From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f44.google.com (mail-wm1-f44.google.com [209.85.128.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 09C7A3321A2 for ; Mon, 18 May 2026 10:40:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.44 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779100826; cv=none; b=HvQggSICSv3t5dzrI+7OM1v8PcYr3OPgR0thRAxoFlnA8PSAkVzEWIo7K14PHZW1UkJ57xcoWRTi9yiY/YBqNcORERTTAJVxxvtiqF29EArzry3uHRJCg2wx/22yeNtSlca990xBzdmA4T/KYGTiyD6qCA4xQSFb75ylSEWnpd0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779100826; c=relaxed/simple; bh=nvWmJIaONRzVgGZxYOqc+RrJHx05ZpEkKGknRiyvoD8=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=T0kQJY+gaf8fB/q+zypMPut+BudWajvHLQCg4IAI3Dkh0nt+2/AxqhKyV/erSEm6aEfPrX4YVSwd2e8sgIPivQRI02VbhdzrcNwiKRiNg140VSUuIlm49et4odbNd2Q893y1LG+h40yPof720Tm23ETcJuxnXufJidtgwkfaikc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=YOYYn5lU; arc=none smtp.client-ip=209.85.128.44 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YOYYn5lU" Received: by mail-wm1-f44.google.com with SMTP id 5b1f17b1804b1-48909558b3aso22780805e9.0 for ; Mon, 18 May 2026 03:40:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779100813; x=1779705613; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=KBUJm1g4jrVLHLARnQ410xCyIfZ2+knqUA7xvFczZVo=; b=YOYYn5lUbwDpJJVHgwa+b/uqKmMzzJUm2hIehQT0RfeFic6DPTkEctu4+6yrgoTAaT u9kxlBwiCUk0uHQ4MQ/QBAMPpt5K718IZ1zg5BOo0iQ4OLbx3XAXNVsWFT6PYjxqxiG3 oHvr3OC9nqzpeCxci5FlRGKp37b70XvyPHj0YP2cIbP8cJX6i2a3sWtAjU3noV+2X2PV wkzhPFtUIxCLP4t2y+z/oBQ4ozn1vMXZ6+OkNNIHU/t1RtK8qSsYeCEvIA84yzvQhJL7 MTCcnZhiu8pCfSAOkym3yaNcHT8UovdrqFjblxy1DWYmyiaOdzDrXeutHhDa+t8th2oz CsUA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779100813; x=1779705613; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=KBUJm1g4jrVLHLARnQ410xCyIfZ2+knqUA7xvFczZVo=; b=LEJx1Ikgh28MQJkr7TVsg0nOkqgHuECQCef5iSHMwrsm6bbiTPm6VNLf4Q9CbOczDq 0eYrHYOBLpUtaJrUm1RWB9Ptvv4B4xWVxDYxZTASW6mltGGiF2WTu3i27K74iemALlNE 4+3cXd0UEitm/ycHFDsv8iKnjufirlENvVM1uD1eZp9jdrmAz+BUUdaAA5qvUHNVYD67 MvoBaXZezAakCdTOQBO4mD02eVksx9Iwf2LDJTZQOpRYPRXAOC+PbKPlFQMOjB/8lon/ ks8x3lT6KBuAPGDutJil7B1EhEgVXDjgTC9BPZ0qm0BBbgHb7Uqy1Gh3IphHPeMQkyKY caFg== X-Forwarded-Encrypted: i=1; AFNElJ84tfKUh+94E58TuYU1Mrr6yY5OcFKmoCOsDpi8sUE/lSPcJubTKN1NItC+M9jGFLsj5UxNHY/mHg==@vger.kernel.org X-Gm-Message-State: AOJu0Yz7j0cKhNfE01waiAidLlbQcUSM/YPnOOuGxPoP+kqZiQPzgBIi JDgTO7vvuxbHB6HRK8+MI8TrU+dzsy0HSEWU6zuZwD/mr+yRaiAPX9c0 X-Gm-Gg: Acq92OHm5uh+MlgRYJyi6Ky8uyn7Tp6HcrMMgAr3ZrH40VfxjwrG6h9XKwvKzsmE4Gy f1uM/1G8pI6ZC30YNoPELftudMVKixTre5Tw/QAVs+3GzYvDVhViuwH5+lZjyzti0tZaxM01Q2e JtjDLJSNuqgdVo+xGrHJn0tkh+v5rT1RUtdpfgshlxr34FbA5Ic6ak0lH4ZY+BIRBOV7gvpot8N uJgIlSMrPkMpGrqDNsBI3Q4SXmBdYmAsJ6w5crM/XhJztPmm0bN8xEgwcnweHrlHR+MoiI5l9VZ 1TLrD8eTGg92bJH3y6NsT9xlXRLSAkBfgNA9t858tO8/kGts1W7QZillEUJMZz0zLggF0mbe6H4 8fNs1EjLEDLuGnFZejF7MxpbhuYWcbyHGm++VfPgf8S0EXQwWQhS8jWt3ksTHfXD6D5b3TLBDg9 urDDbI5LXi9QU6RA6C/E0Jf55/W0K777V7TGlPeanAGLZhmmq4fs0shOj+KrGlxQtCp3+u80UqJ 25Cv0GxzpuVNQ== X-Received: by 2002:a05:600c:4fc9:b0:489:1c1f:35df with SMTP id 5b1f17b1804b1-48fe60e58ecmr202920365e9.10.1779100812550; Mon, 18 May 2026 03:40:12 -0700 (PDT) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48fe4c90b27sm255713955e9.8.2026.05.18.03.40.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 May 2026 03:40:12 -0700 (PDT) Date: Mon, 18 May 2026 11:40:10 +0100 From: David Laight To: Pavel Begunkov Cc: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , Alexander Viro , Christian Brauner , Andrew Morton , Sumit Semwal , Christian =?UTF-8?B?S8O2bmln?= , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Jason Gunthorpe Subject: Re: [PATCH v3 02/10] iov_iter: add iterator type for dmabuf maps Message-ID: <20260518114010.6e1f7391@pumpkin> In-Reply-To: <4b2f74e9-3225-47f6-85fe-911720030e35@gmail.com> References: <20a233d2f35274817aa643cc0fe113707eb47e72.1777475843.git.asml.silence@gmail.com> <20260513110557.705bdeed@pumpkin> <20260513142909.03ae6c2b@pumpkin> <4b2f74e9-3225-47f6-85fe-911720030e35@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 18 May 2026 10:24:35 +0100 Pavel Begunkov wrote: > On 5/13/26 14:29, David Laight wrote: > > On Wed, 13 May 2026 11:05:57 +0100 > > David Laight wrote: > > > > ... > >>> @@ -575,7 +575,8 @@ void iov_iter_advance(struct iov_iter *i, size_t size) > >>> { > >>> if (unlikely(i->count < size)) > >>> size = i->count; > >>> - if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i))) { > >>> + if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i)) || > >>> + unlikely(iov_iter_is_dmabuf_map(i))) { > >> > >> > >> Doesn't the extra check add more code to all the non-ubuf cases? ... > >> or writing an iter_is_one_of(i, ITER_xxx, ITER_yyy) define that uses > >> '(1 << i->iter_type) & ((1 << ITER_xxx) | ...)' > > > > This seems to DTRT: > > > > #define _ITER_IS_ONE_OF(iter, t1, t2, t3, t4, t5, t6, t7, t8, ...) \ > > ((1u << (iter)->iter_type) & ((1u << ITER_##t1) | (1u << ITER_##t2) | \ > > (1u << ITER_##t3) | (1u << ITER_##t4) | (1u << ITER_##t5) | \ > > (1u << ITER_##t6) | (1u << ITER_##t7) | (1u << ITER_##t8))) > > #define ITER_IS_ONE_OF(iter, t, ...) \ > > _ITER_IS_ONE_OF(iter, t, ## __VA_ARGS__, t, t, t, t, t, t, t) > > We definitely don't want that, using them directly would've been > much cleaner. > > if (get_type_mask(i) & (TYPE1 | TYPE2)) ... You need to shift all the TYPEn as well. The above condition would become: if (likely(ITER_IS_ONE_OF(i, UBUF, XARRAY, DMABUF_MAP))) { which reads reasonable well. Without the token pasting it becomes: if (likely(ITER_IS_ONE_OF(i, ITER_UBUF, ITER_XARRAY, ITER_DMABUF_MAP))) { and the line starts getting long. Although that version probably needs a check that the mask is constant. -- David >