[PATCH 3/3] cma: add functions to get region pages counters

[Stefan I. Strogin]

From: Dmitry Safonov <d.safonov@xxxxxxxxxxxxxxxxxxx>

Here are two functions that provide interface to compute/get used size
and size of biggest free chunk in cma region.
Added that information in cmainfo.

Signed-off-by: Dmitry Safonov <d.safonov@xxxxxxxxxxxxxxxxxxx>
---
 include/linux/cma.h |  2 ++
 mm/cma.c            | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index 9384ba6..855e6f2 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -18,6 +18,8 @@ struct cma;
 extern unsigned long totalcma_pages;
 extern phys_addr_t cma_get_base(struct cma *cma);
 extern unsigned long cma_get_size(struct cma *cma);
+extern unsigned long cma_get_used(struct cma *cma);
+extern unsigned long cma_get_maxchunk(struct cma *cma);
 
 extern int __init cma_declare_contiguous(phys_addr_t base,
 			phys_addr_t size, phys_addr_t limit,
diff --git a/mm/cma.c b/mm/cma.c
index ffaea26..5e560ed 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -78,6 +78,36 @@ unsigned long cma_get_size(struct cma *cma)
 	return cma->count << PAGE_SHIFT;
 }
 
+unsigned long cma_get_used(struct cma *cma)
+{
+	unsigned long ret = 0;
+
+	mutex_lock(&cma->lock);
+	/* pages counter is smaller than sizeof(int) */
+	ret = bitmap_weight(cma->bitmap, (int)cma->count);
+	mutex_unlock(&cma->lock);
+
+	return ret << (PAGE_SHIFT + cma->order_per_bit);
+}
+
+unsigned long cma_get_maxchunk(struct cma *cma)
+{
+	unsigned long maxchunk = 0;
+	unsigned long start, end = 0;
+
+	mutex_lock(&cma->lock);
+	for (;;) {
+		start = find_next_zero_bit(cma->bitmap, cma->count, end);
+		if (start >= cma->count)
+			break;
+		end = find_next_bit(cma->bitmap, cma->count, start);
+		maxchunk = max(end - start, maxchunk);
+	}
+	mutex_unlock(&cma->lock);
+
+	return maxchunk << (PAGE_SHIFT + cma->order_per_bit);
+}
+
 static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
 {
 	if (align_order <= cma->order_per_bit)
@@ -591,6 +621,10 @@ static int s_show(struct seq_file *m, void *p)
 	struct cma_buffer *cmabuf;
 	struct stack_trace trace;
 
+	seq_printf(m, "CMARegion stat: %8lu kB total, %8lu kB used, %8lu kB max contiguous chunk\n\n",
+		   cma_get_size(cma) >> 10,
+		   cma_get_used(cma) >> 10,
+		   cma_get_maxchunk(cma) >> 10);
 	mutex_lock(&cma->list_lock);
 
 	list_for_each_entry(cmabuf, &cma->buffers_list, list) {
-- 
2.1.0

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