From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A4D7BD3E781 for ; Wed, 10 Dec 2025 22:55:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=5yMsgRQi6UiaSbA4vIty8SPZBWLU7FgAy5T/+tZKTOI=; b=y2i0h6ErqEPzy+ zqcZti+emsjKWfp9fqfFsNyVS/8v/51YSpC8NeukzJovzEZ7m/8wPpJga1xQX82SuZoKHtm4K32zx X2hEJI+d6eCw+Gwz1hB3EcJGma8hQ3Zoz2CmYD80pFUBoynkjCnIUG/JbyNo8sMgamAQdXUAAbJTb h1TOEhYJ75HG5A7ojRSrhR2zLbbaXRaILPKIdeO+Tk06WBBt+O9unXKk5r/2gwJme8rvMx9YeI9Jd 3VCoPKwnpQl2rzlEMJpCVnkwEUqbpaYqrJlKnHFzC6XJ+slbgzPTGG7L3Z4qwQ3FEkKmHsm6JABfz IbAY3XiZPfjdlhwzlyPQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTT5G-0000000FwzI-0bEn; Wed, 10 Dec 2025 22:54:58 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTT5F-0000000Fwz7-2597; Wed, 10 Dec 2025 22:54:57 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id AF63A6011E; Wed, 10 Dec 2025 22:54:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48847C4CEF1; Wed, 10 Dec 2025 22:54:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765407296; bh=8JOdnH8KktNBpZMvUsGFkBLybLSALb0U05AElB0cFO4=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=BslJAJRjXviWwZqQk04+V3QQDrmDTUkC45Jv3BiKvpuSlqZ/PhPXfINN6TNP1FBgm /O8W07PM1aA6dZ2tX/6MvQXI/QBbWxqhNWgL4PBWD+DEeKoZg2UlCQMAzGBqzRZsLc 6nktTVq8q2rOs+0zYDkmjN1NGbit7v1Ctr91smzqnKXl+30sGnTbooG+BRUK2cxrJv Z2oxKn9y4kj1teNsPoUAIUq4GrQmvyGQ7rkWAZTZEorZTUi4MKzP4I11qOceqBXOwY KG3c613LwXnUwUAQa2vxWvCSHJRR54w1+jqJnIRhD3GUy/iWVwj9WZi/MQtdjXBNrT +q85oSr3ibLdA== Date: Wed, 10 Dec 2025 16:54:55 -0600 From: Bjorn Helgaas To: Frank Li Cc: Vinod Koul , Manivannan Sadhasivam , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Bjorn Helgaas , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Herbert Xu , "David S. Miller" , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Koichiro Den , Niklas Cassel , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev Subject: Re: [PATCH 6/8] nvmet: pci-epf: Use dmaengine_prep_slave_single_config() API Message-ID: <20251210225455.GA3544539@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251208-dma_prep_config-v1-6-53490c5e1e2a@nxp.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Dec 08, 2025 at 12:09:45PM -0500, Frank Li wrote: > Use the new dmaengine_prep_slave_single_config() API to combine the > configuration and descriptor preparation into a single call. > > Since dmaengine_prep_slave_single_config() performs the configuration > and preparation atomically, the mutex can be removed. > @@ -386,22 +386,16 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf, > return -EINVAL; > } > > - mutex_lock(lock); > - > dma_dev = dmaengine_get_dma_device(chan); > dma_addr = dma_map_single(dma_dev, seg->buf, seg->length, dir); > ret = dma_mapping_error(dma_dev, dma_addr); > if (ret) > - goto unlock; > - > - ret = dmaengine_slave_config(chan, &sconf); > - if (ret) { > - dev_err(dev, "Failed to configure DMA channel\n"); > - goto unmap; > - } > + return ret; > > - desc = dmaengine_prep_slave_single(chan, dma_addr, seg->length, > - sconf.direction, DMA_CTRL_ACK); > + desc = dmaengine_prep_slave_single_config(chan, dma_addr, seg->length, > + sconf.direction, > + DMA_CTRL_ACK, > + &sconf); > if (!desc) { > dev_err(dev, "Failed to prepare DMA\n"); > ret = -EIO; > @@ -423,9 +417,6 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf, > unmap: > dma_unmap_single(dma_dev, dma_addr, seg->length, dir); > > -unlock: > - mutex_unlock(lock); > - I don't know the dmaengine code, but it's not obvious to me what makes dmaengine_prep_slave_single_config() itself atomic, since it doesn't contain any locking. Bjorn