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Subject[tip:x86/memblock] memblock: Implement for_each_free_mem_range()
Commit-ID:  35fd0808d7d8d001cd72f112e3bca84664b596a3
Gitweb: http://git.kernel.org/tip/35fd0808d7d8d001cd72f112e3bca84664b596a3
Author: Tejun Heo <tj@kernel.org>
AuthorDate: Tue, 12 Jul 2011 11:15:59 +0200
Committer: H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 14 Jul 2011 11:47:47 -0700

memblock: Implement for_each_free_mem_range()

Implement for_each_free_mem_range() which iterates over free memory
areas according to memblock (memory && !reserved). This will be used
to simplify memblock users.

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1310462166-31469-7-git-send-email-tj@kernel.org
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
include/linux/memblock.h | 20 ++++++++++++
mm/memblock.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 96 insertions(+), 0 deletions(-)
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index c36a55d..31def58 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -61,6 +61,26 @@ extern long memblock_remove(phys_addr_t base, phys_addr_t size);
extern long memblock_free(phys_addr_t base, phys_addr_t size);
extern long memblock_reserve(phys_addr_t base, phys_addr_t size);

+extern void __next_free_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
+ phys_addr_t *out_end, int *out_nid);
+
+/**
+ * for_each_free_mem_range - iterate through free memblock areas
+ * @i: u64 used as loop variable
+ * @nid: node selector, %MAX_NUMNODES for all nodes
+ * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ * @p_nid: ptr to int for nid of the range, can be %NULL
+ *
+ * Walks over free (memory && !reserved) areas of memblock. Available as
+ * soon as memblock is initialized.
+ */
+#define for_each_free_mem_range(i, nid, p_start, p_end, p_nid) \
+ for (i = 0, \
+ __next_free_mem_range(&i, nid, p_start, p_end, p_nid); \
+ i != (u64)ULLONG_MAX; \
+ __next_free_mem_range(&i, nid, p_start, p_end, p_nid))
+
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
extern int memblock_set_node(phys_addr_t base, phys_addr_t size, int nid);

diff --git a/mm/memblock.c b/mm/memblock.c
index e815f4b..c4a8750 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -461,6 +461,82 @@ long __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
return memblock_add_region(_rgn, base, size);
}

+/**
+ * __next_free_mem_range - next function for for_each_free_mem_range()
+ * @idx: pointer to u64 loop variable
+ * @nid: nid: node selector, %MAX_NUMNODES for all nodes
+ * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ * @p_nid: ptr to int for nid of the range, can be %NULL
+ *
+ * Find the first free area from *@idx which matches @nid, fill the out
+ * parameters, and update *@idx for the next iteration. The lower 32bit of
+ * *@idx contains index into memory region and the upper 32bit indexes the
+ * areas before each reserved region. For example, if reserved regions
+ * look like the following,
+ *
+ * 0:[0-16), 1:[32-48), 2:[128-130)
+ *
+ * The upper 32bit indexes the following regions.
+ *
+ * 0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
+ *
+ * As both region arrays are sorted, the function advances the two indices
+ * in lockstep and returns each intersection.
+ */
+void __init_memblock __next_free_mem_range(u64 *idx, int nid,
+ phys_addr_t *out_start,
+ phys_addr_t *out_end, int *out_nid)
+{
+ struct memblock_type *mem = &memblock.memory;
+ struct memblock_type *rsv = &memblock.reserved;
+ int mi = *idx & 0xffffffff;
+ int ri = *idx >> 32;
+
+ for ( ; mi < mem->cnt; mi++) {
+ struct memblock_region *m = &mem->regions[mi];
+ phys_addr_t m_start = m->base;
+ phys_addr_t m_end = m->base + m->size;
+
+ /* only memory regions are associated with nodes, check it */
+ if (nid != MAX_NUMNODES && nid != memblock_get_region_node(m))
+ continue;
+
+ /* scan areas before each reservation for intersection */
+ for ( ; ri < rsv->cnt + 1; ri++) {
+ struct memblock_region *r = &rsv->regions[ri];
+ phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
+ phys_addr_t r_end = ri < rsv->cnt ? r->base : ULLONG_MAX;
+
+ /* if ri advanced past mi, break out to advance mi */
+ if (r_start >= m_end)
+ break;
+ /* if the two regions intersect, we're done */
+ if (m_start < r_end) {
+ if (out_start)
+ *out_start = max(m_start, r_start);
+ if (out_end)
+ *out_end = min(m_end, r_end);
+ if (out_nid)
+ *out_nid = memblock_get_region_node(m);
+ /*
+ * The region which ends first is advanced
+ * for the next iteration.
+ */
+ if (m_end <= r_end)
+ mi++;
+ else
+ ri++;
+ *idx = (u32)mi | (u64)ri << 32;
+ return;
+ }
+ }
+ }
+
+ /* signal end of iteration */
+ *idx = ULLONG_MAX;
+}
+
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
/*
* Common iterator interface used to define for_each_mem_range().

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