Commit 23826c7a authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
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xprtrdma: Serialize credit accounting again 



Commit fe97b47c ("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 eba8ff66 ("xprtrdma: Move credit
update to RPC reply handler"). Reverting is done by hand to
accommodate code changes that have occurred since then.

Fixes: fe97b47c ("xprtrdma: Use workqueue to process . . .")
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Reviewed-by: default avatarSagi Grimberg <sagig@mellanox.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 59aa1f9a

net/sunrpc/xprtrdma/rpc_rdma.c

+1 −8
Original line number Diff line number Diff line
@@ -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);

net/sunrpc/xprtrdma/verbs.c

+26 −1
Original line number Diff line number Diff line
@@ -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)

net/sunrpc/xprtrdma/xprt_rdma.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

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