169 lines
4.8 KiB
C
Executable File
169 lines
4.8 KiB
C
Executable 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
|
|
* disclaimer in the documentation and/or other materials
|
|
* 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.
|
|
*
|
|
*/
|
|
#include <linux/kernel.h>
|
|
|
|
#include "rds.h"
|
|
#include "ib.h"
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
/*
|
|
* This only happens on shutdown.
|
|
*/
|
|
DECLARE_WAIT_QUEUE_HEAD(rds_ib_ring_empty_wait);
|
|
|
|
void rds_ib_ring_init(struct rds_ib_work_ring *ring, u32 nr)
|
|
{
|
|
memset(ring, 0, sizeof(*ring));
|
|
ring->w_nr = nr;
|
|
rdsdebug("ring %p nr %u\n", ring, ring->w_nr);
|
|
}
|
|
|
|
static inline u32 __rds_ib_ring_used(struct rds_ib_work_ring *ring)
|
|
{
|
|
u32 diff;
|
|
|
|
/* This assumes that atomic_t has at least as many bits as u32 */
|
|
diff = ring->w_alloc_ctr - (u32) atomic_read(&ring->w_free_ctr);
|
|
BUG_ON(diff > ring->w_nr);
|
|
|
|
return diff;
|
|
}
|
|
|
|
void rds_ib_ring_resize(struct rds_ib_work_ring *ring, u32 nr)
|
|
{
|
|
/* We only ever get called from the connection setup code,
|
|
* prior to creating the QP. */
|
|
BUG_ON(__rds_ib_ring_used(ring));
|
|
ring->w_nr = nr;
|
|
}
|
|
|
|
static int __rds_ib_ring_empty(struct rds_ib_work_ring *ring)
|
|
{
|
|
return __rds_ib_ring_used(ring) == 0;
|
|
}
|
|
|
|
u32 rds_ib_ring_alloc(struct rds_ib_work_ring *ring, u32 val, u32 *pos)
|
|
{
|
|
u32 ret = 0, avail;
|
|
|
|
avail = ring->w_nr - __rds_ib_ring_used(ring);
|
|
|
|
rdsdebug("ring %p val %u next %u free %u\n", ring, val,
|
|
ring->w_alloc_ptr, avail);
|
|
|
|
if (val && avail) {
|
|
ret = min(val, avail);
|
|
*pos = ring->w_alloc_ptr;
|
|
|
|
ring->w_alloc_ptr = (ring->w_alloc_ptr + ret) % ring->w_nr;
|
|
ring->w_alloc_ctr += ret;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
void rds_ib_ring_free(struct rds_ib_work_ring *ring, u32 val)
|
|
{
|
|
ring->w_free_ptr = (ring->w_free_ptr + val) % ring->w_nr;
|
|
atomic_add(val, &ring->w_free_ctr);
|
|
|
|
if (__rds_ib_ring_empty(ring) &&
|
|
waitqueue_active(&rds_ib_ring_empty_wait))
|
|
wake_up(&rds_ib_ring_empty_wait);
|
|
}
|
|
|
|
void rds_ib_ring_unalloc(struct rds_ib_work_ring *ring, u32 val)
|
|
{
|
|
ring->w_alloc_ptr = (ring->w_alloc_ptr - val) % ring->w_nr;
|
|
ring->w_alloc_ctr -= val;
|
|
}
|
|
|
|
int rds_ib_ring_empty(struct rds_ib_work_ring *ring)
|
|
{
|
|
return __rds_ib_ring_empty(ring);
|
|
}
|
|
|
|
int rds_ib_ring_low(struct rds_ib_work_ring *ring)
|
|
{
|
|
return __rds_ib_ring_used(ring) <= (ring->w_nr >> 1);
|
|
}
|
|
|
|
/*
|
|
* returns the oldest alloced ring entry. This will be the next one
|
|
* freed. This can't be called if there are none allocated.
|
|
*/
|
|
u32 rds_ib_ring_oldest(struct rds_ib_work_ring *ring)
|
|
{
|
|
return ring->w_free_ptr;
|
|
}
|
|
|
|
/*
|
|
* returns the number of completed work requests.
|
|
*/
|
|
|
|
u32 rds_ib_ring_completed(struct rds_ib_work_ring *ring, u32 wr_id, u32 oldest)
|
|
{
|
|
u32 ret;
|
|
|
|
if (oldest <= (unsigned long long)wr_id)
|
|
ret = (unsigned long long)wr_id - oldest + 1;
|
|
else
|
|
ret = ring->w_nr - oldest + (unsigned long long)wr_id + 1;
|
|
|
|
rdsdebug("ring %p ret %u wr_id %u oldest %u\n", ring, ret,
|
|
wr_id, oldest);
|
|
return ret;
|
|
}
|