[PATCH v2 03/19] svcrdma: Avoid Send Queue overflow

Chuck Lever
2017-06-16T15:20:45Z

Sanity case: Catch the case where more Work Requests are being
posted to the Send Queue than there are Send Queue Entries.

This might happen if a client sends a chunk with more segments than
there are SQEs for the transport. The server can't send that reply,
so the transport will deadlock unless the client drops the RPC.

Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/svc_rdma_rw.c | 5 +++++
net/sunrpc/xprtrdma/svc_rdma_sendto.c | 2 +-
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
index 0cf6202..3b35364 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
@@ -232,6 +232,9 @@ static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc)
struct ib_cqe *cqe;
int ret;

+ if (cc->cc_sqecount > rdma->sc_sq_depth)
+ return -EINVAL;
+
first_wr = NULL;
cqe = &cc->cc_cqe;
list_for_each(tmp, &cc->cc_rwctxts) {
@@ -425,6 +428,7 @@ static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
*
* Returns a non-negative number of bytes the chunk consumed, or
* %-E2BIG if the payload was larger than the Write chunk,
+ * %-EINVAL if client provided too many segments,
* %-ENOMEM if rdma_rw context pool was exhausted,
* %-ENOTCONN if posting failed (connection is lost),
* %-EIO if rdma_rw initialization failed (DMA mapping, etc).
@@ -465,6 +469,7 @@ int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
*
* Returns a non-negative number of bytes the chunk consumed, or
* %-E2BIG if the payload was larger than the Reply chunk,
+ * %-EINVAL if client provided too many segments,
* %-ENOMEM if rdma_rw context pool was exhausted,
* %-ENOTCONN if posting failed (connection is lost),
* %-EIO if rdma_rw initialization failed (DMA mapping, etc).
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index 5ba6d91..19fd01e 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -684,7 +684,7 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
return 0;

err2:
- if (ret != -E2BIG)
+ if (ret != -E2BIG || ret != -EINVAL)
goto err1;

ret = svc_rdma_post_recv(rdma, GFP_KERNEL);