BMC/Intel-BMC/linux.git/include/linux/sunrpc/svc_rdma.h, branch dev-5.8

svcrdma: Remove the SVCRDMA_DEBUG macro

2020-05-18T14:21:22+00:00

Clean up: Commit d21b05f101ae ("rdma: SVCRMDA Header File") introduced the SVCRDMA_DEBUG macro, but it doesn't seem to have been used. Signed-off-by: Chuck Lever

svcrdma: Fix backchannel return code

2020-05-18T14:21:21+00:00

Way back when I was writing the RPC/RDMA server-side backchannel code, I misread the TCP backchannel reply handler logic. When svc_tcp_recvfrom() successfully receives a backchannel reply, it does not return -EAGAIN. It sets XPT_DATA and returns zero. Update svc_rdma_recvfrom() to return zero. Here, XPT_DATA doesn't need to be set again: it is set whenever a new message is received, behind a spin lock in a single threaded context. Also, if handling the cb reply is not successful, the message is simply dropped. There's no special message framing to deal with as there is in the TCP case. Now that the handle_bc_reply() return value is ignored, I've removed the dprintk call sites in the error exit of handle_bc_reply() in favor of trace points in other areas that already report the error cases. Signed-off-by: Chuck Lever

svcrdma: Fix leak of svc_rdma_recv_ctxt objects

2020-04-17T16:40:38+00:00

Utilize the xpo_release_rqst transport method to ensure that each rqstp's svc_rdma_recv_ctxt object is released even when the server cannot return a Reply for that rqstp. Without this fix, each RPC whose Reply cannot be sent leaks one svc_rdma_recv_ctxt. This is a 2.5KB structure, a 4KB DMA-mapped Receive buffer, and any pages that might be part of the Reply message. The leak is infrequent unless the network fabric is unreliable or Kerberos is in use, as GSS sequence window overruns, which result in connection loss, are more common on fast transports. Fixes: 3a88092ee319 ("svcrdma: Preserve Receive buffer until svc_rdma_sendto") Signed-off-by: Chuck Lever

svcrdma: Avoid DMA mapping small RPC Replies

2020-03-16T16:04:33+00:00

On some platforms, DMA mapping part of a page is more costly than copying bytes. Indeed, not involving the I/O MMU can help the RPC/RDMA transport scale better for tiny I/Os across more RDMA devices. This is because interaction with the I/O MMU is eliminated for each of these small I/Os. Without the explicit unmapping, the NIC no longer needs to do a costly internal TLB shoot down for buffers that are just a handful of bytes. Since pull-up is now a more a frequent operation, I've introduced a trace point in the pull-up path. It can be used for debugging or user-space tools that count pull-up frequency. Signed-off-by: Chuck Lever

svcrdma: Fix double sync of transport header buffer

2020-03-16T16:04:33+00:00

Performance optimization: Avoid syncing the transport buffer twice when Reply buffer pull-up is necessary. Signed-off-by: Chuck Lever

svcrdma: Refactor chunk list encoders

2020-03-16T16:04:33+00:00

Same idea as the receive-side changes I did a while back: use xdr_stream helpers rather than open-coding the XDR chunk list encoders. This builds the Reply transport header from beginning to end without backtracking. As additional clean-ups, fill in documenting comments for the XDR encoders and sprinkle some trace points in the new encoding functions. Signed-off-by: Chuck Lever

svcrdma: Update synopsis of svc_rdma_map_reply_msg()

2020-03-16T16:04:32+00:00

Preparing for subsequent patches, no behavior change expected. Pass the RPC Call's svc_rdma_recv_ctxt deeper into the sendto() path. This enables passing more information about Requester- provided Write and Reply chunks into those lower-level functions. Signed-off-by: Chuck Lever

svcrdma: Update synopsis of svc_rdma_send_reply_chunk()

2020-03-16T16:04:32+00:00

Preparing for subsequent patches, no behavior change expected. Pass the RPC Call's svc_rdma_recv_ctxt deeper into the sendto() path. This enables passing more information about Requester- provided Write and Reply chunks into the lower-level send functions. Signed-off-by: Chuck Lever

svcrdma: De-duplicate code that locates Write and Reply chunks

2020-03-16T16:04:32+00:00

Cache the locations of the Requester-provided Write list and Reply chunk so that the Send path doesn't need to parse the Call header again. Signed-off-by: Chuck Lever

svcrdma: Use struct xdr_stream to decode ingress transport headers

2020-03-16T16:04:32+00:00

The logic that checks incoming network headers has to be scrupulous. De-duplicate: replace open-coded buffer overflow checks with the use of xdr_stream helpers that are used most everywhere else XDR decoding is done. One minor change to the sanity checks: instead of checking the length of individual segments, cap the length of the whole chunk to be sure it can fit in the set of pages available in rq_pages. This should be a better test of whether the server can handle the chunks in each request. Signed-off-by: Chuck Lever