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[60.250.196.139]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b3b5890e04sm20110159c88.2.2026.11.11.17.26.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Nov 2026 17:26:03 -0800 (PST) Message-ID: Date: Thu, 12 Nov 2026 09:26:00 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/2] iio: adc: Add Nuvoton MA35D1 EADC driver To: Andy Shevchenko , Victor Chernyakin Cc: andy@kernel.org, conor+dt@kernel.org, cwweng@nuvoton.com, devicetree@vger.kernel.org, dlechner@baylibre.com, jic23@kernel.org, krzk+dt@kernel.org, linux-arm-kernel@lists.infradead.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, nuno.sa@analog.com, robh@kernel.org References: <20261104091136.151269-3-cwweng.linux@gmail.com> Content-Language: en-US From: Chi-Wen Weng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Andy Shevchenko 於 2026/11/11 下午 10:05 寫道: > On Tue, Nov 10, 2026 at 08:08:03PM -0600, Victor Chernyakin wrote: > > ... > >>> + if (!num_channels) >>> + return dev_err_probe(dev, -ENOENT, "no ADC channels configured\n"); >>> + >>> + if (num_channels > MA35D1_EADC_MAX_EXT_CHANNELS) >>> + return dev_err_probe(dev, -ENOSPC, "too many ADC channels\n"); >>> + >>> + channels = devm_kcalloc(dev, size_add(num_channels, 1), >>> + sizeof(*channels), GFP_KERNEL); >> >> Couldn't size_add() just be regular +? >> (Question to Andy who originally suggested it) >> We've just checked that num_channels is small and won't overflow. > > While that's true, the other aspect(s) of this is in play. Namely we want to > have the same pattern over the kernel that makes code robust (tomorrow some > cases can be modified unnoticed with opening such an issue again) along with > the potential of finding those patterns and update in case of mass-updates > of low-level API, and I have heard for the matter of fact that devm_*alloc*() > are in the plans to move to something like k*alloc_obj*() or k*alloc_flex(). > Thanks Victor and Andy for the discussion. I'll keep size_add() for consistency and future-proofing, as Andy suggested. Thanks, Chi-Wen