memcg: convert away from cftype->read() and ->read_map()
In preparation of conversion to kernfs, cgroup file handling is being
consolidated so that it can be easily mapped to the seq_file based
interface of kernfs.
cftype->read_map() doesn't add any value and being replaced with
->read_seq_string(), and all users of cftype->read() can be easily
served, usually better, by seq_file and other methods.
Update mem_cgroup_read() to return u64 instead of printing itself and
rename it to mem_cgroup_read_u64(), and update
mem_cgroup_oom_control_read() to use ->read_seq_string() instead of
->read_map().
This patch doesn't make any visible behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7aa0d40..f149521 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5150,14 +5150,12 @@
return val << PAGE_SHIFT;
}
-static ssize_t mem_cgroup_read(struct cgroup_subsys_state *css,
- struct cftype *cft, struct file *file,
- char __user *buf, size_t nbytes, loff_t *ppos)
+static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
+ struct cftype *cft)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
- char str[64];
u64 val;
- int name, len;
+ int name;
enum res_type type;
type = MEMFILE_TYPE(cft->private);
@@ -5183,8 +5181,7 @@
BUG();
}
- len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
- return simple_read_from_buffer(buf, nbytes, ppos, str, len);
+ return val;
}
static int memcg_update_kmem_limit(struct cgroup_subsys_state *css, u64 val)
@@ -5911,16 +5908,12 @@
}
static int mem_cgroup_oom_control_read(struct cgroup_subsys_state *css,
- struct cftype *cft, struct cgroup_map_cb *cb)
+ struct cftype *cft, struct seq_file *sf)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
- cb->fill(cb, "oom_kill_disable", memcg->oom_kill_disable);
-
- if (atomic_read(&memcg->under_oom))
- cb->fill(cb, "under_oom", 1);
- else
- cb->fill(cb, "under_oom", 0);
+ seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);
+ seq_printf(sf, "under_oom %d\n", (bool)atomic_read(&memcg->under_oom));
return 0;
}
@@ -6239,31 +6232,31 @@
{
.name = "usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
.write_string = mem_cgroup_write,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "soft_limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
.write_string = mem_cgroup_write,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "failcnt",
.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "stat",
@@ -6297,7 +6290,7 @@
},
{
.name = "oom_control",
- .read_map = mem_cgroup_oom_control_read,
+ .read_seq_string = mem_cgroup_oom_control_read,
.write_u64 = mem_cgroup_oom_control_write,
.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
},
@@ -6315,24 +6308,24 @@
.name = "kmem.limit_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
.write_string = mem_cgroup_write,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.usage_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.failcnt",
.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
#ifdef CONFIG_SLABINFO
{
@@ -6349,25 +6342,25 @@
{
.name = "memsw.usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
.write_string = mem_cgroup_write,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{
.name = "memsw.failcnt",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
.trigger = mem_cgroup_reset,
- .read = mem_cgroup_read,
+ .read_u64 = mem_cgroup_read_u64,
},
{ }, /* terminate */
};