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 } __aligned(8);
  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 static inline void smc_host_cursor_to_cdc(union smc_cdc_cursor *peer,
 150                                           union smc_host_cursor *local,
 151                                           struct smc_connection *conn)
 152 {
 153         union smc_host_cursor temp;
 154
 155         smc_curs_write(&temp, smc_curs_read(local, conn), conn);
 156         peer->count = htonl(temp.count);
 157         peer->wrap = htons(temp.wrap);
 158         /* peer->reserved = htons(0); must be ensured by caller */
 159 }
 160
 161 static inline void smc_host_msg_to_cdc(struct smc_cdc_msg *peer,
 162                                        struct smc_host_cdc_msg *local,
 163                                        struct smc_connection *conn)
 164 {
 165         peer->common.type = local->common.type;
 166         peer->len = local->len;
 167         peer->seqno = htons(local->seqno);
 168         peer->token = htonl(local->token);
 169         smc_host_cursor_to_cdc(&peer->prod, &local->prod, conn);
 170         smc_host_cursor_to_cdc(&peer->cons, &local->cons, conn);
 171         peer->prod_flags = local->prod_flags;
 172         peer->conn_state_flags = local->conn_state_flags;
 173 }
 174
 175 static inline void smc_cdc_cursor_to_host(union smc_host_cursor *local,
 176                                           union smc_cdc_cursor *peer,
 177                                           struct smc_connection *conn)
 178 {
 179         union smc_host_cursor temp, old;
 180         union smc_cdc_cursor net;
 181
 182         smc_curs_write(&old, smc_curs_read(local, conn), conn);
 183         smc_curs_write_net(&net, smc_curs_read_net(peer, conn), conn);
 184         temp.count = ntohl(net.count);
 185         temp.wrap = ntohs(net.wrap);
 186         if ((old.wrap > temp.wrap) && temp.wrap)
 187                 return;
 188         if ((old.wrap == temp.wrap) &&
 189             (old.count > temp.count))
 190                 return;
 191         smc_curs_write(local, smc_curs_read(&temp, conn), conn);
 192 }
 193
 194 static inline void smc_cdc_msg_to_host(struct smc_host_cdc_msg *local,
 195                                        struct smc_cdc_msg *peer,
 196                                        struct smc_connection *conn)
 197 {
 198         local->common.type = peer->common.type;
 199         local->len = peer->len;
 200         local->seqno = ntohs(peer->seqno);
 201         local->token = ntohl(peer->token);
 202         smc_cdc_cursor_to_host(&local->prod, &peer->prod, conn);
 203         smc_cdc_cursor_to_host(&local->cons, &peer->cons, conn);
 204         local->prod_flags = peer->prod_flags;
 205         local->conn_state_flags = peer->conn_state_flags;
 206 }
 207
 208 struct smc_cdc_tx_pend;
 209
 210 int smc_cdc_get_free_slot(struct smc_connection *conn,
 211                           struct smc_wr_buf **wr_buf,
 212                           struct smc_cdc_tx_pend **pend);
 213 void smc_cdc_tx_dismiss_slots(struct smc_connection *conn);
 214 int smc_cdc_msg_send(struct smc_connection *conn, struct smc_wr_buf *wr_buf,
 215                      struct smc_cdc_tx_pend *pend);
 216 int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn);
 217 bool smc_cdc_tx_has_pending(struct smc_connection *conn);
 218 int smc_cdc_init(void) __init;
 219
 220 #endif /* SMC_CDC_H */