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[73.185.129.58]) by smtp.googlemail.com with ESMTPSA id k4sm1367957ion.29.2021.03.24.10.32.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Mar 2021 10:32:26 -0700 (PDT) Subject: Re: [PATCH net-next] net: ipa: avoid 64-bit modulus To: David Laight , 'Alex Elder' , "davem@davemloft.net" , "kuba@kernel.org" Cc: "rdunlap@infradead.org" , "bjorn.andersson@linaro.org" , "evgreen@chromium.org" , "cpratapa@codeaurora.org" , "subashab@codeaurora.org" , "elder@kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20210323010505.2149882-1-elder@linaro.org> From: Alex Elder Message-ID: <47c870aa-44e5-b88e-61ad-5f3b75350273@linaro.org> Date: Wed, 24 Mar 2021 12:32:25 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/24/21 12:12 PM, David Laight wrote: > I think 'count' is also required to be a power of 2. > so you could have checked 'addr & (size - 1)'. It is required to be, and that is checked elsewhere (in gsi_channel_data_valid()). And yes, size would therefore be a power-of-2, and so your clever test would be a simple test. I'll take that into account when I implement the fix. Thanks for the suggestion. -Alex