net/smc/smc_cdc.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Shared Memory Communications over RDMA (SMC-R) and RoCE
   4  *
   5  * Connection Data Control (CDC)
   6  *
   7  * Copyright IBM Corp. 2016
   8  *
   9  * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
  10  */
  11
  12 #ifndef SMC_CDC_H
  13 #define SMC_CDC_H
  14
  15 #include <linux/kernel.h> /* max_t */
  16 #include <linux/atomic.h>
  17 #include <linux/in.h>
  18 #include <linux/compiler.h>
  19
  20 #include "smc.h"
  21 #include "smc_core.h"
  22 #include "smc_wr.h"
  23
  24 #define SMC_CDC_MSG_TYPE                0xFE
  25
  26 /* in network byte order */
  27 union smc_cdc_cursor {          /* SMC cursor */
  28         struct {
  29                 __be16  reserved;
  30                 __be16  wrap;
  31                 __be32  count;
  32         };
  33 #ifdef KERNEL_HAS_ATOMIC64
  34         atomic64_t      acurs;          /* for atomic processing */
  35 #else
  36         u64             acurs;          /* for atomic processing */
  37 #endif
  38 } __aligned(8);
  39
  40 /* in network byte order */
  41 struct smc_cdc_msg {
  42         struct smc_wr_rx_hdr            common; /* .type = 0xFE */
  43         u8                              len;    /* 44 */
  44         __be16                          seqno;
  45         __be32                          token;
  46         union smc_cdc_cursor            prod;
  47         union smc_cdc_cursor            cons;   /* piggy backed "ack" */
  48         struct smc_cdc_producer_flags   prod_flags;
  49         struct smc_cdc_conn_state_flags conn_state_flags;
  50         u8                              reserved[18];
  51 } __packed;                                     /* format defined in RFC7609 */
  52
  53 /* CDC message for SMC-D */
  54 struct smcd_cdc_msg {
  55         struct smc_wr_rx_hdr common;    /* Type = 0xFE */
  56         u8 res1[7];
  57         u16 prod_wrap;
  58         u32 prod_count;
  59         u8 res2[2];
  60         u16 cons_wrap;
  61         u32 cons_count;
  62         struct smc_cdc_producer_flags   prod_flags;
  63         struct smc_cdc_conn_state_flags conn_state_flags;
  64         u8 res3[8];
  65 } __packed;
  66
  67 static inline bool smc_cdc_rxed_any_close(struct smc_connection *conn)
  68 {
  69         return conn->local_rx_ctrl.conn_state_flags.peer_conn_abort ||
  70                conn->local_rx_ctrl.conn_state_flags.peer_conn_closed;
  71 }
  72
  73 static inline bool smc_cdc_rxed_any_close_or_senddone(
  74         struct smc_connection *conn)
  75 {
  76         return smc_cdc_rxed_any_close(conn) ||
  77                conn->local_rx_ctrl.conn_state_flags.peer_done_writing;
  78 }
  79
  80 static inline void smc_curs_add(int size, union smc_host_cursor *curs,
  81                                 int value)
  82 {
  83         curs->count += value;
  84         if (curs->count >= size) {
  85                 curs->wrap++;
  86                 curs->count -= size;
  87         }
  88 }
  89
  90 /* SMC cursors are 8 bytes long and require atomic reading and writing */
  91 static inline u64 smc_curs_read(union smc_host_cursor *curs,
  92                                 struct smc_connection *conn)
  93 {
  94 #ifndef KERNEL_HAS_ATOMIC64
  95         unsigned long flags;
  96         u64 ret;
  97
  98         spin_lock_irqsave(&conn->acurs_lock, flags);
  99         ret = curs->acurs;
 100         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 101         return ret;
 102 #else
 103         return atomic64_read(&curs->acurs);
 104 #endif
 105 }
 106
 107 /* Copy cursor src into tgt */
 108 static inline void smc_curs_copy(union smc_host_cursor *tgt,
 109                                  union smc_host_cursor *src,
 110                                  struct smc_connection *conn)
 111 {
 112 #ifndef KERNEL_HAS_ATOMIC64
 113         unsigned long flags;
 114
 115         spin_lock_irqsave(&conn->acurs_lock, flags);
 116         tgt->acurs = src->acurs;
 117         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 118 #else
 119         atomic64_set(&tgt->acurs, atomic64_read(&src->acurs));
 120 #endif
 121 }
 122
 123 static inline void smc_curs_copy_net(union smc_cdc_cursor *tgt,
 124                                      union smc_cdc_cursor *src,
 125                                      struct smc_connection *conn)
 126 {
 127 #ifndef KERNEL_HAS_ATOMIC64
 128         unsigned long flags;
 129
 130         spin_lock_irqsave(&conn->acurs_lock, flags);
 131         tgt->acurs = src->acurs;
 132         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 133 #else
 134         atomic64_set(&tgt->acurs, atomic64_read(&src->acurs));
 135 #endif
 136 }
 137
 138 /* calculate cursor difference between old and new, where old <= new and
 139  * difference cannot exceed size
 140  */
 141 static inline int smc_curs_diff(unsigned int size,
 142                                 union smc_host_cursor *old,
 143                                 union smc_host_cursor *new)
 144 {
 145         if (old->wrap != new->wrap)
 146                 return max_t(int, 0,
 147                              ((size - old->count) + new->count));
 148
 149         return max_t(int, 0, (new->count - old->count));
 150 }
 151
 152 /* calculate cursor difference between old and new - returns negative
 153  * value in case old > new
 154  */
 155 static inline int smc_curs_comp(unsigned int size,
 156                                 union smc_host_cursor *old,
 157                                 union smc_host_cursor *new)
 158 {
 159         if (old->wrap > new->wrap ||
 160             (old->wrap == new->wrap && old->count > new->count))
 161                 return -smc_curs_diff(size, new, old);
 162         return smc_curs_diff(size, old, new);
 163 }
 164
 165 /* calculate cursor difference between old and new, where old <= new and
 166  * difference may exceed size
 167  */
 168 static inline int smc_curs_diff_large(unsigned int size,
 169                                       union smc_host_cursor *old,
 170                                       union smc_host_cursor *new)
 171 {
 172         if (old->wrap < new->wrap)
 173                 return min_t(int,
 174                              (size - old->count) + new->count +
 175                              (new->wrap - old->wrap - 1) * size,
 176                              size);
 177
 178         if (old->wrap > new->wrap) /* wrap has switched from 0xffff to 0x0000 */
 179                 return min_t(int,
 180                              (size - old->count) + new->count +
 181                              (new->wrap + 0xffff - old->wrap) * size,
 182                              size);
 183
 184         return max_t(int, 0, (new->count - old->count));
 185 }
 186
 187 static inline void smc_host_cursor_to_cdc(union smc_cdc_cursor *peer,
 188                                           union smc_host_cursor *local,
 189                                           union smc_host_cursor *save,
 190                                           struct smc_connection *conn)
 191 {
 192         smc_curs_copy(save, local, conn);
 193         peer->count = htonl(save->count);
 194         peer->wrap = htons(save->wrap);
 195         /* peer->reserved = htons(0); must be ensured by caller */
 196 }
 197
 198 static inline void smc_host_msg_to_cdc(struct smc_cdc_msg *peer,
 199                                        struct smc_connection *conn,
 200                                        union smc_host_cursor *save)
 201 {
 202         struct smc_host_cdc_msg *local = &conn->local_tx_ctrl;
 203
 204         peer->common.type = local->common.type;
 205         peer->len = local->len;
 206         peer->seqno = htons(local->seqno);
 207         peer->token = htonl(local->token);
 208         smc_host_cursor_to_cdc(&peer->prod, &local->prod, save, conn);
 209         smc_host_cursor_to_cdc(&peer->cons, &local->cons, save, conn);
 210         peer->prod_flags = local->prod_flags;
 211         peer->conn_state_flags = local->conn_state_flags;
 212 }
 213
 214 static inline void smc_cdc_cursor_to_host(union smc_host_cursor *local,
 215                                           union smc_cdc_cursor *peer,
 216                                           struct smc_connection *conn)
 217 {
 218         union smc_host_cursor temp, old;
 219         union smc_cdc_cursor net;
 220
 221         smc_curs_copy(&old, local, conn);
 222         smc_curs_copy_net(&net, peer, conn);
 223         temp.count = ntohl(net.count);
 224         temp.wrap = ntohs(net.wrap);
 225         if ((old.wrap > temp.wrap) && temp.wrap)
 226                 return;
 227         if ((old.wrap == temp.wrap) &&
 228             (old.count > temp.count))
 229                 return;
 230         smc_curs_copy(local, &temp, conn);
 231 }
 232
 233 static inline void smcr_cdc_msg_to_host(struct smc_host_cdc_msg *local,
 234                                         struct smc_cdc_msg *peer,
 235                                         struct smc_connection *conn)
 236 {
 237         local->common.type = peer->common.type;
 238         local->len = peer->len;
 239         local->seqno = ntohs(peer->seqno);
 240         local->token = ntohl(peer->token);
 241         smc_cdc_cursor_to_host(&local->prod, &peer->prod, conn);
 242         smc_cdc_cursor_to_host(&local->cons, &peer->cons, conn);
 243         local->prod_flags = peer->prod_flags;
 244         local->conn_state_flags = peer->conn_state_flags;
 245 }
 246
 247 static inline void smcd_cdc_msg_to_host(struct smc_host_cdc_msg *local,
 248                                         struct smcd_cdc_msg *peer)
 249 {
 250         local->prod.wrap = peer->prod_wrap;
 251         local->prod.count = peer->prod_count;
 252         local->cons.wrap = peer->cons_wrap;
 253         local->cons.count = peer->cons_count;
 254         local->prod_flags = peer->prod_flags;
 255         local->conn_state_flags = peer->conn_state_flags;
 256 }
 257
 258 static inline void smc_cdc_msg_to_host(struct smc_host_cdc_msg *local,
 259                                        struct smc_cdc_msg *peer,
 260                                        struct smc_connection *conn)
 261 {
 262         if (conn->lgr->is_smcd)
 263                 smcd_cdc_msg_to_host(local, (struct smcd_cdc_msg *)peer);
 264         else
 265                 smcr_cdc_msg_to_host(local, peer, conn);
 266 }
 267
 268 struct smc_cdc_tx_pend;
 269
 270 int smc_cdc_get_free_slot(struct smc_connection *conn,
 271                           struct smc_wr_buf **wr_buf,
 272                           struct smc_cdc_tx_pend **pend);
 273 void smc_cdc_tx_dismiss_slots(struct smc_connection *conn);
 274 int smc_cdc_msg_send(struct smc_connection *conn, struct smc_wr_buf *wr_buf,
 275                      struct smc_cdc_tx_pend *pend);
 276 int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn);
 277 int smcd_cdc_msg_send(struct smc_connection *conn);
 278 int smc_cdc_init(void) __init;
 279 void smcd_cdc_rx_init(struct smc_connection *conn);
 280
 281 #endif /* SMC_CDC_H */