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Sat, 10 Jun 2023 23:29:21 +0100 From: David Laight To: 'Andrew Morton' , Lorenzo Stoakes CC: Lu Hongfei , Uladzislau Rezki , Christoph Hellwig , "open list:VMALLOC" , open list , "opensource.kernel@vivo.com" Subject: RE: [PATCH] mm/vmalloc: Replace the ternary conditional operator with min() Thread-Topic: [PATCH] mm/vmalloc: Replace the ternary conditional operator with min() Thread-Index: AQHZm+gKsZ2mMErDwEmVNd3QmnYBSK+Emzhg Date: Sat, 10 Jun 2023 22:29:21 +0000 Message-ID: <84a2c079fcd44b8490eaf039cd20d2bf@AcuMS.aculab.com> References: <20230609061309.42453-1-luhongfei@vivo.com> <832d7c69-ffd5-4764-8ffe-3a02bef0efb0@lucifer.local> <3fc87d60-4e81-4f49-95f0-0503ad5cdf35@lucifer.local> <20230610150809.babdc5a7919258f066c8637e@linux-foundation.org> In-Reply-To: <20230610150809.babdc5a7919258f066c8637e@linux-foundation.org> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 8A272100004 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: aw6h4yqrbmo1bkeanuj3zrdktatrh78d X-HE-Tag: 1686436169-159910 X-HE-Meta: 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 bpheNvm8 /6xw1Zu/Aoo0DYugjQujdo0wW1tIs6iyG+yBhTj0PFC44aIClVHVIAN4/zKLc/yhM3DPFCHNg+x3qTzyRHQsDgPjp/9AdPSEDX/IJiKTr0BhB3L5WYFaUBm+htdkoMwlABaD0azuYpGT9kiTlFyCu1o6/q+iuZ/VRoPeZNyDMDdFdfHIdE3mv2Ac1GRDcjlmze56cRS6pIbGCL7CXO0lCi4auaV7nuERIwSV8C0FxjC8ZM1K5s/jllYtq+Ln1XrCa+BQxJ2YcesNlhh90grGZvHj3HiWYbV1HqkGX1tYBSVTm3l9J4H7YZ8uZ9Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Andrew Morton > Sent: 10 June 2023 23:08 >=20 > On Sat, 10 Jun 2023 22:06:35 +0100 Lorenzo Stoakes w= rote: >=20 > > > > OK, as per the pedantic test bot, you'll need to change this to:- > > > > > > > > num =3D min_t(size_t, remains, PAGE_SIZE); >=20 > PAGE_SIZE is a nuisance. It _usually_ creates the need for a > cast: >=20 > hp2:/usr/src/linux-6.4-rc4> grep -r "min(.*PAGE_SIZE" . | wc -l > 117 > hp2:/usr/src/linux-6.4-rc4> grep -r "min_t(.*PAGE_SIZE" . | wc -l > 279 >=20 > Perhaps it should always have been size_t. >=20 > I suppose we could do >=20 > #define PAGE_SIZE_T (size_t)PAGE_SIZE >=20 > And use that where needed. Mainly because I like the name ;) Or someone take my patches to relax the checks min() does a bit. I think I last posted them in January. Basically: - unsigned v unsigned is always ok. - signed v signed is always ok. - unsigned v signed is ok provided one value is in [0..INT_MAX]. this can be allowed for compile-time constants. The usual 'error case' is unsigned v signed when the values are known (by the person writing the code) to be non-negative. Doing '(x) + 0u + 0ul + 0ull' zero extends the value without ever masking it or 'accidentally' converting a pointer. =09David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales)