net/smc/smc_cdc.h

   1 /*
   2  * Shared Memory Communications over RDMA (SMC-R) and RoCE
   3  *
   4  * Connection Data Control (CDC)
   5  *
   6  * Copyright IBM Corp. 2016
   7  *
   8  * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
   9  */
  10
  11 #ifndef SMC_CDC_H
  12 #define SMC_CDC_H
  13
  14 #include <linux/kernel.h> /* max_t */
  15 #include <linux/atomic.h>
  16 #include <linux/in.h>
  17 #include <linux/compiler.h>
  18
  19 #include "smc.h"
  20 #include "smc_core.h"
  21 #include "smc_wr.h"
  22
  23 #define SMC_CDC_MSG_TYPE                0xFE
  24
  25 /* in network byte order */
  26 union smc_cdc_cursor {          /* SMC cursor */
  27         struct {
  28                 __be16  reserved;
  29                 __be16  wrap;
  30                 __be32  count;
  31         };
  32 #ifdef KERNEL_HAS_ATOMIC64
  33         atomic64_t      acurs;          /* for atomic processing */
  34 #else
  35         u64             acurs;          /* for atomic processing */
  36 #endif
  37 } __aligned(8);
  38
  39 /* in network byte order */
  40 struct smc_cdc_msg {
  41         struct smc_wr_rx_hdr            common; /* .type = 0xFE */
  42         u8                              len;    /* 44 */
  43         __be16                          seqno;
  44         __be32                          token;
  45         union smc_cdc_cursor            prod;
  46         union smc_cdc_cursor            cons;   /* piggy backed "ack" */
  47         struct smc_cdc_producer_flags   prod_flags;
  48         struct smc_cdc_conn_state_flags conn_state_flags;
  49         u8                              reserved[18];
  50 } __aligned(8);
  51
  52 static inline bool smc_cdc_rxed_any_close(struct smc_connection *conn)
  53 {
  54         return conn->local_rx_ctrl.conn_state_flags.peer_conn_abort ||
  55                conn->local_rx_ctrl.conn_state_flags.peer_conn_closed;
  56 }
  57
  58 static inline bool smc_cdc_rxed_any_close_or_senddone(
  59         struct smc_connection *conn)
  60 {
  61         return smc_cdc_rxed_any_close(conn) ||
  62                conn->local_rx_ctrl.conn_state_flags.peer_done_writing;
  63 }
  64
  65 static inline void smc_curs_add(int size, union smc_host_cursor *curs,
  66                                 int value)
  67 {
  68         curs->count += value;
  69         if (curs->count >= size) {
  70                 curs->wrap++;
  71                 curs->count -= size;
  72         }
  73 }
  74
  75 /* SMC cursors are 8 bytes long and require atomic reading and writing */
  76 static inline u64 smc_curs_read(union smc_host_cursor *curs,
  77                                 struct smc_connection *conn)
  78 {
  79 #ifndef KERNEL_HAS_ATOMIC64
  80         unsigned long flags;
  81         u64 ret;
  82
  83         spin_lock_irqsave(&conn->acurs_lock, flags);
  84         ret = curs->acurs;
  85         spin_unlock_irqrestore(&conn->acurs_lock, flags);
  86         return ret;
  87 #else
  88         return atomic64_read(&curs->acurs);
  89 #endif
  90 }
  91
  92 static inline u64 smc_curs_read_net(union smc_cdc_cursor *curs,
  93                                     struct smc_connection *conn)
  94 {
  95 #ifndef KERNEL_HAS_ATOMIC64
  96         unsigned long flags;
  97         u64 ret;
  98
  99         spin_lock_irqsave(&conn->acurs_lock, flags);
 100         ret = curs->acurs;
 101         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 102         return ret;
 103 #else
 104         return atomic64_read(&curs->acurs);
 105 #endif
 106 }
 107
 108 static inline void smc_curs_write(union smc_host_cursor *curs, u64 val,
 109                                   struct smc_connection *conn)
 110 {
 111 #ifndef KERNEL_HAS_ATOMIC64
 112         unsigned long flags;
 113
 114         spin_lock_irqsave(&conn->acurs_lock, flags);
 115         curs->acurs = val;
 116         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 117 #else
 118         atomic64_set(&curs->acurs, val);
 119 #endif
 120 }
 121
 122 static inline void smc_curs_write_net(union smc_cdc_cursor *curs, u64 val,
 123                                       struct smc_connection *conn)
 124 {
 125 #ifndef KERNEL_HAS_ATOMIC64
 126         unsigned long flags;
 127
 128         spin_lock_irqsave(&conn->acurs_lock, flags);
 129         curs->acurs = val;
 130         spin_unlock_irqrestore(&conn->acurs_lock, flags);
 131 #else
 132         atomic64_set(&curs->acurs, val);
 133 #endif
 134 }
 135
 136 /* calculate cursor difference between old and new, where old <= new */
 137 static inline int smc_curs_diff(unsigned int size,
 138                                 union smc_host_cursor *old,
 139                                 union smc_host_cursor *new)
 140 {
 141         if (old->wrap != new->wrap)
 142                 return max_t(int, 0,
 143                              ((size - old->count) + new->count));
 144
 145         return max_t(int, 0, (new->count - old->count));
 146 }
 147
 148 static inline void smc_host_cursor_to_cdc(union smc_cdc_cursor *peer,
 149                                           union smc_host_cursor *local,
 150                                           struct smc_connection *conn)
 151 {
 152         union smc_host_cursor temp;
 153
 154         smc_curs_write(&temp, smc_curs_read(local, conn), conn);
 155         peer->count = htonl(temp.count);
 156         peer->wrap = htons(temp.wrap);
 157         /* peer->reserved = htons(0); must be ensured by caller */
 158 }
 159
 160 static inline void smc_host_msg_to_cdc(struct smc_cdc_msg *peer,
 161                                        struct smc_host_cdc_msg *local,
 162                                        struct smc_connection *conn)
 163 {
 164         peer->common.type = local->common.type;
 165         peer->len = local->len;
 166         peer->seqno = htons(local->seqno);
 167         peer->token = htonl(local->token);
 168         smc_host_cursor_to_cdc(&peer->prod, &local->prod, conn);
 169         smc_host_cursor_to_cdc(&peer->cons, &local->cons, conn);
 170         peer->prod_flags = local->prod_flags;
 171         peer->conn_state_flags = local->conn_state_flags;
 172 }
 173
 174 static inline void smc_cdc_cursor_to_host(union smc_host_cursor *local,
 175                                           union smc_cdc_cursor *peer,
 176                                           struct smc_connection *conn)
 177 {
 178         union smc_host_cursor temp, old;
 179         union smc_cdc_cursor net;
 180
 181         smc_curs_write(&old, smc_curs_read(local, conn), conn);
 182         smc_curs_write_net(&net, smc_curs_read_net(peer, conn), conn);
 183         temp.count = ntohl(net.count);
 184         temp.wrap = ntohs(net.wrap);
 185         if ((old.wrap > temp.wrap) && temp.wrap)
 186                 return;
 187         if ((old.wrap == temp.wrap) &&
 188             (old.count > temp.count))
 189                 return;
 190         smc_curs_write(local, smc_curs_read(&temp, conn), conn);
 191 }
 192
 193 static inline void smc_cdc_msg_to_host(struct smc_host_cdc_msg *local,
 194                                        struct smc_cdc_msg *peer,
 195                                        struct smc_connection *conn)
 196 {
 197         local->common.type = peer->common.type;
 198         local->len = peer->len;
 199         local->seqno = ntohs(peer->seqno);
 200         local->token = ntohl(peer->token);
 201         smc_cdc_cursor_to_host(&local->prod, &peer->prod, conn);
 202         smc_cdc_cursor_to_host(&local->cons, &peer->cons, conn);
 203         local->prod_flags = peer->prod_flags;
 204         local->conn_state_flags = peer->conn_state_flags;
 205 }
 206
 207 struct smc_cdc_tx_pend;
 208
 209 int smc_cdc_get_free_slot(struct smc_link *link, struct smc_wr_buf **wr_buf,
 210                           struct smc_cdc_tx_pend **pend);
 211 void smc_cdc_tx_dismiss_slots(struct smc_connection *conn);
 212 int smc_cdc_msg_send(struct smc_connection *conn, struct smc_wr_buf *wr_buf,
 213                      struct smc_cdc_tx_pend *pend);
 214 int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn);
 215 bool smc_cdc_tx_has_pending(struct smc_connection *conn);
 216 int smc_cdc_init(void) __init;
 217
 218 #endif /* SMC_CDC_H */