cregit-Linux how code gets into the kernel

Release 4.14 net/9p/trans_rdma.c

Directory: net/9p
 * linux/fs/9p/trans_rdma.c
 * RDMA transport layer based on the trans_fd.c implementation.
 *  Copyright (C) 2008 by Tom Tucker <>
 *  Copyright (C) 2006 by Russ Cox <>
 *  Copyright (C) 2004-2005 by Latchesar Ionkov <>
 *  Copyright (C) 2004-2008 by Eric Van Hensbergen <>
 *  Copyright (C) 1997-2002 by Ron Minnich <>
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  GNU General Public License for more details.
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/in.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/ipv6.h>
#include <linux/kthread.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/un.h>
#include <linux/uaccess.h>
#include <linux/inet.h>
#include <linux/idr.h>
#include <linux/file.h>
#include <linux/parser.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>

#define P9_PORT			5640

#define P9_RDMA_SQ_DEPTH	32

#define P9_RDMA_RQ_DEPTH	32

#define P9_RDMA_SEND_SGE	4

#define P9_RDMA_RECV_SGE	4

#define P9_RDMA_IRD		0

#define P9_RDMA_ORD		0

#define P9_RDMA_TIMEOUT		30000		
/* 30 seconds */

#define P9_RDMA_MAXSIZE		(1024*1024)	
/* 1MB */

 * struct p9_trans_rdma - RDMA transport instance
 * @state: tracks the transport state machine for connection setup and tear down
 * @cm_id: The RDMA CM ID
 * @pd: Protection Domain pointer
 * @qp: Queue Pair pointer
 * @cq: Completion Queue pointer
 * @dm_mr: DMA Memory Region pointer
 * @lkey: The local access only memory region key
 * @timeout: Number of uSecs to wait for connection management events
 * @privport: Whether a privileged port may be used
 * @port: The port to use
 * @sq_depth: The depth of the Send Queue
 * @sq_sem: Semaphore for the SQ
 * @rq_depth: The depth of the Receive Queue.
 * @rq_sem: Semaphore for the RQ
 * @excess_rc : Amount of posted Receive Contexts without a pending request.
 *              See rdma_request()
 * @addr: The remote peer's address
 * @req_lock: Protects the active request list
 * @cm_done: Completion event for connection management tracking

struct p9_trans_rdma {
	enum {
struct rdma_cm_id *cm_id;
struct ib_pd *pd;
struct ib_qp *qp;
struct ib_cq *cq;
long timeout;
bool privport;
u16 port;
int sq_depth;
struct semaphore sq_sem;
int rq_depth;
struct semaphore rq_sem;
atomic_t excess_rc;
struct sockaddr_in addr;
spinlock_t req_lock;

struct completion cm_done;

 * p9_rdma_context - Keeps track of in-process WR
 * @busa: Bus address to unmap when the WR completes
 * @req: Keeps track of requests (send)
 * @rc: Keepts track of replies (receive)
struct p9_rdma_req;

struct p9_rdma_context {
struct ib_cqe cqe;
dma_addr_t busa;
	union {
struct p9_req_t *req;
struct p9_fcall *rc;

 * p9_rdma_opts - Collection of mount options
 * @port: port of connection
 * @sq_depth: The requested depth of the SQ. This really doesn't need
 * to be any deeper than the number of threads used in the client
 * @rq_depth: The depth of the RQ. Should be greater than or equal to SQ depth
 * @timeout: Time to wait in msecs for CM events

struct p9_rdma_opts {
short port;
bool privport;
int sq_depth;
int rq_depth;
long timeout;

 * Option Parsing (code inspired by NFS code)
enum {
	/* Options that take integer arguments */

Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout,
	/* Options that take no argument */

static match_table_t tokens = {
	{Opt_port, "port=%u"},
	{Opt_sq_depth, "sq=%u"},
	{Opt_rq_depth, "rq=%u"},
	{Opt_timeout, "timeout=%u"},
	{Opt_privport, "privport"},
	{Opt_err, NULL},

static int p9_rdma_show_options(struct seq_file *m, struct p9_client *clnt) { struct p9_trans_rdma *rdma = clnt->trans; if (rdma->port != P9_PORT) seq_printf(m, ",port=%u", rdma->port); if (rdma->sq_depth != P9_RDMA_SQ_DEPTH) seq_printf(m, ",sq=%u", rdma->sq_depth); if (rdma->rq_depth != P9_RDMA_RQ_DEPTH) seq_printf(m, ",rq=%u", rdma->rq_depth); if (rdma->timeout != P9_RDMA_TIMEOUT) seq_printf(m, ",timeout=%lu", rdma->timeout); if (rdma->privport) seq_puts(m, ",privport"); return 0; }


David Howells117100.00%1100.00%

/** * parse_opts - parse mount options into rdma options structure * @params: options string passed from mount * @opts: rdma transport-specific structure to parse options into * * Returns 0 upon success, -ERRNO upon failure */
static int parse_opts(char *params, struct p9_rdma_opts *opts) { char *p; substring_t args[MAX_OPT_ARGS]; int option; char *options, *tmp_options; opts->port = P9_PORT; opts->sq_depth = P9_RDMA_SQ_DEPTH; opts->rq_depth = P9_RDMA_RQ_DEPTH; opts->timeout = P9_RDMA_TIMEOUT; opts->privport = false; if (!params) return 0; tmp_options = kstrdup(params, GFP_KERNEL); if (!tmp_options) { p9_debug(P9_DEBUG_ERROR, "failed to allocate copy of option string\n"); return -ENOMEM; } options = tmp_options; while ((p = strsep(&options, ",")) != NULL) { int token; int r; if (!*p) continue; token = match_token(p, tokens, args); if ((token != Opt_err) && (token != Opt_privport)) { r = match_int(&args[0], &option); if (r < 0) { p9_debug(P9_DEBUG_ERROR, "integer field, but no integer?\n"); continue; } } switch (token) { case Opt_port: opts->port = option; break; case Opt_sq_depth: opts->sq_depth = option; break; case Opt_rq_depth: opts->rq_depth = option; break; case Opt_timeout: opts->timeout = option; break; case Opt_privport: opts->privport = true; break; default: continue; } } /* RQ must be at least as large as the SQ */ opts->rq_depth = max(opts->rq_depth, opts->sq_depth); kfree(tmp_options); return 0; }


Tom Tucker23083.94%116.67%
Dominique Martinet259.12%116.67%
Eric Van Hensbergen103.65%116.67%
Simon Derr51.82%116.67%
Joe Perches20.73%116.67%
David Howells20.73%116.67%

static int p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event) { struct p9_client *c = id->context; struct p9_trans_rdma *rdma = c->trans; switch (event->event) { case RDMA_CM_EVENT_ADDR_RESOLVED: BUG_ON(rdma->state != P9_RDMA_INIT); rdma->state = P9_RDMA_ADDR_RESOLVED; break; case RDMA_CM_EVENT_ROUTE_RESOLVED: BUG_ON(rdma->state != P9_RDMA_ADDR_RESOLVED); rdma->state = P9_RDMA_ROUTE_RESOLVED; break; case RDMA_CM_EVENT_ESTABLISHED: BUG_ON(rdma->state != P9_RDMA_ROUTE_RESOLVED); rdma->state = P9_RDMA_CONNECTED; break; case RDMA_CM_EVENT_DISCONNECTED: if (rdma) rdma->state = P9_RDMA_CLOSED; if (c) c->status = Disconnected; break; case RDMA_CM_EVENT_TIMEWAIT_EXIT: break; case RDMA_CM_EVENT_ADDR_CHANGE: case RDMA_CM_EVENT_ROUTE_ERROR: case RDMA_CM_EVENT_DEVICE_REMOVAL: case RDMA_CM_EVENT_MULTICAST_JOIN: case RDMA_CM_EVENT_MULTICAST_ERROR: case RDMA_CM_EVENT_REJECTED: case RDMA_CM_EVENT_CONNECT_REQUEST: case RDMA_CM_EVENT_CONNECT_RESPONSE: case RDMA_CM_EVENT_CONNECT_ERROR: case RDMA_CM_EVENT_ADDR_ERROR: case RDMA_CM_EVENT_UNREACHABLE: c->status = Disconnected; rdma_disconnect(rdma->cm_id); break; default: BUG(); } complete(&rdma->cm_done); return 0; }


Tom Tucker189100.00%1100.00%

static void recv_done(struct ib_cq *cq, struct ib_wc *wc) { struct p9_client *client = cq->cq_context; struct p9_trans_rdma *rdma = client->trans; struct p9_rdma_context *c = container_of(wc->wr_cqe, struct p9_rdma_context, cqe); struct p9_req_t *req; int err = 0; int16_t tag; req = NULL; ib_dma_unmap_single(rdma->cm_id->device, c->busa, client->msize, DMA_FROM_DEVICE); if (wc->status != IB_WC_SUCCESS) goto err_out; err = p9_parse_header(c->rc, NULL, NULL, &tag, 1); if (err) goto err_out; req = p9_tag_lookup(client, tag); if (!req) goto err_out; /* Check that we have not yet received a reply for this request. */ if (unlikely(req->rc)) { pr_err("Duplicate reply for request %d", tag); goto err_out; } req->rc = c->rc; p9_client_cb(client, req, REQ_STATUS_RCVD); out: up(&rdma->rq_sem); kfree(c); return; err_out: p9_debug(P9_DEBUG_ERROR, "req %p err %d status %d\n", req, err, wc->status); rdma->state = P9_RDMA_FLUSHING; client->status = Disconnected; goto out; }


Tom Tucker14563.88%120.00%
Christoph Hellwig5725.11%120.00%
Simon Derr229.69%120.00%
Dominique Martinet20.88%120.00%
Joe Perches10.44%120.00%

static void send_done(struct ib_cq *cq, struct ib_wc *wc) { struct p9_client *client = cq->cq_context; struct p9_trans_rdma *rdma = client->trans; struct p9_rdma_context *c = container_of(wc->wr_cqe, struct p9_rdma_context, cqe); ib_dma_unmap_single(rdma->cm_id->device, c->busa, c->req->tc->size, DMA_TO_DEVICE); up(&rdma->sq_sem); kfree(c); }


Tom Tucker5765.52%133.33%
Christoph Hellwig2731.03%133.33%
Simon Derr33.45%133.33%

static void qp_event_handler(struct ib_event *event, void *context) { p9_debug(P9_DEBUG_ERROR, "QP event %d context %p\n", event->event, context); }


Tom Tucker2175.00%133.33%
Christoph Hellwig621.43%133.33%
Joe Perches13.57%133.33%

static void rdma_destroy_trans(struct p9_trans_rdma *rdma) { if (!rdma) return; if (rdma->qp && !IS_ERR(rdma->qp)) ib_destroy_qp(rdma->qp); if (rdma->pd && !IS_ERR(rdma->pd)) ib_dealloc_pd(rdma->pd); if (rdma->cq && !IS_ERR(rdma->cq)) ib_free_cq(rdma->cq); if (rdma->cm_id && !IS_ERR(rdma->cm_id)) rdma_destroy_id(rdma->cm_id); kfree(rdma); }


Tom Tucker10599.06%150.00%
Christoph Hellwig10.94%150.00%

static int post_recv(struct p9_client *client, struct p9_rdma_context *c) { struct p9_trans_rdma *rdma = client->trans; struct ib_recv_wr wr, *bad_wr; struct ib_sge sge; c->busa = ib_dma_map_single(rdma->cm_id->device, c->rc->sdata, client->msize, DMA_FROM_DEVICE); if (ib_dma_mapping_error(rdma->cm_id->device, c->busa)) goto error; c->cqe.done = recv_done; sge.addr = c->busa; sge.length = client->msize; sge.lkey = rdma->pd->local_dma_lkey; = NULL; wr.wr_cqe = &c->cqe; wr.sg_list = &sge; wr.num_sge = 1; return ib_post_recv(rdma->qp, &wr, &bad_wr); error: p9_debug(P9_DEBUG_ERROR, "EIO\n"); return -EIO; }


Tom Tucker15290.48%125.00%
Christoph Hellwig127.14%125.00%
Jason Gunthorpe31.79%125.00%
Joe Perches10.60%125.00%

static int rdma_request(struct p9_client *client, struct p9_req_t *req) { struct p9_trans_rdma *rdma = client->trans; struct ib_send_wr wr, *bad_wr; struct ib_sge sge; int err = 0; unsigned long flags; struct p9_rdma_context *c = NULL; struct p9_rdma_context *rpl_context = NULL; /* When an error occurs between posting the recv and the send, * there will be a receive context posted without a pending request. * Since there is no way to "un-post" it, we remember it and skip * post_recv() for the next request. * So here, * see if we are this `next request' and need to absorb an excess rc. * If yes, then drop and free our own, and do not recv_post(). **/ if (unlikely(atomic_read(&rdma->excess_rc) > 0)) { if ((atomic_sub_return(1, &rdma->excess_rc) >= 0)) { /* Got one ! */ kfree(req->rc); req->rc = NULL; goto dont_need_post_recv; } else { /* We raced and lost. */ atomic_inc(&rdma->excess_rc); } } /* Allocate an fcall for the reply */ rpl_context = kmalloc(sizeof *rpl_context, GFP_NOFS); if (!rpl_context) { err = -ENOMEM; goto recv_error; } rpl_context->rc = req->rc; /* * Post a receive buffer for this request. We need to ensure * there is a reply buffer available for every outstanding * request. A flushed request can result in no reply for an * outstanding request, so we must keep a count to avoid * overflowing the RQ. */ if (down_interruptible(&rdma->rq_sem)) { err = -EINTR; goto recv_error; } err = post_recv(client, rpl_context); if (err) { p9_debug(P9_DEBUG_FCALL, "POST RECV failed\n"); goto recv_error; } /* remove posted receive buffer from request structure */ req->rc = NULL; dont_need_post_recv: /* Post the request */ c = kmalloc(sizeof *c, GFP_NOFS); if (!c) { err = -ENOMEM; goto send_error; } c->req = req; c->busa = ib_dma_map_single(rdma->cm_id->device, c->req->tc->sdata, c->req->tc->size, DMA_TO_DEVICE); if (ib_dma_mapping_error(rdma->cm_id->device, c->busa)) { err = -EIO; goto send_error; } c->cqe.done = send_done; sge.addr = c->busa; sge.length = c->req->tc->size; sge.lkey = rdma->pd->local_dma_lkey; = NULL; wr.wr_cqe = &c->cqe; wr.opcode = IB_WR_SEND; wr.send_flags = IB_SEND_SIGNALED; wr.sg_list = &sge; wr.num_sge = 1; if (down_interruptible(&rdma->sq_sem)) { err = -EINTR; goto send_error; } /* Mark request as `sent' *before* we actually send it, * because doing if after could erase the REQ_STATUS_RCVD * status in case of a very fast reply. */ req->status = REQ_STATUS_SENT; err = ib_post_send(rdma->qp, &wr, &bad_wr); if (err) goto send_error; /* Success */ return 0; /* Handle errors that happened during or while preparing the send: */ send_error: req->status = REQ_STATUS_ERROR; kfree(c); p9_debug(P9_DEBUG_ERROR, "Error %d in rdma_request()\n", err); /* Ach. * We did recv_post(), but not send. We have one recv_post in excess. */ atomic_inc(&rdma->excess_rc); return err; /* Handle errors that happened during or while preparing post_recv(): */ recv_error: kfree(rpl_context); spin_lock_irqsave(&rdma->req_lock, flags); if (rdma->state < P9_RDMA_CLOSING) { rdma->state = P9_RDMA_CLOSING; spin_unlock_irqrestore(&rdma->req_lock, flags); rdma_disconnect(rdma->cm_id); } else spin_unlock_irqrestore(&rdma->req_lock, flags); return err; }


Tom Tucker34264.04%110.00%
Simon Derr14927.90%440.00%
Davidlohr Bueso A254.68%110.00%
Christoph Hellwig122.25%110.00%
Jason Gunthorpe30.56%110.00%
Aneesh Kumar K.V20.37%110.00%
Joe Perches10.19%110.00%

static void rdma_close(struct p9_client *client) { struct p9_trans_rdma *rdma; if (!client) return; rdma = client->trans; if (!rdma) return; client->status = Disconnected; rdma_disconnect(rdma->cm_id); rdma_destroy_trans(rdma); }


Tom Tucker52100.00%1100.00%

/** * alloc_rdma - Allocate and initialize the rdma transport structure * @opts: Mount options structure */
static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts) { struct p9_trans_rdma *rdma; rdma = kzalloc(sizeof(struct p9_trans_rdma), GFP_KERNEL); if (!rdma) return NULL; rdma->port = opts->port; rdma->privport = opts->privport; rdma->sq_depth = opts->sq_depth; rdma->rq_depth = opts->rq_depth; rdma->timeout = opts->timeout; spin_lock_init(&rdma->req_lock); init_completion(&rdma->cm_done); sema_init(&rdma->sq_sem, rdma->sq_depth); sema_init(&rdma->rq_sem, rdma->rq_depth); atomic_set(&rdma->excess_rc, 0); return rdma; }


Tom Tucker10176.52%125.00%
David Howells1612.12%125.00%
Simon Derr1511.36%250.00%

static int rdma_cancel(struct p9_client *client, struct p9_req_t *req) { /* Nothing to do here. * We will take care of it (if we have to) in rdma_cancelled() */ return 1; }


Tom Tucker1995.00%150.00%
Simon Derr15.00%150.00%

/* A request has been fully flushed without a reply. * That means we have posted one buffer in excess. */
static int rdma_cancelled(struct p9_client *client, struct p9_req_t *req) { struct p9_trans_rdma *rdma = client->trans; atomic_inc(&rdma->excess_rc); return 0; }


Simon Derr36100.00%1100.00%

static int p9_rdma_bind_privport(struct p9_trans_rdma *rdma) { struct sockaddr_in cl = { .sin_family = AF_INET, .sin_addr.s_addr = htonl(INADDR_ANY), }; int port, err = -EINVAL; for (port = P9_DEF_MAX_RESVPORT; port >= P9_DEF_MIN_RESVPORT; port--) { cl.sin_port = htons((ushort)port); err = rdma_bind_addr(rdma->cm_id, (struct sockaddr *)&cl); if (err != -EADDRINUSE) break; } return err; }


Dominique Martinet95100.00%1100.00%

/** * trans_create_rdma - Transport method for creating atransport instance * @client: client instance * @addr: IP address string * @args: Mount options string */
static int rdma_create_trans(struct p9_client *client, const char *addr, char *args) { int err; struct p9_rdma_opts opts; struct p9_trans_rdma *rdma; struct rdma_conn_param conn_param; struct ib_qp_init_attr qp_attr; /* Parse the transport specific mount options */ err = parse_opts(args, &opts); if (err < 0) return err; /* Create and initialize the RDMA transport structure */ rdma = alloc_rdma(&opts); if (!rdma) return -ENOMEM; /* Create the RDMA CM ID */ rdma->cm_id = rdma_create_id(&init_net, p9_cm_event_handler, client, RDMA_PS_TCP, IB_QPT_RC); if (IS_ERR(rdma->cm_id)) goto error; /* Associate the client with the transport */ client->trans = rdma; /* Bind to a privileged port if we need to */ if (opts.privport) { err = p9_rdma_bind_privport(rdma); if (err < 0) { pr_err("%s (%d): problem binding to privport: %d\n", __func__, task_pid_nr(current), -err); goto error; } } /* Resolve the server's address */ rdma->addr.sin_family = AF_INET; rdma->addr.sin_addr.s_addr = in_aton(addr); rdma->addr.sin_port = htons(opts.port); err = rdma_resolve_addr(rdma->cm_id, NULL, (struct sockaddr *)&rdma->addr, rdma->timeout); if (err) goto error; err = wait_for_completion_interruptible(&rdma->cm_done); if (err || (rdma->state != P9_RDMA_ADDR_RESOLVED)) goto error; /* Resolve the route to the server */ err = rdma_resolve_route(rdma->cm_id, rdma->timeout); if (err) goto error; err = wait_for_completion_interruptible(&rdma->cm_done); if (err || (rdma->state != P9_RDMA_ROUTE_RESOLVED)) goto error; /* Create the Completion Queue */ rdma->cq = ib_alloc_cq(rdma->cm_id->device, client, opts.sq_depth + opts.rq_depth + 1, 0, IB_POLL_SOFTIRQ); if (IS_ERR(rdma->cq)) goto error; /* Create the Protection Domain */ rdma->pd = ib_alloc_pd(rdma->cm_id->device, 0); if (IS_ERR(rdma->pd)) goto error; /* Create the Queue Pair */ memset(&qp_attr, 0, sizeof qp_attr); qp_attr.event_handler = qp_event_handler; qp_attr.qp_context = client; qp_attr.cap.max_send_wr = opts.sq_depth; qp_attr.cap.max_recv_wr = opts.rq_depth; qp_attr.cap.max_send_sge = P9_RDMA_SEND_SGE; qp_attr.cap.max_recv_sge = P9_RDMA_RECV_SGE; qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR; qp_attr.qp_type = IB_QPT_RC; qp_attr.send_cq = rdma->cq; qp_attr.recv_cq = rdma->cq; err = rdma_create_qp(rdma->cm_id, rdma->pd, &qp_attr); if (err) goto error; rdma->qp = rdma->cm_id->qp; /* Request a connection */ memset(&conn_param, 0, sizeof(conn_param)); conn_param.private_data = NULL; conn_param.private_data_len = 0; conn_param.responder_resources = P9_RDMA_IRD; conn_param.initiator_depth = P9_RDMA_ORD; err = rdma_connect(rdma->cm_id, &conn_param); if (err) goto error; err = wait_for_completion_interruptible(&rdma->cm_done); if (err || (rdma->state != P9_RDMA_CONNECTED)) goto error; client->status = Connected; return 0; error: rdma_destroy_trans(rdma); return -ENOTCONN; }


Tom Tucker52789.47%228.57%
Dominique Martinet427.13%114.29%
Christoph Hellwig152.55%228.57%
Guy Shapiro30.51%114.29%
Sean Hefty20.34%114.29%

static struct p9_trans_module p9_rdma_trans = { .name = "rdma", .maxsize = P9_RDMA_MAXSIZE, .def = 0, .owner = THIS_MODULE, .create = rdma_create_trans, .close = rdma_close, .request = rdma_request, .cancel = rdma_cancel, .cancelled = rdma_cancelled, .show_options = p9_rdma_show_options, }; /** * p9_trans_rdma_init - Register the 9P RDMA transport driver */
static int __init p9_trans_rdma_init(void) { v9fs_register_trans(&p9_rdma_trans); return 0; }


Tom Tucker18100.00%1100.00%

static void __exit p9_trans_rdma_exit(void) { v9fs_unregister_trans(&p9_rdma_trans); }


Tom Tucker15100.00%1100.00%

module_init(p9_trans_rdma_init); module_exit(p9_trans_rdma_exit); MODULE_AUTHOR("Tom Tucker <>")