[patch 1/2] mm: page_counter: pull "-1" handling out of page_counter_memparse()

[Johannes Weiner <hannes@cmpxchg.org>]

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>
---
 include/linux/page_counter.h | 3 ++-
 mm/hugetlb_cgroup.c          | 2 +-
 mm/memcontrol.c              | 4 ++--
 mm/page_counter.c            | 7 ++++---
 net/ipv4/tcp_memcontrol.c    | 2 +-
 5 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
index 955421575d16..17fa4f8de3a6 100644
--- a/include/linux/page_counter.h
+++ b/include/linux/page_counter.h
@@ -41,7 +41,8 @@ int page_counter_try_charge(struct page_counter *counter,
 			    struct page_counter **fail);
 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
 int page_counter_limit(struct page_counter *counter, unsigned long limit);
-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);
 
 static inline void page_counter_reset_watermark(struct page_counter *counter)
 {
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 05ad91cda22c..a3592a756ad9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3442,7 +3442,7 @@ 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;
 
@@ -3814,7 +3814,7 @@ 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;
 	}
diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index 272327134a1b..c2a75c6957a1 100644
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -120,7 +120,7 @@ static ssize_t tcp_cgroup_write(struct kernfs_open_file *of,
 	switch (of_cft(of)->private) {
 	case RES_LIMIT:
 		/* see memcontrol.c */
-		ret = page_counter_memparse(buf, &nr_pages);
+		ret = page_counter_memparse(buf, "-1", &nr_pages);
 		if (ret)
 			break;
 		mutex_lock(&tcp_limit_mutex);
-- 
2.2.0

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