mm: page_counter: pull "-1" handling out of page_counter_memparse()

The unified hierarchy interface for memory cgroups will no longer use "-1"
to mean maximum possible resource value.  In preparation for this, make
the string an argument and let the caller supply it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 7 insertions, 6 deletions

diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index 037e1c00a5b7..6e0057439a46 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -279,7 +279,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
                 return -EINVAL;
 
         buf = strstrip(buf);
-        ret = page_counter_memparse(buf, &nr_pages);
+        ret = page_counter_memparse(buf, "-1", &nr_pages);
         if (ret)
                 return ret;
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index dc5c4cd0afdf..6453ea5a27aa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3414,7 +3414,7 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
         int ret;
 
         buf = strstrip(buf);
-        ret = page_counter_memparse(buf, &nr_pages);
+        ret = page_counter_memparse(buf, "-1", &nr_pages);
         if (ret)
                 return ret;
 
@@ -3786,7 +3786,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
         unsigned long usage;
         int i, size, ret;
 
-        ret = page_counter_memparse(args, &threshold);
+        ret = page_counter_memparse(args, "-1", &threshold);
         if (ret)
                 return ret;
 
diff --git a/mm/page_counter.c b/mm/page_counter.c
index a009574fbba9..11b4beda14ba 100644
--- a/mm/page_counter.c
+++ b/mm/page_counter.c
@@ -166,18 +166,19 @@ int page_counter_limit(struct page_counter *counter, unsigned long limit)
 /**
  * page_counter_memparse - memparse() for page counter limits
  * @buf: string to parse
+ * @max: string meaning maximum possible value
  * @nr_pages: returns the result in number of pages
  *
  * Returns -EINVAL, or 0 and @nr_pages on success.  @nr_pages will be
  * limited to %PAGE_COUNTER_MAX.
  */
-int page_counter_memparse(const char *buf, unsigned long *nr_pages)
+int page_counter_memparse(const char *buf, const char *max,
+                          unsigned long *nr_pages)
 {
-        char unlimited[] = "-1";
         char *end;
         u64 bytes;
 
-        if (!strncmp(buf, unlimited, sizeof(unlimited))) {
+        if (!strcmp(buf, max)) {
                 *nr_pages = PAGE_COUNTER_MAX;
                 return 0;
         }