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    SubjectRe: [PATCH v2 4/7] AMSO1100 Memory Management.
    On Wed, 07 Jun 2006 15:06:55 -0500
    Steve Wise <swise@opengridcomputing.com> wrote:

    >
    > +void c2_free(struct c2_alloc *alloc, u32 obj)
    > +{
    > + spin_lock(&alloc->lock);
    > + clear_bit(obj, alloc->table);
    > + spin_unlock(&alloc->lock);
    > +}

    The spinlock is unneeded here.


    What does all the code in this file do, anyway? It looks totally generic
    (and hence inappropriate for drivers/infiniband/hw/amso1100/) and somewhat
    similar to idr trees, perhaps.

    > +int c2_array_set(struct c2_array *array, int index, void *value)
    > +{
    > + int p = (index * sizeof(void *)) >> PAGE_SHIFT;
    > +
    > + /* Allocate with GFP_ATOMIC because we'll be called with locks held. */
    > + if (!array->page_list[p].page)
    > + array->page_list[p].page =
    > + (void **) get_zeroed_page(GFP_ATOMIC);
    > +
    > + if (!array->page_list[p].page)
    > + return -ENOMEM;

    This _will_ happen under load. What will the result of that be, in the
    context of thise driver?

    This function is incorrectly designed - it should receive a gfp_t argument.
    Because you don't *know* that the caller will always hold a spinlock. And
    GFP_KERNEL is far, far stronger than GFP_ATOMIC.

    > +static int c2_alloc_mqsp_chunk(gfp_t gfp_mask, struct sp_chunk **head)
    > +{
    > + int i;
    > + struct sp_chunk *new_head;
    > +
    > + new_head = (struct sp_chunk *) __get_free_page(gfp_mask | GFP_DMA);

    Why is __GFP_DMA in there? Unless you've cornered the ISA bus infiniband
    market, it's likely to be wrong.


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