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References: <20180417191710.14855-1-longli@linuxonhyperv.com>
 <20180417191710.14855-3-longli@linuxonhyperv.com> <CAH2r5mv65CGR04f3Z20aRBufisPon5Ptvqk++zii3YT=GN8epQ@mail.gmail.com>
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From:   Steve French <smfrench@gmail.com>
Date:   Mon, 23 Apr 2018 12:50:49 -0500
Message-ID: <CAH2r5mtNNGaqH_XteEtzi+GVTB1NFbbwnXBHLygcYMzG2EVdVA@mail.gmail.com>
Subject: Re: [Patch v2 3/6] cifs: smbd: Avoid allocating iov on the stack
To:     Long Li <longli@microsoft.com>
Cc:     CIFS <linux-cifs@vger.kernel.org>,
        samba-technical <samba-technical@lists.samba.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
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I am ok with the other style warning - so I just fixed up the one
error (see attached) and merged into cifs-2.6.git for-next

That leaves two more from your series to review (and for others to
review).  Let's just focus on those two.


On Mon, Apr 23, 2018 at 12:33 PM, Long Li <longli@microsoft.com> wrote:
>> Subject: Re: [Patch v2 3/6] cifs: smbd: Avoid allocating iov on the stack
>>
>> Didn't see any obvious problems, but can you fix the checkpatch warnings
>> and resend to the list (I am more concerned about the last two warnings
>> rather than the first one).
>
> Yes, I will fix it and resend.
>
>>
>> $ scripts/checkpatch.pl 0001-cifs-smbd-Avoid-allocating-iov-on-the-
>> stack.patch
>> WARNING: line over 80 characters
>> #60: FILE: fs/cifs/smbdirect.c:2106:
>> +        log_write(ERR, "expected the pdu length in 1st iov, but got
>> 0x%lu\n", rqst->rq_iov[0].iov_len);
>>
>> ERROR: Prefixing 0x with decimal output is defective
>> #60: FILE: fs/cifs/smbdirect.c:2106:
>> +        log_write(ERR, "expected the pdu length in 1st iov, but got
>> 0x%lu\n", rqst->rq_iov[0].iov_len);
>>
>> WARNING: braces {} are not necessary for single statement blocks
>> #69: FILE: fs/cifs/smbdirect.c:2112:
>> +    for (i = 0; i < rqst->rq_nvec-1; i++) {
>>          buflen += iov[i].iov_len;
>>      }
>>
>> total: 1 errors, 2 warnings, 65 lines checked
>>
>> NOTE: For some of the reported defects, checkpatch may be able to
>>       mechanically convert to the typical style using --fix or --fix-inplace.
>>
>> 0001-cifs-smbd-Avoid-allocating-iov-on-the-stack.patch has style problems,
>> please review.
>>
>> On Tue, Apr 17, 2018 at 2:17 PM, Long Li <longli@linuxonhyperv.com> wrote:
>> > From: Long Li <longli@microsoft.com>
>> >
>> > It's not necessary to allocate another iov when going through the
>> > buffers in smbd_send() through RDMA send.
>> >
>> > Remove it to reduce stack size.
>> >
>> > Signed-off-by: Long Li <longli@microsoft.com>
>> > Cc: stable@vger.kernel.org
>> > ---
>> >  fs/cifs/smbdirect.c | 36 ++++++++++++------------------------
>> >  1 file changed, 12 insertions(+), 24 deletions(-)
>> >
>> > diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c index
>> > b5c6c0d..f575e9a 100644
>> > --- a/fs/cifs/smbdirect.c
>> > +++ b/fs/cifs/smbdirect.c
>> > @@ -2088,7 +2088,7 @@ int smbd_send(struct smbd_connection *info,
>> struct smb_rqst *rqst)
>> >         int start, i, j;
>> >         int max_iov_size =
>> >                 info->max_send_size - sizeof(struct smbd_data_transfer);
>> > -       struct kvec iov[SMBDIRECT_MAX_SGE];
>> > +       struct kvec *iov;
>> >         int rc;
>> >
>> >         info->smbd_send_pending++;
>> > @@ -2099,32 +2099,20 @@ int smbd_send(struct smbd_connection *info,
>> struct smb_rqst *rqst)
>> >         }
>> >
>> >         /*
>> > -        * This usually means a configuration error
>> > -        * We use RDMA read/write for packet size >
>> rdma_readwrite_threshold
>> > -        * as long as it's properly configured we should never get into this
>> > -        * situation
>> > -        */
>> > -       if (rqst->rq_nvec + rqst->rq_npages > SMBDIRECT_MAX_SGE) {
>> > -               log_write(ERR, "maximum send segment %x exceeding %x\n",
>> > -                        rqst->rq_nvec + rqst->rq_npages, SMBDIRECT_MAX_SGE);
>> > -               rc = -EINVAL;
>> > -               goto done;
>> > -       }
>> > -
>> > -       /*
>> > -        * Remove the RFC1002 length defined in MS-SMB2 section 2.1
>> > -        * It is used only for TCP transport
>> > +        * Skip the RFC1002 length defined in MS-SMB2 section 2.1
>> > +        * It is used only for TCP transport in the iov[0]
>> >          * In future we may want to add a transport layer under protocol
>> >          * layer so this will only be issued to TCP transport
>> >          */
>> > -       iov[0].iov_base = (char *)rqst->rq_iov[0].iov_base + 4;
>> > -       iov[0].iov_len = rqst->rq_iov[0].iov_len - 4;
>> > -       buflen += iov[0].iov_len;
>> > +
>> > +       if (rqst->rq_iov[0].iov_len != 4) {
>> > +               log_write(ERR, "expected the pdu length in 1st iov, but got
>> 0x%lu\n", rqst->rq_iov[0].iov_len);
>> > +               return -EINVAL;
>> > +       }
>> > +       iov = &rqst->rq_iov[1];
>> >
>> >         /* total up iov array first */
>> > -       for (i = 1; i < rqst->rq_nvec; i++) {
>> > -               iov[i].iov_base = rqst->rq_iov[i].iov_base;
>> > -               iov[i].iov_len = rqst->rq_iov[i].iov_len;
>> > +       for (i = 0; i < rqst->rq_nvec-1; i++) {
>> >                 buflen += iov[i].iov_len;
>> >         }
>> >
>> > @@ -2197,14 +2185,14 @@ int smbd_send(struct smbd_connection *info,
>> struct smb_rqst *rqst)
>> >                                                 goto done;
>> >                                 }
>> >                                 i++;
>> > -                               if (i == rqst->rq_nvec)
>> > +                               if (i == rqst->rq_nvec-1)
>> >                                         break;
>> >                         }
>> >                         start = i;
>> >                         buflen = 0;
>> >                 } else {
>> >                         i++;
>> > -                       if (i == rqst->rq_nvec) {
>> > +                       if (i == rqst->rq_nvec-1) {
>> >                                 /* send out all remaining vecs */
>> >                                 remaining_data_length -= buflen;
>> >                                 log_write(INFO,
>> > --
>> > 2.7.4
>> >
>> > --
>> > To unsubscribe from this list: send the line "unsubscribe linux-cifs"
>> > in the body of a message to majordomo@vger.kernel.org More
>> majordomo
>> > info at
>> >
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>> > ernel.org%2Fmajordomo-
>> info.html&data=02%7C01%7Clongli%40microsoft.com%
>> >
>> 7C23fbdbb0598a497f624708d5a92f6435%7C72f988bf86f141af91ab2d7cd011d
>> b47%
>> >
>> 7C1%7C0%7C636600943380887988&sdata=imh9cWDQQEXqxHdUrCuEykgiLfKs
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>>
>>
>> --
>> Thanks,
>>
>> Steve
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the
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>> rI%3D&reserved=0


-- 
Thanks,

Steve

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