[Patch v2 3/6] cifs: smbd: Avoid allocating iov on the stack
Steve French
smfrench at gmail.com
Mon Apr 23 17:50:49 UTC 2018
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 at 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 at linuxonhyperv.com> wrote:
>> > From: Long Li <longli at 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 at microsoft.com>
>> > Cc: stable at 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
>> >
>> > --
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>>
>> --
>> Thanks,
>>
>> Steve
>> --
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--
Thanks,
Steve
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