[PATCH 2/4] bitmap_parselist: move part of logic to helpers

[Yuri Norov]

Move region checking and setting functionality of __bitmap_parselist()
to helpers.

Signed-off-by: Yury Norov <yno...@marvell.com>
---
 lib/bitmap.c | 64 +++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 53 insertions(+), 11 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index ad43ba397c58..a60fd9723677 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -477,6 +477,42 @@ int bitmap_print_to_pagebuf(bool list, char *buf, const 
unsigned long *maskp,
 }
 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
 
+/*
+ * Region 9-38:4/10 describes the following bitmap structure:
+ * 0      9  12    18                  38
+ * .........****......****......****......
+ *         ^  ^     ^                   ^
+ *      start  off   grlen            end
+ */
+struct region {
+       unsigned int start;
+       unsigned int off;
+       unsigned int grlen;
+       unsigned int end;
+};
+
+static int bitmap_set_region(const struct region *r,
+                               unsigned long *bitmap, int nbits)
+{
+       unsigned int start;
+
+       if (r->end >= nbits)
+               return -ERANGE;
+
+       for (start = r->start; start <= r->end; start += r->grlen)
+               bitmap_set(bitmap, start, min(r->end - start + 1, r->off));
+
+       return 0;
+}
+
+static int bitmap_check_region(const struct region *r)
+{
+       if (r->start > r->end || r->grlen == 0 || r->off > r->grlen)
+               return -EINVAL;
+
+       return 0;
+}
+
 /**
  * __bitmap_parselist - convert list format ASCII string to bitmap
  * @buf: read nul-terminated user string from this buffer
@@ -507,10 +543,11 @@ static int __bitmap_parselist(const char *buf, unsigned 
int buflen,
                int nmaskbits)
 {
        unsigned int a, b, old_a, old_b;
-       unsigned int group_size, used_size, off;
+       unsigned int group_size, used_size;
        int c, old_c, totaldigits, ndigits;
        const char __user __force *ubuf = (const char __user __force *)buf;
-       int at_start, in_range, in_partial_range;
+       int at_start, in_range, in_partial_range, ret;
+       struct region r;
 
        totaldigits = c = 0;
        old_a = old_b = 0;
@@ -599,15 +636,20 @@ static int __bitmap_parselist(const char *buf, unsigned 
int buflen,
                /* if no digit is after '-', it's wrong*/
                if (at_start && in_range)
                        return -EINVAL;
-               if (!(a <= b) || group_size == 0 || !(used_size <= group_size))
-                       return -EINVAL;
-               if (b >= nmaskbits)
-                       return -ERANGE;
-               while (a <= b) {
-                       off = min(b - a + 1, used_size);
-                       bitmap_set(maskp, a, off);
-                       a += group_size;
-               }
+
+               r.start = a;
+               r.off = used_size;
+               r.grlen = group_size;
+               r.end = b;
+
+               ret = bitmap_check_region(&r);
+               if (ret)
+                       return ret;
+
+               ret = bitmap_set_region(&r, maskp, nmaskbits);
+               if (ret)
+                       return ret;
+
        } while (buflen && c == ',');
        return 0;
 }
-- 
2.17.1