > @@ -579,6 +579,8 @@ static int bmi160_config_pin(struct regmap *regmap, e= num bmi160_int_pin pin, > =C2=A0 int_latch_mask =3D BMI160_INT2_LATCH_MASK; > =C2=A0 int_map_mask =3D BMI160_INT2_MAP_DRDY_EN; > =C2=A0 break; > + default: > + BUG(); > =C2=A0 } > =C2=A0 int_out_ctrl_mask =3D BMI160_INT_OUT_CTRL_MASK << int_out_ctrl_shi= ft; > =C2=A0 AFAIK, BUG() is not something we should use lightly so I wonder why having = it rather that a normal 'return -EINVAL'? At the very least, it could be WARN but I still think that's too much for a= device .probe(). Any special reason using BUG()? Also seems like: https://elixir.bootlin.com/linux/v7.0-rc2/source/drivers/iio/imu/bmi160/bmi= 160_core.c#L624 could be improved? Like setting 'pin_name' in the first switch() case. - Nuno S=C3=A1