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 static inline bool smc_cdc_rxed_any_close(struct smc_connection *conn)
  54 {
  55         return conn->local_rx_ctrl.conn_state_flags.peer_conn_abort ||
  56                conn->local_rx_ctrl.conn_state_flags.peer_conn_closed;
  57 }
  58
  59 static inline bool smc_cdc_rxed_any_close_or_senddone(
  60         struct smc_connection *conn)
  61 {
  62         return smc_cdc_rxed_any_close(conn) ||
  63                conn->local_rx_ctrl.conn_state_flags.peer_done_writing;
  64 }
  65
  66 static inline void smc_curs_add(int size, union smc_host_cursor *curs,
  67                                 int value)
  68 {
  69         curs->count += value;
  70         if (curs->count >= size) {
  71                 curs->wrap++;
  72                 curs->count -= size;
  73         }
  74 }
  75
  76 /* SMC cursors are 8 bytes long and require atomic reading and writing */
  77 static inline u64 smc_curs_read(union smc_host_cursor *curs,
  78                                 struct smc_connection *conn)
  79 {
  80 #ifndef KERNEL_HAS_ATOMIC64
  81         unsigned long flags;
  82         u64 ret;
  83
  84         spin_lock_irqsave(&conn->acurs_lock, flags);
  85         ret = curs->acurs;
  86         spin_unlock_irqrestore(&conn->acurs_lock, flags);
  87         return ret;
  88 #else
  89         return atomic64_read(&curs->acurs);
  90 #endif
  91 }
  92
  93 static inline u64 smc_curs_read_net(union smc_cdc_cursor *curs,
  94                                     struct smc_connection *conn)
  95 {
  96 #ifndef KERNEL_HAS_ATOMIC64
  97         unsigned long flags;
  98         u64 ret;
  99
 100         spin_lock_irqsave(&conn->acurs_lock, flags);
 101         ret = curs->acurs;
 102         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 103         return ret;
 104 #else
 105         return atomic64_read(&curs->acurs);
 106 #endif
 107 }
 108
 109 static inline void smc_curs_write(union smc_host_cursor *curs, u64 val,
 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         curs->acurs = val;
 117         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 118 #else
 119         atomic64_set(&curs->acurs, val);
 120 #endif
 121 }
 122
 123 static inline void smc_curs_write_net(union smc_cdc_cursor *curs, u64 val,
 124                                       struct smc_connection *conn)
 125 {
 126 #ifndef KERNEL_HAS_ATOMIC64
 127         unsigned long flags;
 128
 129         spin_lock_irqsave(&conn->acurs_lock, flags);
 130         curs->acurs = val;
 131         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 132 #else
 133         atomic64_set(&curs->acurs, val);
 134 #endif
 135 }
 136
 137 /* calculate cursor difference between old and new, where old <= new */
 138 static inline int smc_curs_diff(unsigned int size,
 139                                 union smc_host_cursor *old,
 140                                 union smc_host_cursor *new)
 141 {
 142         if (old->wrap != new->wrap)
 143                 return max_t(int, 0,
 144                              ((size - old->count) + new->count));
 145
 146         return max_t(int, 0, (new->count - old->count));
 147 }
 148
 149 /* calculate cursor difference between old and new - returns negative
 150  * value in case old > new
 151  */
 152 static inline int smc_curs_comp(unsigned int size,
 153                                 union smc_host_cursor *old,
 154                                 union smc_host_cursor *new)
 155 {
 156         if (old->wrap > new->wrap ||
 157             (old->wrap == new->wrap && old->count > new->count))
 158                 return -smc_curs_diff(size, new, old);
 159         return smc_curs_diff(size, old, new);
 160 }
 161
 162 static inline void smc_host_cursor_to_cdc(union smc_cdc_cursor *peer,
 163                                           union smc_host_cursor *local,
 164                                           struct smc_connection *conn)
 165 {
 166         union smc_host_cursor temp;
 167
 168         smc_curs_write(&temp, smc_curs_read(local, conn), conn);
 169         peer->count = htonl(temp.count);
 170         peer->wrap = htons(temp.wrap);
 171         /* peer->reserved = htons(0); must be ensured by caller */
 172 }
 173
 174 static inline void smc_host_msg_to_cdc(struct smc_cdc_msg *peer,
 175                                        struct smc_host_cdc_msg *local,
 176                                        struct smc_connection *conn)
 177 {
 178         peer->common.type = local->common.type;
 179         peer->len = local->len;
 180         peer->seqno = htons(local->seqno);
 181         peer->token = htonl(local->token);
 182         smc_host_cursor_to_cdc(&peer->prod, &local->prod, conn);
 183         smc_host_cursor_to_cdc(&peer->cons, &local->cons, conn);
 184         peer->prod_flags = local->prod_flags;
 185         peer->conn_state_flags = local->conn_state_flags;
 186 }
 187
 188 static inline void smc_cdc_cursor_to_host(union smc_host_cursor *local,
 189                                           union smc_cdc_cursor *peer,
 190                                           struct smc_connection *conn)
 191 {
 192         union smc_host_cursor temp, old;
 193         union smc_cdc_cursor net;
 194
 195         smc_curs_write(&old, smc_curs_read(local, conn), conn);
 196         smc_curs_write_net(&net, smc_curs_read_net(peer, conn), conn);
 197         temp.count = ntohl(net.count);
 198         temp.wrap = ntohs(net.wrap);
 199         if ((old.wrap > temp.wrap) && temp.wrap)
 200                 return;
 201         if ((old.wrap == temp.wrap) &&
 202             (old.count > temp.count))
 203                 return;
 204         smc_curs_write(local, smc_curs_read(&temp, conn), conn);
 205 }
 206
 207 static inline void smc_cdc_msg_to_host(struct smc_host_cdc_msg *local,
 208                                        struct smc_cdc_msg *peer,
 209                                        struct smc_connection *conn)
 210 {
 211         local->common.type = peer->common.type;
 212         local->len = peer->len;
 213         local->seqno = ntohs(peer->seqno);
 214         local->token = ntohl(peer->token);
 215         smc_cdc_cursor_to_host(&local->prod, &peer->prod, conn);
 216         smc_cdc_cursor_to_host(&local->cons, &peer->cons, conn);
 217         local->prod_flags = peer->prod_flags;
 218         local->conn_state_flags = peer->conn_state_flags;
 219 }
 220
 221 struct smc_cdc_tx_pend;
 222
 223 int smc_cdc_get_free_slot(struct smc_connection *conn,
 224                           struct smc_wr_buf **wr_buf,
 225                           struct smc_cdc_tx_pend **pend);
 226 void smc_cdc_tx_dismiss_slots(struct smc_connection *conn);
 227 int smc_cdc_msg_send(struct smc_connection *conn, struct smc_wr_buf *wr_buf,
 228                      struct smc_cdc_tx_pend *pend);
 229 int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn);
 230 int smc_cdc_init(void) __init;
 231
 232 #endif /* SMC_CDC_H */