Re: [PATCH v4 08/21] xprtrdma: Back off rkey when FAST_REG_MR fails

Chuck Lever
2014-07-22T21:18:35Z

On Jul 22, 2014, at 4:03 PM, Anna Schumaker <Anna.Schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org> wrote:

> On 07/22/2014 10:52 AM, Chuck Lever wrote:
>> If posting a FAST_REG_MR Work Reqeust fails, revert the rkey update
>> to avoid subsequent IB_WC_MW_BIND_ERR completions.
>>
>> Suggested-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
>> Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> Tested-by: Shirley Ma <shirley.ma-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> Tested-by: Devesh Sharma <devesh.sharma-laKkSmNT4hbQT0dZR+AlfA@public.gmane.org>
>> ---
>> include/rdma/ib_verbs.h | 11 +++++++++++
>> net/sunrpc/xprtrdma/verbs.c | 12 +++++-------
>> 2 files changed, 16 insertions(+), 7 deletions(-)
>>
>> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
>> index 7ccef34..c5c7ec6 100644
>> --- a/include/rdma/ib_verbs.h
>> +++ b/include/rdma/ib_verbs.h
>> @@ -2479,6 +2479,17 @@ static inline u32 ib_inc_rkey(u32 rkey)
>> }
>>
>> /**
>> + * ib_dec_rkey - decrements the key portion of the given rkey. Can be used
>> + * when recovering from a local immediate error.
>> + * @rkey - the rkey to decrement.
>> + */
>> +static inline u32 ib_dec_rkey(u32 rkey)
>> +{
>> + const u32 mask = 0x000000ff;
>> + return ((rkey - 1) & mask) | (rkey & ~mask);
>
> ib_inc_rkey() uses the same mask, and ib_update_fast_reg_key() uses !mask. I think this should be a #define constant, rather than hardcoded in four places.

Such a clean up is not related to the change in this patch.

However, it could go as a separate patch, sent from someone
who can test the other current users of ib_inc_rkey() and
ib_update_fast_reg_key().

> Anna
>
>
>> +}
>> +
>> +/**
>> * ib_alloc_mw - Allocates a memory window.
>> * @pd: The protection domain associated with the memory window.
>> * @type: The type of the memory window (1 or 2).
>> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
>> index 8bb7945..394b13f 100644
>> --- a/net/sunrpc/xprtrdma/verbs.c
>> +++ b/net/sunrpc/xprtrdma/verbs.c
>> @@ -1497,13 +1497,12 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
>> struct rpcrdma_frmr *frmr = &mw->r.frmr;
>> struct ib_mr *mr = frmr->fr_mr;
>> struct ib_send_wr invalidate_wr, frmr_wr, *bad_wr, *post_wr;
>> -
>> - u8 key;
>> int len, pageoff;
>> int i, rc;
>> int seg_len;
>> u64 pa;
>> int page_no;
>> + u32 rkey;
>>
>> pageoff = offset_in_page(seg1->mr_offset);
>> seg1->mr_offset -= pageoff; /* start of page */
>> @@ -1558,14 +1557,11 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
>> rc = -EIO;
>> goto out_err;
>> }
>> -
>> - /* Bump the key */
>> - key = (u8)(mr->rkey & 0x000000FF);
>> - ib_update_fast_reg_key(mr, ++key);
>> -
>> frmr_wr.wr.fast_reg.access_flags = (writing ?
>> IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
>> IB_ACCESS_REMOTE_READ);
>> + rkey = ib_inc_rkey(mr->rkey);
>> + ib_update_fast_reg_key(mr, rkey);
>> frmr_wr.wr.fast_reg.rkey = mr->rkey;
>> DECR_CQCOUNT(&r_xprt->rx_ep);
>>
>> @@ -1574,6 +1570,8 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
>> if (rc) {
>> dprintk("RPC: %s: failed ib_post_send for register,"
>> " status %i\n", __func__, rc);
>> + rkey = ib_dec_rkey(mr->rkey);
>> + ib_update_fast_reg_key(mr, rkey);
>> goto out_err;
>> } else {
>> seg1->mr_rkey = mr->rkey;
>>
>

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com

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