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[24.205.208.113]) by smtp.gmail.com with ESMTPSA id n8-20020a05620a152800b00648e52be61bsm5437078qkk.37.2022.02.28.13.06.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Feb 2022 13:06:35 -0800 (PST) Subject: Re: [PATCH] iio: scd4x: check return of scd4x_write_and_fetch To: Jonathan Cameron Cc: roan@protonic.nl, lars@metafoo.de, nathan@kernel.org, ndesaulniers@google.com, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev References: <20220227154331.80338-1-trix@redhat.com> <20220227174850.73520e39@jic23-huawei> From: Tom Rix Message-ID: Date: Mon, 28 Feb 2022 13:06:32 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20220227174850.73520e39@jic23-huawei> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On 2/27/22 9:48 AM, Jonathan Cameron wrote: > On Sun, 27 Feb 2022 07:43:31 -0800 > trix@redhat.com wrote: > >> From: Tom Rix >> >> Clang static analysis reports this problem >> scd4x.c:474:10: warning: The left operand of '==' is a >> garbage value >> if (val == 0xff) { >> ~~~ ^ >> val is only set from a successful call to scd4x_write_and_fetch() >> So check it's return. >> >> Fixes: 49d22b695cbb ("drivers: iio: chemical: Add support for Sensirion SCD4x CO2 sensor") >> Signed-off-by: Tom Rix > Good find, but I'd prefer a separate check on ret inline with what the > other error checking paths in that function are doing. > >> --- >> drivers/iio/chemical/scd4x.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/iio/chemical/scd4x.c b/drivers/iio/chemical/scd4x.c >> index 20d4e7584e923..b978330fb761c 100644 >> --- a/drivers/iio/chemical/scd4x.c >> +++ b/drivers/iio/chemical/scd4x.c >> @@ -471,7 +471,7 @@ static ssize_t calibration_forced_value_store(struct device *dev, >> ret = scd4x_write_and_fetch(state, CMD_FRC, arg, &val, sizeof(val)); >> mutex_unlock(&state->lock); >> >> - if (val == 0xff) { >> + if (!ret && val == 0xff) { >> dev_err(dev, "forced calibration has failed"); >> return -EINVAL; >> } > Prefer > > if (ret) > return ret; > > if (val == 0xff) { > dev_err(dev, "... > return -EINVAL; > } ok and the next line can be simplified to return len; Tom > Thanks, > > Jonathan >