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cgroup: replace cftype->trigger() with cftype->write()
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cftype->trigger() is pointless.  It's trivial to ignore the input
buffer from a regular ->write() operation.  Convert all ->trigger()
users to ->write() and remove ->trigger().

This patch doesn't introduce any visible behavior changes.

Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Li Zefan <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
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@htejun
htejun committed May 13, 2014
1 parent 451af50 commit 6770c64
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Showing 5 changed files with 35 additions and 43 deletions.
8 changes: 0 additions & 8 deletions include/linux/cgroup.h
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Original file line number Diff line number Diff line change
Expand Up @@ -499,14 +499,6 @@ struct cftype {
int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
s64 val);

/*
* trigger() callback can be used to get some kick from the
* userspace, when the actual string written is not important
* at all. The private field can be used to determine the
* kick type for multiplexing.
*/
int (*trigger)(struct cgroup_subsys_state *css, unsigned int event);

/*
* write() is the generic write callback which maps directly to
* kernfs write operation and overrides all other operations.
Expand Down
5 changes: 1 addition & 4 deletions kernel/cgroup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1034,8 +1034,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft)
if (cft->read_u64 || cft->read_s64 || cft->seq_show)
mode |= S_IRUGO;

if (cft->write_u64 || cft->write_s64 || cft->write ||
cft->trigger)
if (cft->write_u64 || cft->write_s64 || cft->write)
mode |= S_IWUSR;

return mode;
Expand Down Expand Up @@ -2750,8 +2749,6 @@ static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
ret = kstrtoll(buf, 0, &v);
if (!ret)
ret = cft->write_s64(css, cft, v);
} else if (cft->trigger) {
ret = cft->trigger(css, (unsigned int)cft->private);
} else {
ret = -EINVAL;
}
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16 changes: 8 additions & 8 deletions mm/hugetlb_cgroup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -284,14 +284,14 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
return ret ?: nbytes;
}

static int hugetlb_cgroup_reset(struct cgroup_subsys_state *css,
unsigned int event)
static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
int idx, name, ret = 0;
struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));

idx = MEMFILE_IDX(event);
name = MEMFILE_ATTR(event);
idx = MEMFILE_IDX(of_cft(of)->private);
name = MEMFILE_ATTR(of_cft(of)->private);

switch (name) {
case RES_MAX_USAGE:
Expand All @@ -304,7 +304,7 @@ static int hugetlb_cgroup_reset(struct cgroup_subsys_state *css,
ret = -EINVAL;
break;
}
return ret;
return ret ?: nbytes;
}

static char *mem_fmt(char *buf, int size, unsigned long hsize)
Expand Down Expand Up @@ -344,14 +344,14 @@ static void __init __hugetlb_cgroup_file_init(int idx)
cft = &h->cgroup_files[2];
snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
cft->trigger = hugetlb_cgroup_reset;
cft->write = hugetlb_cgroup_reset;
cft->read_u64 = hugetlb_cgroup_read_u64;

/* Add the failcntfile */
cft = &h->cgroup_files[3];
snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
cft->private = MEMFILE_PRIVATE(idx, RES_FAILCNT);
cft->trigger = hugetlb_cgroup_reset;
cft->write = hugetlb_cgroup_reset;
cft->read_u64 = hugetlb_cgroup_read_u64;

/* NULL terminate the last cft */
Expand Down
34 changes: 18 additions & 16 deletions mm/memcontrol.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4887,14 +4887,15 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
return 0;
}

static int mem_cgroup_force_empty_write(struct cgroup_subsys_state *css,
unsigned int event)
static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of,
char *buf, size_t nbytes,
loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));

if (mem_cgroup_is_root(memcg))
return -EINVAL;
return mem_cgroup_force_empty(memcg);
return mem_cgroup_force_empty(memcg) ?: nbytes;
}

static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
Expand Down Expand Up @@ -5220,14 +5221,15 @@ static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
*memsw_limit = min_memsw_limit;
}

static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
int name;
enum res_type type;

type = MEMFILE_TYPE(event);
name = MEMFILE_ATTR(event);
type = MEMFILE_TYPE(of_cft(of)->private);
name = MEMFILE_ATTR(of_cft(of)->private);

switch (name) {
case RES_MAX_USAGE:
Expand All @@ -5252,7 +5254,7 @@ static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
break;
}

return 0;
return nbytes;
}

static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
Expand Down Expand Up @@ -6105,7 +6107,7 @@ static struct cftype mem_cgroup_files[] = {
{
.name = "max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
Expand All @@ -6123,7 +6125,7 @@ static struct cftype mem_cgroup_files[] = {
{
.name = "failcnt",
.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
Expand All @@ -6132,7 +6134,7 @@ static struct cftype mem_cgroup_files[] = {
},
{
.name = "force_empty",
.trigger = mem_cgroup_force_empty_write,
.write = mem_cgroup_force_empty_write,
},
{
.name = "use_hierarchy",
Expand Down Expand Up @@ -6186,13 +6188,13 @@ static struct cftype mem_cgroup_files[] = {
{
.name = "kmem.failcnt",
.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
.name = "kmem.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
#ifdef CONFIG_SLABINFO
Expand All @@ -6215,7 +6217,7 @@ static struct cftype memsw_cgroup_files[] = {
{
.name = "memsw.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{
Expand All @@ -6227,7 +6229,7 @@ static struct cftype memsw_cgroup_files[] = {
{
.name = "memsw.failcnt",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
.trigger = mem_cgroup_reset,
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
{ }, /* terminate */
Expand Down
15 changes: 8 additions & 7 deletions net/ipv4/tcp_memcontrol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -170,17 +170,18 @@ static u64 tcp_cgroup_read(struct cgroup_subsys_state *css, struct cftype *cft)
return val;
}

static int tcp_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
static ssize_t tcp_cgroup_reset(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg;
struct cg_proto *cg_proto;

memcg = mem_cgroup_from_css(css);
memcg = mem_cgroup_from_css(of_css(of));
cg_proto = tcp_prot.proto_cgroup(memcg);
if (!cg_proto)
return 0;
return nbytes;

switch (event) {
switch (of_cft(of)->private) {
case RES_MAX_USAGE:
res_counter_reset_max(&cg_proto->memory_allocated);
break;
Expand All @@ -189,7 +190,7 @@ static int tcp_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
break;
}

return 0;
return nbytes;
}

static struct cftype tcp_files[] = {
Expand All @@ -207,13 +208,13 @@ static struct cftype tcp_files[] = {
{
.name = "kmem.tcp.failcnt",
.private = RES_FAILCNT,
.trigger = tcp_cgroup_reset,
.write = tcp_cgroup_reset,
.read_u64 = tcp_cgroup_read,
},
{
.name = "kmem.tcp.max_usage_in_bytes",
.private = RES_MAX_USAGE,
.trigger = tcp_cgroup_reset,
.write = tcp_cgroup_reset,
.read_u64 = tcp_cgroup_read,
},
{ } /* terminate */
Expand Down

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