On 5/5/08 5:52 PM, "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> On Fri, May 02, 2008 at 11:28:40AM -0500, Tom Tucker wrote:
>> The rdma_read_xdr function did discriminate between no read-list and
> ^^^
> did not?
>
Ack.
>> an error posting the read-list. This results a leak of a page in the
>> context when an asyncrhonous error occurs on the transport.
>>
>> Signed-off-by: Tom Tucker <tom@xxxxxxxxxxxxxxxxxxxxx>
>>
>> ---
>> net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 17 +++++++++++++----
>> 1 files changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
>> b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
>> index f3a108a..0ac375a 100644
>> --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
>> +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
>> @@ -260,11 +260,16 @@ static int rdma_read_max_sge(struct svcxprt_rdma *xprt,
>> int sge_count)
>> * On our side, we need to read into a pagelist. The first page immediately
>> * follows the RPC header.
>> *
>> - * This function returns 1 to indicate success. The data is not yet in
>> + * This function returns:
>> + * 0 - No error and no read-list found.
>> + *
>> + * 1 - Successful read-list processing. The data is not yet in
>> * the pagelist and therefore the RPC request must be deferred. The
>> * I/O completion will enqueue the transport again and
>> * svc_rdma_recvfrom will complete the request.
>> *
>> + * <0 - Error processing/posting read-list.
>> + *
>> * NOTE: The ctxt must not be touched after the last WR has been posted
>> * because the I/O completion processing may occur on another
>> * processor and free / modify the context. Ne touche pas!
>> @@ -398,7 +403,7 @@ next_sge:
>> svc_rdma_put_context(head, 1);
>> head = ctxt;
>> }
>> - return 0;
>> + return err;
>> }
>>
>> return 1;
>> @@ -536,8 +541,12 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
>> * it. Not that in this case, we don't return the RQ credit
>> * until after the read completes.
>> */
>> - if (rdma_read_xdr(rdma_xprt, rmsgp, rqstp, ctxt)) {
>> - svc_xprt_received(xprt);
>> + ret = rdma_read_xdr(rdma_xprt, rmsgp, rqstp, ctxt);
>> + if (ret) {
>> + if (ret > 0)
>> + svc_xprt_received(xprt);
>> + else
>> + svc_rdma_put_context(ctxt, 1);
>> return 0;
>> }
>>
>
> Possibly slightly more straightforward?:
>
> /* Read read-list data. */
> ret = rdma_read_xdr(rdma_xprt, rmsgp, rqstp, ctxt);
> if (ret < 0) {
> svc_rdma_put_context(ctxt, 1);
> return 0;
> }
> if (ret > 0) {
> /*
> * We need to wait; defer the request. Note that in
> * this case, we don't return the RQ credit until after
> * the read completes.
> */
> svc_xprt_received(xprt);
> return 0;
> }
> ...
>
Yep. I rewrote that code three different ways and never liked it. I think
you've got it right first try... :-)
> --b.
> --
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