[PATCH AUTOSEL for 4.14 014/161] xprtrdma: Fix backchannel allocation of extra rpcrdma_reps

Sasha Levin
2018-04-09T03:29:08Z

From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit d698c4a02ee02053bbebe051322ff427a2dad56a ]

The backchannel code uses rpcrdma_recv_buffer_put to add new reps
to the free rep list. This also decrements rb_recv_count, which
spoofs the receive overrun logic in rpcrdma_buffer_get_rep.

Commit 9b06688bc3b9 ("xprtrdma: Fix additional uses of
spin_lock_irqsave(rb_lock)") replaced the original open-coded
list_add with a call to rpcrdma_recv_buffer_put(), but then a year
later, commit 05c974669ece ("xprtrdma: Fix receive buffer
accounting") added rep accounting to rpcrdma_recv_buffer_put.
It was an oversight to let the backchannel continue to use this
function.

The fix this, let's combine the "add to free list" logic with
rpcrdma_create_rep.

Also, do not allocate RPCRDMA_MAX_BC_REQUESTS rpcrdma_reps in
rpcrdma_buffer_create and then allocate additional rpcrdma_reps in
rpcrdma_bc_setup_reps. Allocating the extra reps during backchannel
set-up is sufficient.

Fixes: 05c974669ece ("xprtrdma: Fix receive buffer accounting")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
net/sunrpc/xprtrdma/backchannel.c | 12 ++----------
net/sunrpc/xprtrdma/verbs.c | 32 +++++++++++++++++++-------------
net/sunrpc/xprtrdma/xprt_rdma.h | 2 +-
3 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c
index 823a781ec89c..25e3602aa41f 100644
--- a/net/sunrpc/xprtrdma/backchannel.c
+++ b/net/sunrpc/xprtrdma/backchannel.c
@@ -74,21 +74,13 @@ out_fail:
static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt,
unsigned int count)
{
- struct rpcrdma_rep *rep;
int rc = 0;

while (count--) {
- rep = rpcrdma_create_rep(r_xprt);
- if (IS_ERR(rep)) {
- pr_err("RPC: %s: reply buffer alloc failed\n",
- __func__);
- rc = PTR_ERR(rep);
+ rc = rpcrdma_create_rep(r_xprt);
+ if (rc)
break;
- }
-
- rpcrdma_recv_buffer_put(rep);
}
-
return rc;
}

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 9e8e1de19b2e..97b9d4f671ac 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -951,10 +951,17 @@ rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
return req;
}

-struct rpcrdma_rep *
+/**
+ * rpcrdma_create_rep - Allocate an rpcrdma_rep object
+ * @r_xprt: controlling transport
+ *
+ * Returns 0 on success or a negative errno on failure.
+ */
+int
rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
{
struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
+ struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
struct rpcrdma_rep *rep;
int rc;

@@ -979,12 +986,18 @@ rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
rep->rr_recv_wr.wr_cqe = &rep->rr_cqe;
rep->rr_recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
rep->rr_recv_wr.num_sge = 1;
- return rep;
+
+ spin_lock(&buf->rb_lock);
+ list_add(&rep->rr_list, &buf->rb_recv_bufs);
+ spin_unlock(&buf->rb_lock);
+ return 0;

out_free:
kfree(rep);
out:
- return ERR_PTR(rc);
+ dprintk("RPC: %s: reply buffer %d alloc failed\n",
+ __func__, rc);
+ return rc;
}

int
@@ -1027,17 +1040,10 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
}

INIT_LIST_HEAD(&buf->rb_recv_bufs);
- for (i = 0; i < buf->rb_max_requests + RPCRDMA_MAX_BC_REQUESTS; i++) {
- struct rpcrdma_rep *rep;
-
- rep = rpcrdma_create_rep(r_xprt);
- if (IS_ERR(rep)) {
- dprintk("RPC: %s: reply buffer %d alloc failed\n",
- __func__, i);
- rc = PTR_ERR(rep);
+ for (i = 0; i <= buf->rb_max_requests; i++) {
+ rc = rpcrdma_create_rep(r_xprt);
+ if (rc)
goto out;
- }
- list_add(&rep->rr_list, &buf->rb_recv_bufs);
}

return 0;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index e26a97d2f922..fcb0b3227ee1 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -550,8 +550,8 @@ int rpcrdma_ep_post_recv(struct rpcrdma_ia *, struct rpcrdma_rep *);
* Buffer calls - xprtrdma/verbs.c
*/
struct rpcrdma_req *rpcrdma_create_req(struct rpcrdma_xprt *);
-struct rpcrdma_rep *rpcrdma_create_rep(struct rpcrdma_xprt *);
void rpcrdma_destroy_req(struct rpcrdma_req *);
+int rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt);
int rpcrdma_buffer_create(struct rpcrdma_xprt *);
void rpcrdma_buffer_destroy(struct rpcrdma_buffer *);

--
2.15.1