On Wed 27-11-13 18:42:30, Tejun Heo wrote:
> 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@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Cc: Balbir Singh <bsingharora@xxxxxxxxx>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Thanks!
> ---
> mm/memcontrol.c | 49 +++++++++++++++++++++----------------------------
> 1 file changed, 21 insertions(+), 28 deletions(-)
>
> 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 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
> 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 @@ static ssize_t mem_cgroup_read(struct cgroup_subsys_state *css,
> 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 void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
> }
>
> 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 @@ static struct cftype mem_cgroup_files[] = {
> {
> .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 @@ static struct cftype mem_cgroup_files[] = {
> },
> {
> .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 @@ static struct cftype mem_cgroup_files[] = {
> .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 @@ static struct cftype memsw_cgroup_files[] = {
> {
> .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 */
> };
> --
> 1.8.4.2
>
--
Michal Hocko
SUSE Labs
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