ib_ring.c revision 16e76cdd6e3cfaac7d91c3b0644ee1bc6cf52347
/*
*/
/*
* This file contains code imported from the OFED rds source file ib_ring.c
* Oracle elects to have and use the contents of ib_ring.c under and governed
* by the OpenIB.org BSD license (see below for full license text). However,
* the following notice accompanied the original version of this file:
*/
/*
* Copyright (c) 2006 Oracle. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
/*
* Locking for IB rings.
* We assume that allocation is always protected by a mutex
* in the caller (this is a valid assumption for the current
* implementation).
*
* Freeing always happens in an interrupt, and hence only
* races with allocations, but not with other free()s.
*
* The interaction between allocation and freeing is that
* the alloc code has to determine the number of free entries.
* To this end, we maintain two counters; an allocation counter
* and a free counter. Both are allowed to run freely, and wrap
* around.
* The number of used entries is always (alloc_ctr - free_ctr) % NR.
*
* The current implementation makes free_ctr atomic. When the
* caller finds an allocation fails, it should set an "alloc fail"
* bit and retry the allocation. The "alloc fail" bit essentially tells
* the CQ completion handlers to wake it up after freeing some
* more entries.
*/
void
{
}
static inline uint32_t
{
/* This assumes that atomic_t has at least as many bits as uint32_t */
return (diff);
}
void
{
/*
* We only ever get called from the connection setup code,
* prior to creating the QP.
*/
}
static int
{
return (__rdsv3_ib_ring_used(ring) == 0);
}
{
RDSV3_DPRINTF5("rdsv3_ib_ring_alloc",
}
return (ret);
}
void
{
if (__rdsv3_ib_ring_empty(ring))
}
void
{
}
int
{
return (__rdsv3_ib_ring_empty(ring));
}
int
{
}
/*
* returns the oldest alloced ring entry. This will be the next one
* freed. This can't be called if there are none allocated.
*/
{
return (ring->w_free_ptr);
}
/*
* returns the number of completed work requests.
*/
{
else
RDSV3_DPRINTF5("rdsv3_ib_ring_completed",
return (ret);
}