From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DC33251C3E; Thu, 28 Mar 2024 07:36:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711611376; cv=none; b=Ne2oSMB9GXGCB9HnI+GdBInJPiTwY8OBr/mgzsrT0GUV3oWKhvyi0SzK65vufrEIghE/BEtNT1LFbaZiWjMMZD56wSqf9JGWib9dF7h0Hw4mEKGj/6oRClyTRUkqmswAa9CtvPi8Wimknlj36JUGtbyFkQrdyHaIYL6DpqPJN7w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711611376; c=relaxed/simple; bh=E0xlW2CX/m4Lsu+pWv53RNQvI+T8j1SSWWH4AEJ0ZTE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mToZOxKhhyIDw/RolCw18+XebVFE6udwgCcFUsSyApwuKf/ZoyzTAWAcYXjnOepXzOeVn0QLF+QkJ0tXaKKNADsDeptcothzJRek5p1o2d0f7ZX+Y6HXpRg7eJpopLwVILFPRIR5n5tzUmkP8/wugPOllnE7B1rCO8/8qQ7RPXo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OTsrj5/y; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OTsrj5/y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A64C2C433F1; Thu, 28 Mar 2024 07:36:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711611375; bh=E0xlW2CX/m4Lsu+pWv53RNQvI+T8j1SSWWH4AEJ0ZTE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=OTsrj5/yuI9HrDeYC88Dy5LI7sOBqHTuh8HRW1ucI8jv3M33MU55h60Miw93JHe1n y+uZOcTRtLcQNy+CygyIi9j7DniRqXMfm7QBbf3s8icNKzb9AuEmQVAE4KXePw7scM 6xQopNIUHFyzW/UEB7UxUx5jvEfEAS6gMkIT7M8ohVEgOB/k5lqVhVCs7ioIZypIdk 1Oc9qSo2Dz5Ue3nbX+rqydCPJs7ClA42eLZuNrZP1Ce+k8QUSYhjIDnI+NGrSNfCVV dmgc47avnlbwPCBHkFI7LrlE9LVvOATK0IndzhHUNRIrEYG94hHpvm0IZEF2iT9+Dq PE/4zJlUMK5KA== Message-ID: Date: Thu, 28 Mar 2024 16:36:12 +0900 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] scsi: libsas: Allocation SMP request is aligned to ARCH_DMA_MINALIGN To: Christoph Hellwig Cc: Yihang Li , John Garry , yanaijie@huawei.com, jejb@linux.ibm.com, martin.petersen@oracle.com, chenxiang66@hisilicon.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com, prime.zeng@huawei.com, yangxingui@huawei.com References: <20240326124358.2466259-1-liyihang9@huawei.com> <5b5b9392-7fd2-4c87-8e41-5e54adf20003@kernel.org> <0ba9914d-7060-498a-beac-2b19770e1963@oracle.com> <75df3e2d-10c3-5370-3cd8-fe2fb0ff2acc@huawei.com> <03ed6449-eb57-4a55-b2bf-ecbb9787feca@kernel.org> From: Damien Le Moal Content-Language: en-US Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/28/24 16:29, Christoph Hellwig wrote: > On Thu, Mar 28, 2024 at 04:23:22PM +0900, Damien Le Moal wrote: >> But I thought that the original issue was that some arch have ARCH_DMA_MINALIGN >> down to 8B but hisi driver needs at least 16 ? >> >> So in the end, you need something like: >> >> size = ALIGN(size, max(16, ARCH_DMA_MINALIGN)); >> >> no ? > > I don't think we ever have an 8 byte dma minalign. With 8-byte > aligned addresses dma_mapping_error could run into problems. My bad: it is kmalloc() that can return something aligned to 8B... So "size = ALIGN(size, ARCH_DMA_MINALIGN);" is the right thing to do. -- Damien Le Moal Western Digital Research