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cgroup: replace cftype->write_string() with cftype->write()

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Convert all cftype->write_string() users to the new cftype->write()
which maps directly to kernfs write operation and has full access to
kernfs and cgroup contexts.  The conversions are mostly mechanical.

* @css and @cft are accessed using of_css() and of_cft() accessors
  respectively instead of being specified as arguments.

* Should return @nbytes on success instead of 0.

* @buf is not trimmed automatically.  Trim if necessary.  Note that
  blkcg and netprio don't need this as the parsers already handle
  whitespaces.

cftype->write_string() has no user left after the conversions and
removed.

While at it, remove unnecessary local variable @p in
cgroup_subtree_control_write() and stale comment about
CGROUP_LOCAL_BUFFER_SIZE in cgroup_freezer.c.

This patch doesn't introduce any visible behavior changes.

v2: netprio was missing from conversion.  Converted.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: "David S. Miller" <davem@davemloft.net>
This commit is contained in:
Tejun Heo 2014-05-13 12:16:21 -04:00
parent b41686401e
commit 451af504df
11 changed files with 124 additions and 125 deletions
Download patch file Download diff file Expand all files Collapse all files

20
kernel/cgroup_freezer.c
View file

@ -73,10 +73,6 @@ bool cgroup_freezing(struct task_struct *task)
return ret;
}
/*
* cgroups_write_string() limits the size of freezer state strings to
* CGROUP_LOCAL_BUFFER_SIZE
*/
static const char *freezer_state_strs(unsigned int state)
{
if (state & CGROUP_FROZEN)
@ -423,20 +419,22 @@ static void freezer_change_state(struct freezer *freezer, bool freeze)
mutex_unlock(&freezer_mutex);
}
static int freezer_write(struct cgroup_subsys_state *css, struct cftype *cft,
char *buffer)
static ssize_t freezer_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
bool freeze;
if (strcmp(buffer, freezer_state_strs(0)) == 0)
buf = strstrip(buf);
if (strcmp(buf, freezer_state_strs(0)) == 0)
freeze = false;
else if (strcmp(buffer, freezer_state_strs(CGROUP_FROZEN)) == 0)
else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0)
freeze = true;
else
return -EINVAL;
freezer_change_state(css_freezer(css), freeze);
return 0;
freezer_change_state(css_freezer(of_css(of)), freeze);
return nbytes;
}
static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css,
@ -460,7 +458,7 @@ static struct cftype files[] = {
.name = "state",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = freezer_read,
.write_string = freezer_write,
.write = freezer_write,
},
{
.name = "self_freezing",