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author | Chuck Lever <chuck.lever@oracle.com> | 2015-10-24 21:27:43 (GMT) |
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committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2015-11-02 18:45:15 (GMT) |
commit | f531a5dbc451afb66e9d6c71a69e8358d1847969 (patch) | |
tree | 0a48b07469088a397226ba0be3821522d5a16221 /net/sunrpc/xprtrdma/backchannel.c | |
parent | 42e5c3e2725ba0c0affc1fc8a6aa1d5cf31ecb75 (diff) | |
download | linux-f531a5dbc451afb66e9d6c71a69e8358d1847969.tar.xz |
xprtrdma: Pre-allocate backward rpc_rqst and send/receive buffers
xprtrdma's backward direction send and receive buffers are the same
size as the forechannel's inline threshold, and must be pre-
registered.
The consumer has no control over which receive buffer the adapter
chooses to catch an incoming backwards-direction call. Any receive
buffer can be used for either a forward reply or a backward call.
Thus both types of RPC message must all be the same size.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Tested-By: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net/sunrpc/xprtrdma/backchannel.c')
-rw-r--r-- | net/sunrpc/xprtrdma/backchannel.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c new file mode 100644 index 0000000..3d01b32 --- /dev/null +++ b/net/sunrpc/xprtrdma/backchannel.c @@ -0,0 +1,206 @@ +/* + * Copyright (c) 2015 Oracle. All rights reserved. + * + * Support for backward direction RPCs on RPC/RDMA. + */ + +#include <linux/module.h> + +#include "xprt_rdma.h" + +#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) +# define RPCDBG_FACILITY RPCDBG_TRANS +#endif + +static void rpcrdma_bc_free_rqst(struct rpcrdma_xprt *r_xprt, + struct rpc_rqst *rqst) +{ + struct rpcrdma_buffer *buf = &r_xprt->rx_buf; + struct rpcrdma_req *req = rpcr_to_rdmar(rqst); + + spin_lock(&buf->rb_reqslock); + list_del(&req->rl_all); + spin_unlock(&buf->rb_reqslock); + + rpcrdma_destroy_req(&r_xprt->rx_ia, req); + + kfree(rqst); +} + +static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt, + struct rpc_rqst *rqst) +{ + struct rpcrdma_ia *ia = &r_xprt->rx_ia; + struct rpcrdma_regbuf *rb; + struct rpcrdma_req *req; + struct xdr_buf *buf; + size_t size; + + req = rpcrdma_create_req(r_xprt); + if (!req) + return -ENOMEM; + req->rl_backchannel = true; + + size = RPCRDMA_INLINE_WRITE_THRESHOLD(rqst); + rb = rpcrdma_alloc_regbuf(ia, size, GFP_KERNEL); + if (IS_ERR(rb)) + goto out_fail; + req->rl_rdmabuf = rb; + + size += RPCRDMA_INLINE_READ_THRESHOLD(rqst); + rb = rpcrdma_alloc_regbuf(ia, size, GFP_KERNEL); + if (IS_ERR(rb)) + goto out_fail; + rb->rg_owner = req; + req->rl_sendbuf = rb; + /* so that rpcr_to_rdmar works when receiving a request */ + rqst->rq_buffer = (void *)req->rl_sendbuf->rg_base; + + buf = &rqst->rq_snd_buf; + buf->head[0].iov_base = rqst->rq_buffer; + buf->head[0].iov_len = 0; + buf->tail[0].iov_base = NULL; + buf->tail[0].iov_len = 0; + buf->page_len = 0; + buf->len = 0; + buf->buflen = size; + + return 0; + +out_fail: + rpcrdma_bc_free_rqst(r_xprt, rqst); + return -ENOMEM; +} + +/* Allocate and add receive buffers to the rpcrdma_buffer's + * existing list of rep's. These are released when the + * transport is destroyed. + */ +static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt, + unsigned int count) +{ + struct rpcrdma_buffer *buffers = &r_xprt->rx_buf; + struct rpcrdma_rep *rep; + unsigned long flags; + 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); + break; + } + + spin_lock_irqsave(&buffers->rb_lock, flags); + list_add(&rep->rr_list, &buffers->rb_recv_bufs); + spin_unlock_irqrestore(&buffers->rb_lock, flags); + } + + return rc; +} + +/** + * xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests + * @xprt: transport associated with these backchannel resources + * @reqs: number of concurrent incoming requests to expect + * + * Returns 0 on success; otherwise a negative errno + */ +int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs) +{ + struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); + struct rpcrdma_buffer *buffer = &r_xprt->rx_buf; + struct rpc_rqst *rqst; + unsigned int i; + int rc; + + /* The backchannel reply path returns each rpc_rqst to the + * bc_pa_list _after_ the reply is sent. If the server is + * faster than the client, it can send another backward + * direction request before the rpc_rqst is returned to the + * list. The client rejects the request in this case. + * + * Twice as many rpc_rqsts are prepared to ensure there is + * always an rpc_rqst available as soon as a reply is sent. + */ + for (i = 0; i < (reqs << 1); i++) { + rqst = kzalloc(sizeof(*rqst), GFP_KERNEL); + if (!rqst) { + pr_err("RPC: %s: Failed to create bc rpc_rqst\n", + __func__); + goto out_free; + } + + rqst->rq_xprt = &r_xprt->rx_xprt; + INIT_LIST_HEAD(&rqst->rq_list); + INIT_LIST_HEAD(&rqst->rq_bc_list); + + if (rpcrdma_bc_setup_rqst(r_xprt, rqst)) + goto out_free; + + spin_lock_bh(&xprt->bc_pa_lock); + list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); + spin_unlock_bh(&xprt->bc_pa_lock); + } + + rc = rpcrdma_bc_setup_reps(r_xprt, reqs); + if (rc) + goto out_free; + + rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs); + if (rc) + goto out_free; + + buffer->rb_bc_srv_max_requests = reqs; + request_module("svcrdma"); + + return 0; + +out_free: + xprt_rdma_bc_destroy(xprt, reqs); + + pr_err("RPC: %s: setup backchannel transport failed\n", __func__); + return -ENOMEM; +} + +/** + * xprt_rdma_bc_destroy - Release resources for handling backchannel requests + * @xprt: transport associated with these backchannel resources + * @reqs: number of incoming requests to destroy; ignored + */ +void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs) +{ + struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); + struct rpc_rqst *rqst, *tmp; + + spin_lock_bh(&xprt->bc_pa_lock); + list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { + list_del(&rqst->rq_bc_pa_list); + spin_unlock_bh(&xprt->bc_pa_lock); + + rpcrdma_bc_free_rqst(r_xprt, rqst); + + spin_lock_bh(&xprt->bc_pa_lock); + } + spin_unlock_bh(&xprt->bc_pa_lock); +} + +/** + * xprt_rdma_bc_free_rqst - Release a backchannel rqst + * @rqst: request to release + */ +void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) +{ + struct rpc_xprt *xprt = rqst->rq_xprt; + + smp_mb__before_atomic(); + WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state)); + clear_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); + smp_mb__after_atomic(); + + spin_lock_bh(&xprt->bc_pa_lock); + list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); + spin_unlock_bh(&xprt->bc_pa_lock); +} |