Linux Audio

Check our new training course

Loading...
v3.5.6
  1/*
  2 * Copyright (c) 2006 Oracle.  All rights reserved.
  3 *
  4 * This software is available to you under a choice of one of two
  5 * licenses.  You may choose to be licensed under the terms of the GNU
  6 * General Public License (GPL) Version 2, available from the file
  7 * COPYING in the main directory of this source tree, or the
  8 * OpenIB.org BSD license below:
  9 *
 10 *     Redistribution and use in source and binary forms, with or
 11 *     without modification, are permitted provided that the following
 12 *     conditions are met:
 13 *
 14 *      - Redistributions of source code must retain the above
 15 *        copyright notice, this list of conditions and the following
 16 *        disclaimer.
 17 *
 18 *      - Redistributions in binary form must reproduce the above
 19 *        copyright notice, this list of conditions and the following
 20 *        disclaimer in the documentation and/or other materials
 21 *        provided with the distribution.
 22 *
 23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 30 * SOFTWARE.
 31 *
 32 */
 33#include <linux/kernel.h>
 34
 35#include "rds.h"
 36#include "ib.h"
 37
 38/*
 39 * Locking for IB rings.
 40 * We assume that allocation is always protected by a mutex
 41 * in the caller (this is a valid assumption for the current
 42 * implementation).
 43 *
 44 * Freeing always happens in an interrupt, and hence only
 45 * races with allocations, but not with other free()s.
 46 *
 47 * The interaction between allocation and freeing is that
 48 * the alloc code has to determine the number of free entries.
 49 * To this end, we maintain two counters; an allocation counter
 50 * and a free counter. Both are allowed to run freely, and wrap
 51 * around.
 52 * The number of used entries is always (alloc_ctr - free_ctr) % NR.
 53 *
 54 * The current implementation makes free_ctr atomic. When the
 55 * caller finds an allocation fails, it should set an "alloc fail"
 56 * bit and retry the allocation. The "alloc fail" bit essentially tells
 57 * the CQ completion handlers to wake it up after freeing some
 58 * more entries.
 59 */
 60
 61/*
 62 * This only happens on shutdown.
 63 */
 64DECLARE_WAIT_QUEUE_HEAD(rds_ib_ring_empty_wait);
 65
 66void rds_ib_ring_init(struct rds_ib_work_ring *ring, u32 nr)
 67{
 68	memset(ring, 0, sizeof(*ring));
 69	ring->w_nr = nr;
 70	rdsdebug("ring %p nr %u\n", ring, ring->w_nr);
 71}
 72
 73static inline u32 __rds_ib_ring_used(struct rds_ib_work_ring *ring)
 74{
 75	u32 diff;
 76
 77	/* This assumes that atomic_t has at least as many bits as u32 */
 78	diff = ring->w_alloc_ctr - (u32) atomic_read(&ring->w_free_ctr);
 79	BUG_ON(diff > ring->w_nr);
 80
 81	return diff;
 82}
 83
 84void rds_ib_ring_resize(struct rds_ib_work_ring *ring, u32 nr)
 85{
 86	/* We only ever get called from the connection setup code,
 87	 * prior to creating the QP. */
 88	BUG_ON(__rds_ib_ring_used(ring));
 89	ring->w_nr = nr;
 90}
 91
 92static int __rds_ib_ring_empty(struct rds_ib_work_ring *ring)
 93{
 94	return __rds_ib_ring_used(ring) == 0;
 95}
 96
 97u32 rds_ib_ring_alloc(struct rds_ib_work_ring *ring, u32 val, u32 *pos)
 98{
 99	u32 ret = 0, avail;
100
101	avail = ring->w_nr - __rds_ib_ring_used(ring);
102
103	rdsdebug("ring %p val %u next %u free %u\n", ring, val,
104		 ring->w_alloc_ptr, avail);
105
106	if (val && avail) {
107		ret = min(val, avail);
108		*pos = ring->w_alloc_ptr;
109
110		ring->w_alloc_ptr = (ring->w_alloc_ptr + ret) % ring->w_nr;
111		ring->w_alloc_ctr += ret;
112	}
113
114	return ret;
115}
116
117void rds_ib_ring_free(struct rds_ib_work_ring *ring, u32 val)
118{
119	ring->w_free_ptr = (ring->w_free_ptr + val) % ring->w_nr;
120	atomic_add(val, &ring->w_free_ctr);
121
122	if (__rds_ib_ring_empty(ring) &&
123	    waitqueue_active(&rds_ib_ring_empty_wait))
124		wake_up(&rds_ib_ring_empty_wait);
125}
126
127void rds_ib_ring_unalloc(struct rds_ib_work_ring *ring, u32 val)
128{
129	ring->w_alloc_ptr = (ring->w_alloc_ptr - val) % ring->w_nr;
130	ring->w_alloc_ctr -= val;
131}
132
133int rds_ib_ring_empty(struct rds_ib_work_ring *ring)
134{
135	return __rds_ib_ring_empty(ring);
136}
137
138int rds_ib_ring_low(struct rds_ib_work_ring *ring)
139{
140	return __rds_ib_ring_used(ring) <= (ring->w_nr >> 1);
141}
142
143/*
144 * returns the oldest alloced ring entry.  This will be the next one
145 * freed.  This can't be called if there are none allocated.
146 */
147u32 rds_ib_ring_oldest(struct rds_ib_work_ring *ring)
148{
149	return ring->w_free_ptr;
150}
151
152/*
153 * returns the number of completed work requests.
154 */
155
156u32 rds_ib_ring_completed(struct rds_ib_work_ring *ring, u32 wr_id, u32 oldest)
157{
158	u32 ret;
159
160	if (oldest <= (unsigned long long)wr_id)
161		ret = (unsigned long long)wr_id - oldest + 1;
162	else
163		ret = ring->w_nr - oldest + (unsigned long long)wr_id + 1;
164
165	rdsdebug("ring %p ret %u wr_id %u oldest %u\n", ring, ret,
166		 wr_id, oldest);
167	return ret;
168}
v4.17
  1/*
  2 * Copyright (c) 2006 Oracle.  All rights reserved.
  3 *
  4 * This software is available to you under a choice of one of two
  5 * licenses.  You may choose to be licensed under the terms of the GNU
  6 * General Public License (GPL) Version 2, available from the file
  7 * COPYING in the main directory of this source tree, or the
  8 * OpenIB.org BSD license below:
  9 *
 10 *     Redistribution and use in source and binary forms, with or
 11 *     without modification, are permitted provided that the following
 12 *     conditions are met:
 13 *
 14 *      - Redistributions of source code must retain the above
 15 *        copyright notice, this list of conditions and the following
 16 *        disclaimer.
 17 *
 18 *      - Redistributions in binary form must reproduce the above
 19 *        copyright notice, this list of conditions and the following
 20 *        disclaimer in the documentation and/or other materials
 21 *        provided with the distribution.
 22 *
 23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 30 * SOFTWARE.
 31 *
 32 */
 33#include <linux/kernel.h>
 34
 35#include "rds.h"
 36#include "ib.h"
 37
 38/*
 39 * Locking for IB rings.
 40 * We assume that allocation is always protected by a mutex
 41 * in the caller (this is a valid assumption for the current
 42 * implementation).
 43 *
 44 * Freeing always happens in an interrupt, and hence only
 45 * races with allocations, but not with other free()s.
 46 *
 47 * The interaction between allocation and freeing is that
 48 * the alloc code has to determine the number of free entries.
 49 * To this end, we maintain two counters; an allocation counter
 50 * and a free counter. Both are allowed to run freely, and wrap
 51 * around.
 52 * The number of used entries is always (alloc_ctr - free_ctr) % NR.
 53 *
 54 * The current implementation makes free_ctr atomic. When the
 55 * caller finds an allocation fails, it should set an "alloc fail"
 56 * bit and retry the allocation. The "alloc fail" bit essentially tells
 57 * the CQ completion handlers to wake it up after freeing some
 58 * more entries.
 59 */
 60
 61/*
 62 * This only happens on shutdown.
 63 */
 64DECLARE_WAIT_QUEUE_HEAD(rds_ib_ring_empty_wait);
 65
 66void rds_ib_ring_init(struct rds_ib_work_ring *ring, u32 nr)
 67{
 68	memset(ring, 0, sizeof(*ring));
 69	ring->w_nr = nr;
 70	rdsdebug("ring %p nr %u\n", ring, ring->w_nr);
 71}
 72
 73static inline u32 __rds_ib_ring_used(struct rds_ib_work_ring *ring)
 74{
 75	u32 diff;
 76
 77	/* This assumes that atomic_t has at least as many bits as u32 */
 78	diff = ring->w_alloc_ctr - (u32) atomic_read(&ring->w_free_ctr);
 79	BUG_ON(diff > ring->w_nr);
 80
 81	return diff;
 82}
 83
 84void rds_ib_ring_resize(struct rds_ib_work_ring *ring, u32 nr)
 85{
 86	/* We only ever get called from the connection setup code,
 87	 * prior to creating the QP. */
 88	BUG_ON(__rds_ib_ring_used(ring));
 89	ring->w_nr = nr;
 90}
 91
 92static int __rds_ib_ring_empty(struct rds_ib_work_ring *ring)
 93{
 94	return __rds_ib_ring_used(ring) == 0;
 95}
 96
 97u32 rds_ib_ring_alloc(struct rds_ib_work_ring *ring, u32 val, u32 *pos)
 98{
 99	u32 ret = 0, avail;
100
101	avail = ring->w_nr - __rds_ib_ring_used(ring);
102
103	rdsdebug("ring %p val %u next %u free %u\n", ring, val,
104		 ring->w_alloc_ptr, avail);
105
106	if (val && avail) {
107		ret = min(val, avail);
108		*pos = ring->w_alloc_ptr;
109
110		ring->w_alloc_ptr = (ring->w_alloc_ptr + ret) % ring->w_nr;
111		ring->w_alloc_ctr += ret;
112	}
113
114	return ret;
115}
116
117void rds_ib_ring_free(struct rds_ib_work_ring *ring, u32 val)
118{
119	ring->w_free_ptr = (ring->w_free_ptr + val) % ring->w_nr;
120	atomic_add(val, &ring->w_free_ctr);
121
122	if (__rds_ib_ring_empty(ring) &&
123	    waitqueue_active(&rds_ib_ring_empty_wait))
124		wake_up(&rds_ib_ring_empty_wait);
125}
126
127void rds_ib_ring_unalloc(struct rds_ib_work_ring *ring, u32 val)
128{
129	ring->w_alloc_ptr = (ring->w_alloc_ptr - val) % ring->w_nr;
130	ring->w_alloc_ctr -= val;
131}
132
133int rds_ib_ring_empty(struct rds_ib_work_ring *ring)
134{
135	return __rds_ib_ring_empty(ring);
136}
137
138int rds_ib_ring_low(struct rds_ib_work_ring *ring)
139{
140	return __rds_ib_ring_used(ring) <= (ring->w_nr >> 1);
141}
142
143/*
144 * returns the oldest alloced ring entry.  This will be the next one
145 * freed.  This can't be called if there are none allocated.
146 */
147u32 rds_ib_ring_oldest(struct rds_ib_work_ring *ring)
148{
149	return ring->w_free_ptr;
150}
151
152/*
153 * returns the number of completed work requests.
154 */
155
156u32 rds_ib_ring_completed(struct rds_ib_work_ring *ring, u32 wr_id, u32 oldest)
157{
158	u32 ret;
159
160	if (oldest <= (unsigned long long)wr_id)
161		ret = (unsigned long long)wr_id - oldest + 1;
162	else
163		ret = ring->w_nr - oldest + (unsigned long long)wr_id + 1;
164
165	rdsdebug("ring %p ret %u wr_id %u oldest %u\n", ring, ret,
166		 wr_id, oldest);
167	return ret;
168}