16e76cdd6e3cfaac7d91c3b0644ee1bc6cf52347agiri * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
16e76cdd6e3cfaac7d91c3b0644ee1bc6cf52347agiri * This file contains code imported from the OFED rds source file ib_ring.c
16e76cdd6e3cfaac7d91c3b0644ee1bc6cf52347agiri * Oracle elects to have and use the contents of ib_ring.c under and governed
16e76cdd6e3cfaac7d91c3b0644ee1bc6cf52347agiri * by the OpenIB.org BSD license (see below for full license text). However,
16e76cdd6e3cfaac7d91c3b0644ee1bc6cf52347agiri * the following notice accompanied the original version of this file:
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * Copyright (c) 2006 Oracle. All rights reserved.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * This software is available to you under a choice of one of two
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * licenses. You may choose to be licensed under the terms of the GNU
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * General Public License (GPL) Version 2, available from the file
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * COPYING in the main directory of this source tree, or the
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * OpenIB.org BSD license below:
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * Redistribution and use in source and binary forms, with or
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * without modification, are permitted provided that the following
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * conditions are met:
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * - Redistributions of source code must retain the above
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * copyright notice, this list of conditions and the following
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * disclaimer.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * - Redistributions in binary form must reproduce the above
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * copyright notice, this list of conditions and the following
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * disclaimer in the documentation and/or other materials
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * provided with the distribution.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * SOFTWARE.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * Locking for IB rings.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * We assume that allocation is always protected by a mutex
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * in the caller (this is a valid assumption for the current
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * implementation).
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * Freeing always happens in an interrupt, and hence only
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * races with allocations, but not with other free()s.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * The interaction between allocation and freeing is that
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * the alloc code has to determine the number of free entries.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * To this end, we maintain two counters; an allocation counter
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * and a free counter. Both are allowed to run freely, and wrap
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * The number of used entries is always (alloc_ctr - free_ctr) % NR.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * The current implementation makes free_ctr atomic. When the
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * caller finds an allocation fails, it should set an "alloc fail"
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * bit and retry the allocation. The "alloc fail" bit essentially tells
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * the CQ completion handlers to wake it up after freeing some
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * more entries.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_init(struct rdsv3_ib_work_ring *ring, uint32_t nr)
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota RDSV3_DPRINTF5("rdsv3_ib_ring_init", "ring %p nr %u", ring, ring->w_nr);
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otastatic inline uint32_t
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota__rdsv3_ib_ring_used(struct rdsv3_ib_work_ring *ring)
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota /* This assumes that atomic_t has at least as many bits as uint32_t */
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota diff = ring->w_alloc_ctr - (uint32_t)atomic_get(&ring->w_free_ctr);
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_resize(struct rdsv3_ib_work_ring *ring, uint32_t nr)
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * We only ever get called from the connection setup code,
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * prior to creating the QP.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota__rdsv3_ib_ring_empty(struct rdsv3_ib_work_ring *ring)
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_alloc(struct rdsv3_ib_work_ring *ring, uint32_t val,
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota ring->w_alloc_ptr = (ring->w_alloc_ptr + ret) % ring->w_nr;
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_free(struct rdsv3_ib_work_ring *ring, uint32_t val)
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota ring->w_free_ptr = (ring->w_free_ptr + val) % ring->w_nr;
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_unalloc(struct rdsv3_ib_work_ring *ring, uint32_t val)
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota ring->w_alloc_ptr = (ring->w_alloc_ptr - val) % ring->w_nr;
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_empty(struct rdsv3_ib_work_ring *ring)
cadbfdc3bdb156e92d7a88978bc98ea87f6e037fEiji Ota return (__rdsv3_ib_ring_used(ring) <= (ring->w_nr >> 2));
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * returns the oldest alloced ring entry. This will be the next one
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * freed. This can't be called if there are none allocated.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_oldest(struct rdsv3_ib_work_ring *ring)
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota * returns the number of completed work requests.
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Otardsv3_ib_ring_completed(struct rdsv3_ib_work_ring *ring,
c0dd49bdd68c0d758a67d56f07826f3b45cfc664Eiji Ota ret = ring->w_nr - oldest + (unsigned long long)wr_id + 1;