lib/libtnfprobe/tnf_buf.c

	tnf_buf.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 *  Copyright 1994-2003 Sun Microsytems, Inc.  All rights reserved.
 *  Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/types.h>
#include <sys/param.h>
#ifdef _KERNEL
#include <sys/systm.h>      /* for bzero */
#include <sys/spl.h>
#include <sys/cmn_err.h>
#else  /* _KERNEL */
#include <string.h>     /* for memset */
#endif /* _KERNEL */

#include "tnf_buf.h"

#ifdef TNFWB_DEBUG
#ifdef _KERNEL
#error TNFWB_DEBUG
#else  /* _KERNEL */
#include <stdio.h>
#include <thread.h>
#endif /* _KERNEL */
#endif /* TNFW_DEBUG */

/*
 * Defines
 */

#define TNFW_B_FW_INVALID       0xffffffff
#define TNFW_B_ALLOC_LO_SELECTOR    0x1
#define TNFW_B_MAXALLOCTRY      200

#ifdef TNF_BLOCK_STATS
static struct {
    int tnf_block_allocs;
    int tnf_block_tries;
    int tnf_max_block_tries;
    int tnf_tag_blocks;
    int tnf_generation_laps;
    int tnf_a_locks;
    int tnf_b_locks;
} tnf_block_stats;
#endif

/*
 * Regular record tag pointer - CAUTION - has to be in sync with tnf_tag
 * macro in writer.h
 */
#define TNFW_B_TAG_DIFF(item, ref)              \
    ((TNF_REF32_MAKE_PERMANENT((tnf_ref32_t)        \
        ((char *)(item) - (char *)(ref)))) | TNF_REF32_T_TAG)

/*
 * Exported interface by buffering layer to indicate where fowarding ptrs
 * for file header and block header are.
 */
static tnf_buf_header_t forwarding_ptrs = {NULL, NULL, NULL};
tnf_buf_header_t *_tnf_buf_headers_p = &forwarding_ptrs;

#ifdef _KERNEL
extern volatile caddr_t tnf_buf;

static kmutex_t hintlock;
#endif

/*
 * (Private) Allocate a new block.  Return NULL on failure.  'istag'
 * is true if the block is to be non-reclaimable.
 */
static tnf_block_header_t *
tnfw_b_alloc_block(TNFW_B_WCB *wcb, enum tnf_alloc_mode istag)
{
    tnf_block_header_t  *block;
    uint_t          hint_hi, hint_lo;
    uint_t          new_hint_hi, new_hint_lo;
    uint_t          generation;
    uint_t          blocknum;
    uint_t          prev_gen = 0;
    uint_t          prev_block = 0;
    uint_t          i, b;
    boolean_t       gotit = B_FALSE;
    volatile tnf_buf_file_header_t  *fh;
#ifdef TNF_BLOCK_STATS
    register int tag_blocks = 0, generation_laps = 0, a_locks = 0,
        b_locks = 0;
#endif

#ifdef _TNF_VERBOSE
    fprintf(stderr, "tnfw_b_alloc_block: \n");
#endif

    if (_tnfw_b_control->tnf_state != TNFW_B_RUNNING) {
#ifndef _KERNEL
        if (_tnfw_b_control->tnf_state == TNFW_B_NOBUFFER)
            if (_tnfw_b_control->tnf_init_callback() == 0)
                return (NULL);
#endif /* _KERNEL */
        if (TNFW_B_IS_STOPPED(_tnfw_b_control->tnf_state))
            return (NULL);
        if (_tnfw_b_control->tnf_state == TNFW_B_BROKEN)
            return (NULL);
    }

    /* LINTED pointer cast may result in improper alignment */
    fh = (volatile tnf_buf_file_header_t *)_tnfw_b_control->tnf_buffer;
    if (!wcb->tnfw_w_initialized) {
        /* Get the block shift and generation shift values. */
        b = 1;
        wcb->tnfw_w_block_shift = wcb->tnfw_w_gen_shift = 0;
        while (b != fh->com.block_size) {
            b <<= 1;
            ++wcb->tnfw_w_block_shift;
        }
        b = 1;
        while (b < fh->com.block_count) {
            b <<= 1;
            ++wcb->tnfw_w_gen_shift;
        }
        wcb->tnfw_w_pid = _tnfw_b_control->tnf_pid;
        wcb->tnfw_w_initialized = B_TRUE;
    }

    /*
     * If we need a tag block, check the reserved tag block space
     * first.  fh->next_tag_alloc is only a hint; it is updated
     * without concurrency control.
     */
    if (istag && fh->next_tag_alloc < TNFW_B_DATA_BLOCK_BEGIN) {
        i = fh->next_tag_alloc;
        do {
            /* LINTED pointer cast */
            block = (tnf_block_header_t *) ((char *) fh + i);
            if (!tnfw_b_get_lock(&block->A_lock) &&
                block->generation == 0)
                break;
            i += fh->com.block_size;
        } while (i < TNFW_B_DATA_BLOCK_BEGIN);
        if (i < TNFW_B_DATA_BLOCK_BEGIN) {
            if (i > fh->next_tag_alloc)
                fh->next_tag_alloc = i;
            blocknum = i >> wcb->tnfw_w_block_shift;
            if (blocknum > fh->com.blocks_valid)
                fh->com.blocks_valid = blocknum;
            /* LINTED pointer subtraction casted to 32 bits */
            block->tag = TNFW_B_TAG_DIFF(
                forwarding_ptrs.fw_block_header, fh);
            /* LINTED constant truncated by assignment */
            block->generation = TNF_TAG_GENERATION_NUM;
            block->bytes_valid = sizeof (tnf_block_header_t);
            block->next_block = NULL;
            tnfw_b_clear_lock(&block->A_lock);
            return (block);
        }
    }

    for (i = 0; !gotit && i != TNFW_B_MAXALLOCTRY; ++i) {
        hint_hi = fh->next_alloc.hi;
        hint_lo = (hint_hi & TNFW_B_ALLOC_LO_SELECTOR)
            ? fh->next_alloc.lo[1] : fh->next_alloc.lo[0];
        generation = (hint_hi << (32 - wcb->tnfw_w_gen_shift)) |
            (hint_lo >> wcb->tnfw_w_gen_shift);
        blocknum = hint_lo & ((1 << wcb->tnfw_w_gen_shift) - 1);
#ifdef TNFWB_DEBUG
        fprintf(stderr, "alloc_block (%d): read hint (%d, %d)\n",
            thr_self(), generation, blocknum);
#endif
        if ((prev_gen == generation && prev_block > blocknum) ||
            prev_gen > generation) {
            generation = prev_gen;
            blocknum = prev_block;
        }
#ifdef TNFWB_DEBUG
        fprintf(stderr,
            "alloc_block (%d): trying blocknum = %d, gen %d\n",
            thr_self(), blocknum, generation);
#endif
        block = (tnf_block_header_t *)
        /* LINTED pointer cast may result in improper alignment */
            ((char *)fh + blocknum * fh->com.block_size);
#ifdef TNF_BLOCK_STATS
        if (block->generation == TNF_TAG_GENERATION_NUM)
            ++tag_blocks;
        else if (block->generation >= generation)
            ++generation_laps;
        else if (tnfw_b_get_lock(&block->A_lock))
            ++a_locks;
        else if (block->generation == TNF_TAG_GENERATION_NUM)
            ++tag_blocks;
        else if (block->generation >= generation)
            ++generation_laps;
        else if (tnfw_b_get_lock(&block->B_lock)) {
            tnfw_b_clear_lock(&block->A_lock);
            ++b_locks;
        } else
            gotit = B_TRUE;

#else
        if (block->generation < generation &&
            !tnfw_b_get_lock(&block->A_lock)) {
            if (block->generation < generation &&
                !tnfw_b_get_lock(&block->B_lock)) {
                gotit = B_TRUE;
            } else {
                tnfw_b_clear_lock(&block->A_lock);
            }
        }
#endif
        prev_block = blocknum + 1;
        prev_gen = generation;
        if (prev_block == fh->com.block_count) {
            prev_block =
                TNFW_B_DATA_BLOCK_BEGIN >> wcb->tnfw_w_block_shift;
            ++prev_gen;
        }
        if (blocknum > fh->com.blocks_valid) {
            fh->com.blocks_valid = blocknum;
        }
    }

    if (i == TNFW_B_MAXALLOCTRY) {
        _tnfw_b_control->tnf_state = TNFW_B_BROKEN;
        return (NULL);
    }
#ifdef TNFWB_DEBUG
    fprintf(stderr,
        "alloc_block (%d): got blocknum = %d, gen %d, block at 0x%x\n",
        thr_self(), blocknum, generation, block);
#endif
    /* LINTED pointer subtraction casted to 32 bits */
    block->tag = TNFW_B_TAG_DIFF(forwarding_ptrs.fw_block_header, fh);
    block->generation = (istag) ? TNF_TAG_GENERATION_NUM : generation;
    block->bytes_valid = sizeof (tnf_block_header_t);
    block->next_block = NULL;
    if (istag) {
        tnfw_b_clear_lock(&block->A_lock);
    }
    tnfw_b_clear_lock(&block->B_lock);

    /*
     * Read the hint one more time, only update it if we'll be increasing
     * it
     */
    new_hint_hi = prev_gen >> (32 - wcb->tnfw_w_gen_shift);
    new_hint_lo = prev_block | (prev_gen << wcb->tnfw_w_gen_shift);
#ifdef _KERNEL
    mutex_enter(&hintlock);
#endif
    hint_hi = fh->next_alloc.hi;
    hint_lo = (hint_hi & TNFW_B_ALLOC_LO_SELECTOR) ?
        fh->next_alloc.lo[1] : fh->next_alloc.lo[0];

    if ((new_hint_hi == hint_hi && new_hint_lo > hint_lo) ||
        new_hint_hi > hint_hi) {
        /*
         * Order is important here!  It is the write to next_alloc.hi
         * that atomically records the new value.
         */
        if (new_hint_hi & TNFW_B_ALLOC_LO_SELECTOR)
            fh->next_alloc.lo[1] = new_hint_lo;
        else
            fh->next_alloc.lo[0] = new_hint_lo;
        fh->next_alloc.hi = new_hint_hi;
#ifdef TNFWB_DEBUG
        fprintf(stderr, "alloc_block (%d): wrote hint (%d, %d)\n",
            thr_self(), prev_gen, prev_block);
#endif
    }
#ifdef _KERNEL
    mutex_exit(&hintlock);
#endif
#ifdef TNF_BLOCK_STATS
    ++tnf_block_stats.tnf_block_allocs;
    tnf_block_stats.tnf_block_tries += i;
    if (i > tnf_block_stats.tnf_max_block_tries) {
        tnf_block_stats.tnf_max_block_tries = i;
        tnf_block_stats.tnf_tag_blocks = tag_blocks;
        tnf_block_stats.tnf_generation_laps = generation_laps;
        tnf_block_stats.tnf_a_locks = a_locks;
        tnf_block_stats.tnf_b_locks = b_locks;
    }
#endif
    return (block);
}

static void release_block_from_pos(TNFW_B_POS * pos)
{
    if (pos->tnfw_w_block == NULL)
        return;
    if (pos->tnfw_w_uncommitted != NULL)
        return;
    tnfw_b_clear_lock(&pos->tnfw_w_block->A_lock);
    pos->tnfw_w_block = NULL;
}

void
tnfw_b_release_block(TNFW_B_WCB * wcb)
{
    if (wcb == NULL)
        return;
    release_block_from_pos(&wcb->tnfw_w_tag_pos);
    release_block_from_pos(&wcb->tnfw_w_pos);
}

/*
 * Initialize a buffer.  NOT RE-ENTRANT!  Block sizes other than 512
 * are currently rejected.  The code "ought to work" with any block
 * size that is an integral power of 2.  'zfod' states whether we
 * can assume that the buffer is zero-filled (or paged-in zero-fill-on-demand).
 */
TNFW_B_STATUS
tnfw_b_init_buffer(char *buf, int blocks, int block_size, boolean_t zfod)

{
    int     block_shift, gen_shift;
    int     i;
    int file_size;
    unsigned b;
    tnf_block_header_t *block;
    /* LINTED pointer cast may result in improper alignment */
    tnf_buf_file_header_t *fh = (tnf_buf_file_header_t *)buf;

#ifdef _TNF_VERBOSE
    fprintf(stderr, "tnfw_b_init_buffer: \n");
#endif

    /* Check for 512 could go away. */
    if (block_size != 512 || block_size < sizeof (tnf_buf_file_header_t))
        return (TNFW_B_BAD_BLOCK_SIZE);
    /*
     * Check to see if block size is a power of 2, and get
     * log2(block size).
     */
    for (b = (unsigned)block_size, block_shift = 0; (b & 1) == 0; b >>= 1)
        ++block_shift;
    if (b != 1)
        return (TNFW_B_BAD_BLOCK_SIZE);
    gen_shift = 0;
    while (b < blocks) {
        b <<= 1;
        ++gen_shift;
    }
    /* reserve first two words for file header tag and block header tag */
    forwarding_ptrs.fw_file_header  = (char *)fh + block_size;
    forwarding_ptrs.fw_block_header = (char *)fh + block_size +
        sizeof (tnf_ref32_t);
    forwarding_ptrs.fw_root = (char *)fh + block_size +
        (2 * sizeof (tnf_ref32_t));
    /* LINTED size of tnf_ref_32_t known to be 32 */
    fh->next_fw_alloc = block_size + (3 * sizeof (tnf_ref32_t));
    /* fill in rest of file header */
    fh->magic = TNF_MAGIC;
    /* Self relative pointer to tag */
    /* LINTED pointer subtraction casted to 32 bits */
    fh->com.tag = TNFW_B_TAG_DIFF(forwarding_ptrs.fw_file_header, fh);
    fh->com.file_version = TNF_FILE_VERSION;
    fh->com.file_header_size = sizeof (tnf_file_header_t);
    /* fill in fh->com.file_log_size */
    b = 1;
    file_size = blocks * block_size;
    fh->com.file_log_size = 0;
    while (b < file_size) {
        b <<= 1;
        ++fh->com.file_log_size;
    }

    fh->com.block_header_size = sizeof (tnf_block_header_t);
    fh->com.block_size = block_size;
    fh->com.directory_size = TNFW_B_FW_ZONE;
    fh->com.block_count = blocks;
    fh->com.blocks_valid = TNFW_B_FW_ZONE >> block_shift;
    if (fh->com.blocks_valid == 0)
        fh->com.blocks_valid = 1;
    fh->next_tag_alloc = TNFW_B_FW_ZONE;
    fh->next_alloc.hi = 0;
    fh->next_alloc.lo[0] =
        (1 << gen_shift) | (TNFW_B_DATA_BLOCK_BEGIN >> block_shift);
#ifdef TNFWB_DEBUG
    fprintf(stderr, "gen_shift = %d, blocks_valid = %d\n",
        gen_shift, fh->com.blocks_valid);
    fprintf(stderr, "alloc hint initialized to (%d, %d, %d)\n",
        fh->next_alloc.hi, fh->next_alloc.lo[0], fh->next_alloc.lo[1]);
#endif
    if (!zfod) {
        for (i = 1; i < (TNFW_B_FW_ZONE >> block_shift); ++i) {
#ifdef _KERNEL
            bzero(buf + (i << block_shift), block_size);
#else
            (void) memset(buf + (i << block_shift), 0, block_size);
#endif
        }
        for (; i != blocks; ++i) {
            block = (tnf_block_header_t *)
                /* LINTED pointer cast */
                (buf + (i << block_shift));
            block->tag = 0;
            block->generation = 0;
            tnfw_b_clear_lock(&block->A_lock);
            tnfw_b_clear_lock(&block->B_lock);
        }
    }
#ifdef _KERNEL
    mutex_init(&hintlock, "tnf buffer hint lock", MUTEX_SPIN_DEFAULT,
        (void *) ipltospl(LOCK_LEVEL));
#endif
    return (TNFW_B_OK);
}

/*
 *
 */
void *
tnfw_b_alloc(TNFW_B_WCB *wcb, size_t size, enum tnf_alloc_mode istag)
{
    TNFW_B_POS  *pos;
    int         offset;
    void        *destp;
    volatile tnf_buf_file_header_t *fh;
    tnf_block_header_t *block, *new_block;

#ifdef _TNF_VERBOSE
    fprintf(stderr, "tnfw_b_alloc: \n");
#endif

    if (_tnfw_b_control->tnf_state != TNFW_B_RUNNING) {
        if (TNFW_B_IS_STOPPED(_tnfw_b_control->tnf_state))
            return (NULL);
        if (_tnfw_b_control->tnf_state == TNFW_B_FORKED &&
            _tnfw_b_control->tnf_pid != wcb->tnfw_w_pid) {
            wcb->tnfw_w_pos.tnfw_w_block =
                wcb->tnfw_w_pos.tnfw_w_uncommitted =
                wcb->tnfw_w_tag_pos.tnfw_w_block =
                wcb->tnfw_w_tag_pos.tnfw_w_uncommitted = NULL;
            wcb->tnfw_w_pid = _tnfw_b_control->tnf_pid;
            _tnfw_b_control->tnf_fork_callback();
        }
    }

    /* Round size up to a multiple of 8. */
    size = (size + 7) & ~7;

    /* LINTED pointer cast may result in improper alignment */
    fh = (volatile tnf_buf_file_header_t *)_tnfw_b_control->tnf_buffer;
    pos = (istag) ? &wcb->tnfw_w_tag_pos : &wcb->tnfw_w_pos;
    block = pos->tnfw_w_block;
    /* Check size within range. */
#ifdef TNFWB_SAFER
    if (size > fh->com.block_size - sizeof (tnf_block_header_t))
        /* TNFW_B_RECORD_TOO_BIG */
        return (NULL);
#endif
    offset = pos->tnfw_w_write_off;
#ifdef TNFWB_MAY_RELEASE_A_LOCK
    if (block != NULL && wcb->tnfw_w_a_lock_released) {
        /* re-acquire the A-lock for the current block */
        if (!tnfw_b_get_lock(&block->A_lock)) {
            wcb->tnfw_w_a_lock_released = B_FALSE;
            if (wcb->tnfw_w_generation != block->generation) {
                tnfw_b_clear_lock(&block->A_lock);
                wcb->tnfw_w_pos.tnfw_w_block = NULL;
            }
        } else {
            wcb->tnfw_w_pos.tnfw_w_block = NULL;
        }
    }
#endif
    if (block == NULL || offset + size > fh->com.block_size) {
        new_block = tnfw_b_alloc_block(wcb, istag);
        if (new_block == NULL) {
            /* TNFW_B_ACKPHT */
            return (NULL);
        }
#ifdef TNFWB_DEBUG
        fprintf(stderr,
            "wcb 0x%x: new block at 0x%x, old block is 0x%x, "
            "uncommitted is 0x%x\n",
            wcb, new_block, block, pos->tnfw_w_uncommitted);
#endif
        if (block != NULL) {
            /* XXXX is this what we want for padding? */
#ifdef _KERNEL
            (void) bzero((char *)block + offset,
                fh->com.block_size - offset);
#else
            (void) memset((char *)block + offset, 0,
                fh->com.block_size - offset);
#endif
            if (pos->tnfw_w_uncommitted == NULL) {
#ifdef TNFWB_MAY_RELEASE_A_LOCK
                /* Could still be holding the A-lock on block */
                if (!wcb->tnfw_w_a_lock_released)
                    tnfw_b_clear_lock(&block->A_lock);
#else
                /* Definitely still holding the A-lock */
                tnfw_b_clear_lock(&block->A_lock);
#endif  /* TNFWB_MAY_RELEASE_A_LOCK */
            }
        }
        /* Add new_block to the list of uncommitted blocks. */
        if (pos->tnfw_w_uncommitted == NULL) {
            pos->tnfw_w_uncommitted = new_block;
        } else {
            /* Assert(block != NULL); */
            block->next_block = new_block;
        }
        pos->tnfw_w_block = new_block;
        pos->tnfw_w_write_off = new_block->bytes_valid;
    } else if (pos->tnfw_w_uncommitted == NULL) {
        pos->tnfw_w_uncommitted = block;
    }
    destp = (char *)pos->tnfw_w_block + pos->tnfw_w_write_off;
    pos->tnfw_w_write_off += size;
    /*
     * Unconditionally write a 0 into the last word allocated,
     * in case we left an alignment gap.  (Assume that doing an
     * unconditional write is cheaper than testing and branching
     * around the write half the time.)
     */
    /* LINTED pointer cast may result in improper alignment */
    *((int *)((char *) destp + size - sizeof (int))) = 0;

#ifdef _TNF_VERBOSE
    fprintf(stderr, "tnfw_b_alloc returning %p\n", destp);
#endif
    return (destp);
}

/*
 *
 */
TNFW_B_STATUS
tnfw_b_xcommit(TNFW_B_WCB *wcb)
{
    TNFW_B_POS *pos;
    tnf_block_header_t *block;
    volatile tnf_buf_file_header_t *fh =
        /* LINTED pointer cast may result in improper alignment */
        (volatile tnf_buf_file_header_t *)_tnfw_b_control->tnf_buffer;

#ifdef TNFWB_DEBUG
    fprintf(stderr, "tnfw_b_xcommit \n");
#endif

    /*
     * cope with the normal record block(s) first
     */

    pos = &wcb->tnfw_w_pos;
    block = pos->tnfw_w_uncommitted;
    while (block && (block != pos->tnfw_w_block)) {
#ifdef TNFWB_DEBUG
        fprintf(stderr, "commit %d: block = 0x%x, last = 0x%x\n",
            block->generation, block, pos->tnfw_w_block);
#endif
        block->bytes_valid = fh->com.block_size;
        pos->tnfw_w_uncommitted = block->next_block;
        tnfw_b_clear_lock(&block->A_lock);
        block = pos->tnfw_w_uncommitted;
    }
    if (block != NULL) {
#ifdef TNFWB_DEBUG
        fprintf(stderr, "commit last %d: block = 0x%x, offset = 0x%x\n",
            block->generation, block, pos->tnfw_w_write_off);
#endif
        block->bytes_valid = pos->tnfw_w_write_off;
    }
    pos->tnfw_w_uncommitted = NULL;
#ifdef TNFWB_MAY_RELEASE_A_LOCK
    if (0) {    /* XXXX Do we or don't we clear this lock? */
        wcb->tnfw_w_generation = block->generation;
        tnfw_b_clear_lock(&block->A_lock);
        wcb->tnfw_w_a_lock_released = B_TRUE;
    }
#endif

    /*
     * cope with the tag block(s)
     */

    pos = &wcb->tnfw_w_tag_pos;
    block = pos->tnfw_w_uncommitted;
    while (block && (block != pos->tnfw_w_block)) {
#ifdef TNFWB_DEBUG
        fprintf(stderr, "commit %d: block = 0x%x, last = 0x%x\n",
            thr_self(), block, pos->tnfw_w_block);
#endif
        block->bytes_valid = fh->com.block_size;
        pos->tnfw_w_uncommitted = block->next_block;
        block = pos->tnfw_w_uncommitted;
    }
    if (block != NULL)
        block->bytes_valid = pos->tnfw_w_write_off;
    pos->tnfw_w_uncommitted = NULL;
    return (TNFW_B_OK);
}

/*
 *
 */
TNFW_B_STATUS
tnfw_b_xabort(TNFW_B_WCB *wcb)
{
    TNFW_B_POS *pos = &wcb->tnfw_w_pos;
    tnf_block_header_t *block, *next;
    volatile tnf_buf_file_header_t *fh =
        /* LINTED pointer cast may result in improper alignment */
        (volatile tnf_buf_file_header_t *)_tnfw_b_control->tnf_buffer;

    block = pos->tnfw_w_block = pos->tnfw_w_uncommitted;
    if (block != NULL) {
        pos->tnfw_w_write_off = block->bytes_valid;
#ifdef TNFWB_MAY_RELEASE_A_LOCK
        if (0) {        /* XXXX */
            tnfw_b_clear_lock(&block->A_lock);
            wcb->tnfw_w_generation = block->generation;
            wcb->tnfw_w_a_lock_released = B_TRUE;
        }
#endif
        block = block->next_block;
    }
    while (block != NULL) {
        next = block->next_block;
        tnfw_b_clear_lock(&block->A_lock);
        block = next;
    }
    pos->tnfw_w_uncommitted = NULL;
    pos = &wcb->tnfw_w_tag_pos;
    block = pos->tnfw_w_uncommitted;
    while (block && (block != pos->tnfw_w_block)) {
        block->bytes_valid = fh->com.block_size;
        pos->tnfw_w_uncommitted = block->next_block;
        block = pos->tnfw_w_uncommitted;
    }
    if (block != NULL)
        block->bytes_valid = pos->tnfw_w_write_off;
    pos->tnfw_w_uncommitted = NULL;
    return (TNFW_B_OK);
}

/*
 * The kernel version is different because we can use a spin mutex
 * in the kernel, and not all SPARC systems support the SWAP instruction.
 */
#ifdef _KERNEL
/*ARGSUSED0*/
tnf_uint32_t *
tnfw_b_fw_alloc(TNFW_B_WCB *wcb)
{
    tnf_uint32_t *ret_val;
    volatile tnf_buf_file_header_t *fh =
        /* LINTED pointer cast may result in improper alignment */
        (volatile tnf_buf_file_header_t *)_tnfw_b_control->tnf_buffer;
    tnf_uint32_t *zone_end = (tnf_uint32_t *)((char *)fh + TNFW_B_FW_ZONE);
    mutex_enter(&hintlock);
    ret_val = (tnf_uint32_t *)((char *)fh + fh->next_fw_alloc);
    if (ret_val != zone_end)
        fh->next_fw_alloc += sizeof (tnf_uint32_t);
    mutex_exit(&hintlock);
    return ((ret_val != zone_end) ? ret_val : NULL);
}

#else

/*ARGSUSED0*/
tnf_uint32_t *
tnfw_b_fw_alloc(TNFW_B_WCB *wcb)
{
    volatile tnf_buf_file_header_t *fh =
        /* LINTED pointer cast may result in improper alignment */
        (volatile tnf_buf_file_header_t *)_tnfw_b_control->tnf_buffer;
    /* LINTED pointer cast may result in improper alignment */
    uint_t *hint = (uint_t *)((uintptr_t)fh + fh->next_fw_alloc);
    /* LINTED pointer cast may result in improper alignment */
    ulong_t *zone_end = (ulong_t *)((uintptr_t)fh + TNFW_B_FW_ZONE);
    u_long swapin;
    char tmp_buf[512];
    tnf_uint32_t *retval;

#ifdef VERYVERBOSE
        sprintf(tmp_buf, "tnfw_b_vw_alloc: begin\n");
        (void) write(2, tmp_buf, strlen(tmp_buf));
#endif

#ifdef VERYVERBOSE
        sprintf(tmp_buf, "tnfw_b_vw_alloc: (1)hint=%p\n", hint);
        (void) write(2, tmp_buf, strlen(tmp_buf));
#endif

    while ((uintptr_t)hint != (uintptr_t)zone_end) {
#ifdef VERYVERBOSE
        sprintf(tmp_buf, "tnfw_b_vw_alloc: (2)hint=%p,zone_end=%p\n",
            hint, zone_end);
        (void) write(2, tmp_buf, strlen(tmp_buf));
#endif

#ifdef VERYVERBOSE
    sprintf(tmp_buf, "tnfw_b_fw_alloc: fh = %p, next->alloc = %d\n",
        fh, fh->next_fw_alloc);
    (void) write(2, tmp_buf, strlen(tmp_buf));

        sprintf(tmp_buf, "tnfw_b_vw_alloc: about to deref hint\n");
        (void) write(2, tmp_buf, strlen(tmp_buf));

        sprintf(tmp_buf, "tnfw_b_vw_alloc: *hint=%ld\n", *hint);
        (void) write(2, tmp_buf, strlen(tmp_buf));
#endif
        if (*hint == 0) {
            swapin = tnfw_b_atomic_swap(hint, TNFW_B_FW_INVALID);
            if (swapin != 0) {
                if (swapin != (unsigned)TNFW_B_FW_INVALID) {
                    /* restore */
                    *hint = swapin;
                }
            } else {
                break;
            }
        }
        ++hint;
#ifdef VERYVERBOSE
        sprintf(tmp_buf, "tnfw_b_vw_alloc: (3)hint=%p\n", hint);
        (void) write(2, tmp_buf, strlen(tmp_buf));
#endif

    }
    /* LINTED pointer subtraction casted to 32 bits */
    fh->next_fw_alloc = (uint_t) ((char *)hint - (char *)fh);
    retval = (((uintptr_t)hint != (uintptr_t)zone_end) ?
        (tnf_uint32_t *)hint : NULL);

#ifdef VERYVERBOSE
    sprintf(tmp_buf, "tnfw_b_vw_alloc: returning %p", retval);
    (void) write(2, tmp_buf, strlen(tmp_buf));
#endif

    return (retval);
}

#endif  /* _KERNEL */