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Date:   Mon, 20 Jul 2020 16:01:51 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Logan Gunthorpe <logang@deltatee.com>
Cc:     linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
        Max Gurtovoy <maxg@mellanox.com>,
        Stephen Bates <sbates@raithlin.com>
Subject: Re: [PATCH v15 1/9] nvme-core: Clear any SGL flags in passthru
 commands
Message-ID: <20200720140151.GA4627@lst.de>
References: <20200716203319.16022-1-logang@deltatee.com> <20200716203319.16022-2-logang@deltatee.com>
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On Thu, Jul 16, 2020 at 02:33:11PM -0600, Logan Gunthorpe wrote:
> The host driver should decide whether to use SGLs or PRPs and they
> currently assume the flags are cleared after the call to
> nvme_setup_cmd(). However, passed-through commands may erroneously
> set these bits; so clear them for all cases.
> 
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
> ---
>  drivers/nvme/host/core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index f49085bcaa42..63a59186e68b 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -759,6 +759,8 @@ blk_status_t nvme_setup_cmd(struct nvme_ns *ns, struct request *req,
>  	case REQ_OP_DRV_IN:
>  	case REQ_OP_DRV_OUT:
>  		memcpy(cmd, nvme_req(req)->cmd, sizeof(*cmd));
> +		/* passthru commands should let the driver set the SGL flags */
> +		cmd->common.flags &= ~NVME_CMD_SGL_ALL;
>  		break;

This probably wants to be split into a little helper like the
other cases.