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xprtrdma: Serialize credit accounting again

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Commit fe97b47cd6 ("xprtrdma: Use workqueue to process RPC/RDMA
replies") replaced the reply tasklet with a workqueue that allows
RPC replies to be processed in parallel. Thus the credit values in
RPC-over-RDMA replies can be applied in a different order than in
which the server sent them.

To fix this, revert commit eba8ff660b ("xprtrdma: Move credit
update to RPC reply handler"). Reverting is done by hand to
accommodate code changes that have occurred since then.

Fixes: fe97b47cd6 ("xprtrdma: Use workqueue to process . . .")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2016-03-04 11:28:27 -05:00 committed by Anna Schumaker
parent 59aa1f9a3c
commit 23826c7aea
3 changed files with 28 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
net/sunrpc/xprtrdma/rpc_rdma.c
View File

@ -797,7 +797,6 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
__be32 *iptr;
int rdmalen, status, rmerr;
unsigned long cwnd;
u32 credits;
dprintk("RPC: %s: incoming rep %p\n", __func__, rep);
@ -928,15 +927,9 @@ out:
if (req->rl_nchunks)
r_xprt->rx_ia.ri_ops->ro_unmap_sync(r_xprt, req);
credits = be32_to_cpu(headerp->rm_credit);
if (credits == 0)
credits = 1; /* don't deadlock */
else if (credits > r_xprt->rx_buf.rb_max_requests)
credits = r_xprt->rx_buf.rb_max_requests;
spin_lock_bh(&xprt->transport_lock);
cwnd = xprt->cwnd;
xprt->cwnd = credits << RPC_CWNDSHIFT;
xprt->cwnd = atomic_read(&r_xprt->rx_buf.rb_credits) << RPC_CWNDSHIFT;
if (xprt->cwnd > cwnd)
xprt_release_rqst_cong(rqst->rq_task);

27
net/sunrpc/xprtrdma/verbs.c
View File

@ -190,6 +190,28 @@ rpcrdma_receive_worker(struct work_struct *work)
rpcrdma_reply_handler(rep);
}
/* Perform basic sanity checking to avoid using garbage
* to update the credit grant value.
*/
static void
rpcrdma_update_granted_credits(struct rpcrdma_rep *rep)
{
struct rpcrdma_msg *rmsgp = rdmab_to_msg(rep->rr_rdmabuf);
struct rpcrdma_buffer *buffer = &rep->rr_rxprt->rx_buf;
u32 credits;
if (rep->rr_len < RPCRDMA_HDRLEN_ERR)
return;
credits = be32_to_cpu(rmsgp->rm_credit);
if (credits == 0)
credits = 1; /* don't deadlock */
else if (credits > buffer->rb_max_requests)
credits = buffer->rb_max_requests;
atomic_set(&buffer->rb_credits, credits);
}
static void
rpcrdma_recvcq_process_wc(struct ib_wc *wc)
{
@ -211,7 +233,8 @@ rpcrdma_recvcq_process_wc(struct ib_wc *wc)
ib_dma_sync_single_for_cpu(rep->rr_device,
rdmab_addr(rep->rr_rdmabuf),
rep->rr_len, DMA_FROM_DEVICE);
prefetch(rdmab_to_msg(rep->rr_rdmabuf));
rpcrdma_update_granted_credits(rep);
out_schedule:
queue_work(rpcrdma_receive_wq, &rep->rr_work);
@ -330,6 +353,7 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
connected:
dprintk("RPC: %s: %sconnected\n",
__func__, connstate > 0 ? "" : "dis");
atomic_set(&xprt->rx_buf.rb_credits, 1);
ep->rep_connected = connstate;
rpcrdma_conn_func(ep);
wake_up_all(&ep->rep_connect_wait);
@ -943,6 +967,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
buf->rb_max_requests = r_xprt->rx_data.max_requests;
buf->rb_bc_srv_max_requests = 0;
spin_lock_init(&buf->rb_lock);
atomic_set(&buf->rb_credits, 1);
rc = ia->ri_ops->ro_init(r_xprt);
if (rc)

1
net/sunrpc/xprtrdma/xprt_rdma.h
View File

@ -311,6 +311,7 @@ struct rpcrdma_buffer {
struct list_head rb_send_bufs;
struct list_head rb_recv_bufs;
u32 rb_max_requests;
atomic_t rb_credits; /* most recent credit grant */
u32 rb_bc_srv_max_requests;
spinlock_t rb_reqslock; /* protect rb_allreqs */