cgroup: replace cftype->write_string() with cftype->write()
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>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a16f91d..2a88ce7 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1035,7 +1035,7 @@
mode |= S_IRUGO;
if (cft->write_u64 || cft->write_s64 || cft->write ||
- cft->write_string || cft->trigger)
+ cft->trigger)
mode |= S_IWUSR;
return mode;
@@ -2352,20 +2352,21 @@
return attach_task_by_pid(css->cgroup, tgid, true);
}
-static int cgroup_release_agent_write(struct cgroup_subsys_state *css,
- struct cftype *cft, char *buffer)
+static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
{
- struct cgroup_root *root = css->cgroup->root;
+ struct cgroup *cgrp = of_css(of)->cgroup;
+ struct cgroup_root *root = cgrp->root;
BUILD_BUG_ON(sizeof(root->release_agent_path) < PATH_MAX);
- if (!cgroup_lock_live_group(css->cgroup))
+ if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
spin_lock(&release_agent_path_lock);
- strlcpy(root->release_agent_path, buffer,
+ strlcpy(root->release_agent_path, strstrip(buf),
sizeof(root->release_agent_path));
spin_unlock(&release_agent_path_lock);
mutex_unlock(&cgroup_mutex);
- return 0;
+ return nbytes;
}
static int cgroup_release_agent_show(struct seq_file *seq, void *v)
@@ -2530,21 +2531,22 @@
}
/* change the enabled child controllers for a cgroup in the default hierarchy */
-static int cgroup_subtree_control_write(struct cgroup_subsys_state *dummy_css,
- struct cftype *cft, char *buffer)
+static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
{
unsigned int enable = 0, disable = 0;
- struct cgroup *cgrp = dummy_css->cgroup, *child;
+ struct cgroup *cgrp = of_css(of)->cgroup, *child;
struct cgroup_subsys *ss;
- char *tok, *p;
+ char *tok;
int ssid, ret;
/*
* Parse input - space separated list of subsystem names prefixed
* with either + or -.
*/
- p = buffer;
- while ((tok = strsep(&p, " "))) {
+ buf = strstrip(buf);
+ while ((tok = strsep(&buf, " "))) {
if (tok[0] == '\0')
continue;
for_each_subsys(ss, ssid) {
@@ -2692,7 +2694,7 @@
out_unbreak:
kernfs_unbreak_active_protection(cgrp->control_kn);
cgroup_put(cgrp);
- return ret;
+ return ret ?: nbytes;
err_undo_css:
cgrp->child_subsys_mask &= ~enable;
@@ -2738,9 +2740,7 @@
css = cgroup_css(cgrp, cft->ss);
rcu_read_unlock();
- if (cft->write_string) {
- ret = cft->write_string(css, cft, strstrip(buf));
- } else if (cft->write_u64) {
+ if (cft->write_u64) {
unsigned long long v;
ret = kstrtoull(buf, 0, &v);
if (!ret)
@@ -3984,7 +3984,7 @@
.name = "cgroup.subtree_control",
.flags = CFTYPE_ONLY_ON_DFL,
.seq_show = cgroup_subtree_control_show,
- .write_string = cgroup_subtree_control_write,
+ .write = cgroup_subtree_control_write,
},
{
.name = "cgroup.populated",
@@ -4018,7 +4018,7 @@
.name = "release_agent",
.flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
.seq_show = cgroup_release_agent_show,
- .write_string = cgroup_release_agent_write,
+ .write = cgroup_release_agent_write,
.max_write_len = PATH_MAX - 1,
},
{ } /* terminate */