usr/src/uts/common/io/ib/clients/rdsv3/ib_ring.c

   1 /*
   2  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
   3  */
   4
   5 /*
   6  * This file contains code imported from the OFED rds source file ib_ring.c
   7  * Oracle elects to have and use the contents of ib_ring.c under and governed
   8  * by the OpenIB.org BSD license (see below for full license text). However,
   9  * the following notice accompanied the original version of this file:
  10  */
  11
  12 /*
  13  * Copyright (c) 2006 Oracle.  All rights reserved.
  14  *
  15  * This software is available to you under a choice of one of two
  16  * licenses.  You may choose to be licensed under the terms of the GNU
  17  * General Public License (GPL) Version 2, available from the file
  18  * COPYING in the main directory of this source tree, or the
  19  * OpenIB.org BSD license below:
  20  *
  21  *     Redistribution and use in source and binary forms, with or
  22  *     without modification, are permitted provided that the following
  23  *     conditions are met:
  24  *
  25  *      - Redistributions of source code must retain the above
  26  *        copyright notice, this list of conditions and the following
  27  *        disclaimer.
  28  *
  29  *      - Redistributions in binary form must reproduce the above
  30  *        copyright notice, this list of conditions and the following
  31  *        disclaimer in the documentation and/or other materials
  32  *        provided with the distribution.
  33  *
  34  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  35  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  36  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  37  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  38  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  39  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  40  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  41  * SOFTWARE.
  42  *
  43  */
  44 #include <sys/rds.h>
  45
  46 #include <sys/ib/clients/rdsv3/rdsv3.h>
  47 #include <sys/ib/clients/rdsv3/ib.h>
  48 #include <sys/ib/clients/rdsv3/rdsv3_debug.h>
  49
  50 /*
  51  * Locking for IB rings.
  52  * We assume that allocation is always protected by a mutex
  53  * in the caller (this is a valid assumption for the current
  54  * implementation).
  55  *
  56  * Freeing always happens in an interrupt, and hence only
  57  * races with allocations, but not with other free()s.
  58  *
  59  * The interaction between allocation and freeing is that
  60  * the alloc code has to determine the number of free entries.
  61  * To this end, we maintain two counters; an allocation counter
  62  * and a free counter. Both are allowed to run freely, and wrap
  63  * around.
  64  * The number of used entries is always (alloc_ctr - free_ctr) % NR.
  65  *
  66  * The current implementation makes free_ctr atomic. When the
  67  * caller finds an allocation fails, it should set an "alloc fail"
  68  * bit and retry the allocation. The "alloc fail" bit essentially tells
  69  * the CQ completion handlers to wake it up after freeing some
  70  * more entries.
  71  */
  72
  73 void
  74 rdsv3_ib_ring_init(struct rdsv3_ib_work_ring *ring, uint32_t nr)
  75 {
  76         (void) memset(ring, 0, sizeof (*ring));
  77         ring->w_nr = nr;
  78         RDSV3_DPRINTF5("rdsv3_ib_ring_init", "ring %p nr %u", ring, ring->w_nr);
  79 }
  80
  81 static inline uint32_t
  82 __rdsv3_ib_ring_used(struct rdsv3_ib_work_ring *ring)
  83 {
  84         uint32_t diff;
  85
  86         /* This assumes that atomic_t has at least as many bits as uint32_t */
  87         diff = ring->w_alloc_ctr - (uint32_t)atomic_get(&ring->w_free_ctr);
  88         ASSERT(diff <= ring->w_nr);
  89
  90         return (diff);
  91 }
  92
  93 void
  94 rdsv3_ib_ring_resize(struct rdsv3_ib_work_ring *ring, uint32_t nr)
  95 {
  96         /*
  97          * We only ever get called from the connection setup code,
  98          * prior to creating the QP.
  99          */
 100         ASSERT(!__rdsv3_ib_ring_used(ring));
 101         ring->w_nr = nr;
 102 }
 103
 104 static int
 105 __rdsv3_ib_ring_empty(struct rdsv3_ib_work_ring *ring)
 106 {
 107         return (__rdsv3_ib_ring_used(ring) == 0);
 108 }
 109
 110 uint32_t
 111 rdsv3_ib_ring_alloc(struct rdsv3_ib_work_ring *ring, uint32_t val,
 112     uint32_t *pos)
 113 {
 114         uint32_t ret = 0, avail;
 115
 116         avail = ring->w_nr - __rdsv3_ib_ring_used(ring);
 117
 118         RDSV3_DPRINTF5("rdsv3_ib_ring_alloc",
 119             "ring %p val %u next %u free %u", ring, val,
 120             ring->w_alloc_ptr, avail);
 121
 122         if (val && avail) {
 123                 ret = min(val, avail);
 124                 *pos = ring->w_alloc_ptr;
 125
 126                 ring->w_alloc_ptr = (ring->w_alloc_ptr + ret) % ring->w_nr;
 127                 ring->w_alloc_ctr += ret;
 128         }
 129
 130         return (ret);
 131 }
 132
 133 void
 134 rdsv3_ib_ring_free(struct rdsv3_ib_work_ring *ring, uint32_t val)
 135 {
 136         ring->w_free_ptr = (ring->w_free_ptr + val) % ring->w_nr;
 137         atomic_add_32(&ring->w_free_ctr, val);
 138
 139         if (__rdsv3_ib_ring_empty(ring))
 140                 rdsv3_wake_up(&ring->w_empty_wait);
 141 }
 142
 143 void
 144 rdsv3_ib_ring_unalloc(struct rdsv3_ib_work_ring *ring, uint32_t val)
 145 {
 146         ring->w_alloc_ptr = (ring->w_alloc_ptr - val) % ring->w_nr;
 147         ring->w_alloc_ctr -= val;
 148 }
 149
 150 int
 151 rdsv3_ib_ring_empty(struct rdsv3_ib_work_ring *ring)
 152 {
 153         return (__rdsv3_ib_ring_empty(ring));
 154 }
 155
 156 int
 157 rdsv3_ib_ring_low(struct rdsv3_ib_work_ring *ring)
 158 {
 159         return (__rdsv3_ib_ring_used(ring) <= (ring->w_nr >> 2));
 160 }
 161
 162 /*
 163  * returns the oldest alloced ring entry.  This will be the next one
 164  * freed.  This can't be called if there are none allocated.
 165  */
 166 uint32_t
 167 rdsv3_ib_ring_oldest(struct rdsv3_ib_work_ring *ring)
 168 {
 169         return (ring->w_free_ptr);
 170 }
 171
 172 /*
 173  * returns the number of completed work requests.
 174  */
 175
 176 uint32_t
 177 rdsv3_ib_ring_completed(struct rdsv3_ib_work_ring *ring,
 178     uint32_t wr_id, uint32_t oldest)
 179 {
 180         uint32_t ret;
 181
 182         if (oldest <= (unsigned long long)wr_id)
 183                 ret = (unsigned long long)wr_id - oldest + 1;
 184         else
 185                 ret = ring->w_nr - oldest + (unsigned long long)wr_id + 1;
 186
 187         RDSV3_DPRINTF5("rdsv3_ib_ring_completed",
 188             "ring %p ret %u wr_id %u oldest %u", ring, ret, wr_id, oldest);
 189         return (ret);
 190 }