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    Subject[patch v2] LMB: Add basic spin locking to lmb
    Add a spinlock to struct lmb to enforce concurrency in
    lmb_add(), lmb_remove(), lmb_analyze(), lmb_find(), and
    lmb_dump_all().

    This locking is needed for SMP systems that access the lmb structure
    during hot memory add and remove operations after secondary cpus
    have been started.

    Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
    ---

    v2: o Add locking to lmb_find().

    include/linux/lmb.h | 1
    lib/lmb.c | 62 ++++++++++++++++++++++++++++++++++++++++------------
    2 files changed, 49 insertions(+), 14 deletions(-)

    --- a/include/linux/lmb.h
    +++ b/include/linux/lmb.h
    @@ -30,6 +30,7 @@ struct lmb_region {
    };

    struct lmb {
    + spinlock_t lock;
    unsigned long debug;
    u64 rmo_size;
    struct lmb_region memory;
    --- a/lib/lmb.c
    +++ b/lib/lmb.c
    @@ -32,28 +32,33 @@ early_param("lmb", early_lmb);
    void lmb_dump_all(void)
    {
    unsigned long i;
    + struct lmb tmp;

    if (!lmb_debug)
    return;

    + spin_lock(&lmb.lock);
    + tmp = lmb;
    + spin_unlock(&lmb.lock);
    +
    pr_info("lmb_dump_all:\n");
    - pr_info(" memory.cnt = 0x%lx\n", lmb.memory.cnt);
    + pr_info(" memory.cnt = 0x%lx\n", tmp.memory.cnt);
    pr_info(" memory.size = 0x%llx\n",
    - (unsigned long long)lmb.memory.size);
    - for (i=0; i < lmb.memory.cnt ;i++) {
    + (unsigned long long)tmp.memory.size);
    + for (i=0; i < tmp.memory.cnt ;i++) {
    pr_info(" memory.region[0x%lx].base = 0x%llx\n",
    - i, (unsigned long long)lmb.memory.region[i].base);
    + i, (unsigned long long)tmp.memory.region[i].base);
    pr_info(" .size = 0x%llx\n",
    - (unsigned long long)lmb.memory.region[i].size);
    + (unsigned long long)tmp.memory.region[i].size);
    }

    - pr_info(" reserved.cnt = 0x%lx\n", lmb.reserved.cnt);
    - pr_info(" reserved.size = 0x%lx\n", lmb.reserved.size);
    - for (i=0; i < lmb.reserved.cnt ;i++) {
    + pr_info(" reserved.cnt = 0x%lx\n", tmp.reserved.cnt);
    + pr_info(" reserved.size = 0x%lx\n", tmp.reserved.size);
    + for (i=0; i < tmp.reserved.cnt ;i++) {
    pr_info(" reserved.region[0x%lx].base = 0x%llx\n",
    - i, (unsigned long long)lmb.reserved.region[i].base);
    + i, (unsigned long long)tmp.reserved.region[i].base);
    pr_info(" .size = 0x%llx\n",
    - (unsigned long long)lmb.reserved.region[i].size);
    + (unsigned long long)tmp.reserved.region[i].size);
    }
    }

    @@ -105,6 +110,8 @@ static void lmb_coalesce_regions(struct

    void __init lmb_init(void)
    {
    + spin_lock_init(&lmb.lock);
    +
    /* Create a dummy zero size LMB which will get coalesced away later.
    * This simplifies the lmb_add() code below...
    */
    @@ -122,10 +129,14 @@ void __init lmb_analyze(void)
    {
    int i;

    + spin_lock(&lmb.lock);
    +
    lmb.memory.size = 0;

    for (i = 0; i < lmb.memory.cnt; i++)
    lmb.memory.size += lmb.memory.region[i].size;
    +
    + spin_unlock(&lmb.lock);
    }

    static long lmb_add_region(struct lmb_region *rgn, u64 base, u64 size)
    @@ -194,18 +205,25 @@ static long lmb_add_region(struct lmb_re

    long lmb_add(u64 base, u64 size)
    {
    + long ret;
    struct lmb_region *_rgn = &lmb.memory;

    + spin_lock(&lmb.lock);
    +
    /* On pSeries LPAR systems, the first LMB is our RMO region. */
    if (base == 0)
    lmb.rmo_size = size;

    - return lmb_add_region(_rgn, base, size);
    + ret = lmb_add_region(_rgn, base, size);
    +
    + spin_unlock(&lmb.lock);
    + return ret;

    }

    long lmb_remove(u64 base, u64 size)
    {
    + long ret;
    struct lmb_region *rgn = &(lmb.memory);
    u64 rgnbegin, rgnend;
    u64 end = base + size;
    @@ -213,6 +231,8 @@ long lmb_remove(u64 base, u64 size)

    rgnbegin = rgnend = 0; /* supress gcc warnings */

    + spin_lock(&lmb.lock);
    +
    /* Find the region where (base, size) belongs to */
    for (i=0; i < rgn->cnt; i++) {
    rgnbegin = rgn->region[i].base;
    @@ -223,12 +243,15 @@ long lmb_remove(u64 base, u64 size)
    }

    /* Didn't find the region */
    - if (i == rgn->cnt)
    + if (i == rgn->cnt) {
    + spin_unlock(&lmb.lock);
    return -1;
    + }

    /* Check to see if we are removing entire region */
    if ((rgnbegin == base) && (rgnend == end)) {
    lmb_remove_region(rgn, i);
    + spin_unlock(&lmb.lock);
    return 0;
    }

    @@ -236,12 +259,14 @@ long lmb_remove(u64 base, u64 size)
    if (rgnbegin == base) {
    rgn->region[i].base = end;
    rgn->region[i].size -= size;
    + spin_unlock(&lmb.lock);
    return 0;
    }

    /* Check to see if the region is matching at the end */
    if (rgnend == end) {
    rgn->region[i].size -= size;
    + spin_unlock(&lmb.lock);
    return 0;
    }

    @@ -250,7 +275,10 @@ long lmb_remove(u64 base, u64 size)
    * beginging of the hole and add the region after hole.
    */
    rgn->region[i].size = base - rgn->region[i].base;
    - return lmb_add_region(rgn, end, rgnend - end);
    + ret = lmb_add_region(rgn, end, rgnend - end);
    +
    + spin_unlock(&lmb.lock);
    + return ret;
    }

    long __init lmb_reserve(u64 base, u64 size)
    @@ -502,12 +530,16 @@ int lmb_find(struct lmb_property *res)
    rstart = res->base;
    rend = rstart + res->size - 1;

    + spin_lock(&lmb.lock);
    +
    for (i = 0; i < lmb.memory.cnt; i++) {
    u64 start = lmb.memory.region[i].base;
    u64 end = start + lmb.memory.region[i].size - 1;

    - if (start > rend)
    + if (start > rend) {
    + spin_unlock(&lmb.lock);
    return -1;
    + }

    if ((end >= rstart) && (start < rend)) {
    /* adjust the request */
    @@ -517,8 +549,10 @@ int lmb_find(struct lmb_property *res)
    rend = end;
    res->base = rstart;
    res->size = rend - rstart + 1;
    + spin_unlock(&lmb.lock);
    return 0;
    }
    }
    + spin_unlock(&lmb.lock);
    return -1;
    }



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