[PATCH v4 3/5] mm: move ``get_order_from_str()`` to internal.h

[Maíra Canal]

From: Maíra Canal <mairaca...@riseup.net>

In order to implement a kernel parameter similar to ``thp_anon=`` for
shmem, we'll need the function ``get_order_from_str()``.

Instead of duplicating the function, move the function to a shared
header, in which both mm/shmem.c and mm/huge_memory.c will be able to
use it.

Signed-off-by: Maíra Canal <mairaca...@riseup.net>
---
 mm/huge_memory.c | 38 +++++++++++++++-----------------------
 mm/internal.h    | 22 ++++++++++++++++++++++
 2 files changed, 37 insertions(+), 23 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f92068864469..a6edbd8c4f49 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -958,26 +958,6 @@ static int __init setup_transparent_hugepage(char *str)
 }
 __setup("transparent_hugepage=", setup_transparent_hugepage);
 
-static inline int get_order_from_str(const char *size_str)
-{
-       unsigned long size;
-       char *endptr;
-       int order;
-
-       size = memparse(size_str, &endptr);
-
-       if (!is_power_of_2(size))
-               goto err;
-       order = get_order(size);
-       if (BIT(order) & ~THP_ORDERS_ALL_ANON)
-               goto err;
-
-       return order;
-err:
-       pr_err("invalid size %s in thp_anon boot parameter\n", size_str);
-       return -EINVAL;
-}
-
 static char str_dup[PAGE_SIZE] __initdata;
 static int __init setup_thp_anon(char *str)
 {
@@ -1007,10 +987,22 @@ static int __init setup_thp_anon(char *str)
                                start_size = strsep(&subtoken, "-");
                                end_size = subtoken;
 
-                               start = get_order_from_str(start_size);
-                               end = get_order_from_str(end_size);
+                               start = get_order_from_str(start_size, 
THP_ORDERS_ALL_ANON);
+                               end = get_order_from_str(end_size, 
THP_ORDERS_ALL_ANON);
                        } else {
-                               start = end = get_order_from_str(subtoken);
+                               start_size = end_size = subtoken;
+                               start = end = get_order_from_str(subtoken,
+                                                                
THP_ORDERS_ALL_ANON);
+                       }
+
+                       if (start == -EINVAL) {
+                               pr_err("invalid size %s in thp_anon boot 
parameter\n", start_size);
+                               goto err;
+                       }
+
+                       if (end == -EINVAL) {
+                               pr_err("invalid size %s in thp_anon boot 
parameter\n", end_size);
+                               goto err;
                        }
 
                        if (start < 0 || end < 0 || start > end)
diff --git a/mm/internal.h b/mm/internal.h
index d5b93c5b6364..5a7302baeed7 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1291,6 +1291,28 @@ static inline bool alloc_zeroed(void)
                        &init_on_alloc);
 }
 
+/*
+ * Parses a string with mem suffixes into its order. Useful to parse kernel
+ * parameters.
+ */
+static inline int get_order_from_str(const char *size_str,
+                                    unsigned long valid_orders)
+{
+       unsigned long size;
+       char *endptr;
+       int order;
+
+       size = memparse(size_str, &endptr);
+
+       if (!is_power_of_2(size))
+               return -EINVAL;
+       order = get_order(size);
+       if (BIT(order) & ~valid_orders)
+               return -EINVAL;
+
+       return order;
+}
+
 enum {
        /* mark page accessed */
        FOLL_TOUCH = 1 << 16,
-- 
2.46.2