From: Varun Prakash <varun@chelsio.com>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Christoph Hellwig <hch@lst.de>, linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvmet-tcp: fix data digest pointer calculation
Date: Wed, 27 Oct 2021 20:19:16 +0530 [thread overview]
Message-ID: <20211027144914.GA1851@chelsio.com> (raw)
In-Reply-To: <252308fb-d557-34ce-5c7f-a6307f92b111@grimberg.me>
On Wed, Oct 27, 2021 at 12:49:31PM +0300, Sagi Grimberg wrote:
>
> >>>>diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> >>>>index 07ee347..d641bfa 100644
> >>>>--- a/drivers/nvme/target/tcp.c
> >>>>+++ b/drivers/nvme/target/tcp.c
> >>>>@@ -702,7 +702,7 @@ static int nvmet_try_send_ddgst(struct nvmet_tcp_cmd *cmd, bool last_in_batch)
> >>>> struct nvmet_tcp_queue *queue = cmd->queue;
> >>>> struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
> >>>> struct kvec iov = {
> >>>>- .iov_base = &cmd->exp_ddgst + cmd->offset,
> >>>>+ .iov_base = (u8 *)&cmd->exp_ddgst + cmd->offset,
> >>>
> >>>Wouldn't be the better fix to divide cmd->offset by 4 instead of the
> >>>casts? I can fix this up inline if that is ok.
> >>
> >>Don't really mind, what makes it a better fix?
> >
> >I generally prefer to avoid casts as they paper over bugs.
>
> I'm fine either way.
cmd->offset can have value 0,1,2,3. cmd->offset / 4 will always be 0.
If 2 bytes of digest are transmitted in the first call to kernel_sendmsg()
then in the second call remaining 2 bytes has to be transmitted so data digest
buffer pointer should increase by 2 bytes.
There is one more bug in nvmet_try_send_ddgst() it currently does not check
whether digest is send successfully. For successful digest send
cmd->offset + ret should be equal to NVME_TCP_DIGEST_LENGTH.
next prev parent reply other threads:[~2021-10-27 14:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-25 17:16 [PATCH] nvmet-tcp: fix data digest pointer calculation Varun Prakash
2021-10-26 13:24 ` Sagi Grimberg
2021-10-27 5:57 ` Christoph Hellwig
2021-10-27 7:11 ` Sagi Grimberg
2021-10-27 7:13 ` Christoph Hellwig
2021-10-27 9:49 ` Sagi Grimberg
2021-10-27 14:49 ` Varun Prakash [this message]
2021-10-28 8:26 ` Sagi Grimberg
2021-10-28 10:49 ` Varun Prakash
2021-10-28 14:00 ` Christoph Hellwig
2021-10-28 14:07 ` Sagi Grimberg
2021-10-27 21:37 ` Keith Busch
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