net/smc/smc_llc.c

   1 /*
   2  *  Shared Memory Communications over RDMA (SMC-R) and RoCE
   3  *
   4  *  Link Layer Control (LLC)
   5  *
   6  *  For now, we only support the necessary "confirm link" functionality
   7  *  which happens for the first RoCE link after successful CLC handshake.
   8  *
   9  *  Copyright IBM Corp. 2016
  10  *
  11  *  Author(s):  Klaus Wacker <Klaus.Wacker@de.ibm.com>
  12  *              Ursula Braun <ubraun@linux.vnet.ibm.com>
  13  */
  14
  15 #include <net/tcp.h>
  16 #include <rdma/ib_verbs.h>
  17
  18 #include "smc.h"
  19 #include "smc_core.h"
  20 #include "smc_clc.h"
  21 #include "smc_llc.h"
  22
  23 /********************************** send *************************************/
  24
  25 struct smc_llc_tx_pend {
  26 };
  27
  28 /* handler for send/transmission completion of an LLC msg */
  29 static void smc_llc_tx_handler(struct smc_wr_tx_pend_priv *pend,
  30                                struct smc_link *link,
  31                                enum ib_wc_status wc_status)
  32 {
  33         /* future work: handle wc_status error for recovery and failover */
  34 }
  35
  36 /**
  37  * smc_llc_add_pending_send() - add LLC control message to pending WQE transmits
  38  * @link: Pointer to SMC link used for sending LLC control message.
  39  * @wr_buf: Out variable returning pointer to work request payload buffer.
  40  * @pend: Out variable returning pointer to private pending WR tracking.
  41  *        It's the context the transmit complete handler will get.
  42  *
  43  * Reserves and pre-fills an entry for a pending work request send/tx.
  44  * Used by mid-level smc_llc_send_msg() to prepare for later actual send/tx.
  45  * Can sleep due to smc_get_ctrl_buf (if not in softirq context).
  46  *
  47  * Return: 0 on success, otherwise an error value.
  48  */
  49 static int smc_llc_add_pending_send(struct smc_link *link,
  50                                     struct smc_wr_buf **wr_buf,
  51                                     struct smc_wr_tx_pend_priv **pend)
  52 {
  53         int rc;
  54
  55         rc = smc_wr_tx_get_free_slot(link, smc_llc_tx_handler, wr_buf, pend);
  56         if (rc < 0)
  57                 return rc;
  58         BUILD_BUG_ON_MSG(
  59                 sizeof(union smc_llc_msg) > SMC_WR_BUF_SIZE,
  60                 "must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_llc_msg)");
  61         BUILD_BUG_ON_MSG(
  62                 sizeof(union smc_llc_msg) != SMC_WR_TX_SIZE,
  63                 "must adapt SMC_WR_TX_SIZE to sizeof(struct smc_llc_msg); if not all smc_wr upper layer protocols use the same message size any more, must start to set link->wr_tx_sges[i].length on each individual smc_wr_tx_send()");
  64         BUILD_BUG_ON_MSG(
  65                 sizeof(struct smc_llc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
  66                 "must increase SMC_WR_TX_PEND_PRIV_SIZE to at least sizeof(struct smc_llc_tx_pend)");
  67         return 0;
  68 }
  69
  70 /* high-level API to send LLC confirm link */
  71 int smc_llc_send_confirm_link(struct smc_link *link, u8 mac[],
  72                               union ib_gid *gid,
  73                               enum smc_llc_reqresp reqresp)
  74 {
  75         struct smc_link_group *lgr = container_of(link, struct smc_link_group,
  76                                                   lnk[SMC_SINGLE_LINK]);
  77         struct smc_llc_msg_confirm_link *confllc;
  78         struct smc_wr_tx_pend_priv *pend;
  79         struct smc_wr_buf *wr_buf;
  80         int rc;
  81
  82         rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
  83         if (rc)
  84                 return rc;
  85         confllc = (struct smc_llc_msg_confirm_link *)wr_buf;
  86         memset(confllc, 0, sizeof(*confllc));
  87         confllc->hd.common.type = SMC_LLC_CONFIRM_LINK;
  88         confllc->hd.length = sizeof(struct smc_llc_msg_confirm_link);
  89         if (reqresp == SMC_LLC_RESP)
  90                 confllc->hd.flags |= SMC_LLC_FLAG_RESP;
  91         memcpy(confllc->sender_mac, mac, ETH_ALEN);
  92         memcpy(confllc->sender_gid, gid, SMC_GID_SIZE);
  93         hton24(confllc->sender_qp_num, link->roce_qp->qp_num);
  94         /* confllc->link_num = SMC_SINGLE_LINK; already done by memset above */
  95         memcpy(confllc->link_uid, lgr->id, SMC_LGR_ID_SIZE);
  96         confllc->max_links = SMC_LINKS_PER_LGR_MAX;
  97         /* send llc message */
  98         rc = smc_wr_tx_send(link, pend);
  99         return rc;
 100 }
 101
 102 /********************************* receive ***********************************/
 103
 104 static void smc_llc_rx_confirm_link(struct smc_link *link,
 105                                     struct smc_llc_msg_confirm_link *llc)
 106 {
 107         struct smc_link_group *lgr;
 108
 109         lgr = container_of(link, struct smc_link_group, lnk[SMC_SINGLE_LINK]);
 110         if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
 111                 if (lgr->role == SMC_SERV)
 112                         complete(&link->llc_confirm_resp);
 113         } else {
 114                 if (lgr->role == SMC_CLNT) {
 115                         link->link_id = llc->link_num;
 116                         complete(&link->llc_confirm);
 117                 }
 118         }
 119 }
 120
 121 static void smc_llc_rx_handler(struct ib_wc *wc, void *buf)
 122 {
 123         struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
 124         union smc_llc_msg *llc = buf;
 125
 126         if (wc->byte_len < sizeof(*llc))
 127                 return; /* short message */
 128         if (llc->raw.hdr.length != sizeof(*llc))
 129                 return; /* invalid message */
 130         if (llc->raw.hdr.common.type == SMC_LLC_CONFIRM_LINK)
 131                 smc_llc_rx_confirm_link(link, &llc->confirm_link);
 132 }
 133
 134 /***************************** init, exit, misc ******************************/
 135
 136 static struct smc_wr_rx_handler smc_llc_rx_handlers[] = {
 137         {
 138                 .handler        = smc_llc_rx_handler,
 139                 .type           = SMC_LLC_CONFIRM_LINK
 140         },
 141         {
 142                 .handler        = NULL,
 143         }
 144 };
 145
 146 int __init smc_llc_init(void)
 147 {
 148         struct smc_wr_rx_handler *handler;
 149         int rc = 0;
 150
 151         for (handler = smc_llc_rx_handlers; handler->handler; handler++) {
 152                 INIT_HLIST_NODE(&handler->list);
 153                 rc = smc_wr_rx_register_handler(handler);
 154                 if (rc)
 155                         break;
 156         }
 157         return rc;
 158 }