From acbef755f40e204b8a6503fa79958d51a898762a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 May 2014 12:16:22 -0400 Subject: [PATCH] cgroup: convert "tasks" and "cgroup.procs" handle to use cftype->write() cgroup_tasks_write() and cgroup_procs_write() are currently using cftype->write_u64(). This patch converts them to use cftype->write() instead. This allows access to the associated kernfs_open_file which will be necessary to implement the planned kernfs active protection manipulation for these files. This shifts buffer parsing to attach_task_by_pid() and makes it return @nbytes on success. Let's rename it to __cgroup_procs_write() to clearly indicate that this is a write handler implementation. This patch doesn't introduce any visible behavior changes. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- kernel/cgroup.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2f16aab03493..9a48c117ebf1 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2232,12 +2232,18 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp, * function to attach either it or all tasks in its threadgroup. Will lock * cgroup_mutex and threadgroup. */ -static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) +static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, + size_t nbytes, loff_t off, bool threadgroup) { struct task_struct *tsk; const struct cred *cred = current_cred(), *tcred; + struct cgroup *cgrp = of_css(of)->cgroup; + pid_t pid; int ret; + if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) + return -EINVAL; + if (!cgroup_lock_live_group(cgrp)) return -ENODEV; @@ -2305,7 +2311,7 @@ retry_find_task: put_task_struct(tsk); out_unlock_cgroup: mutex_unlock(&cgroup_mutex); - return ret; + return ret ?: nbytes; } /** @@ -2339,16 +2345,16 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) } EXPORT_SYMBOL_GPL(cgroup_attach_task_all); -static int cgroup_tasks_write(struct cgroup_subsys_state *css, - struct cftype *cft, u64 pid) +static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) { - return attach_task_by_pid(css->cgroup, pid, false); + return __cgroup_procs_write(of, buf, nbytes, off, false); } -static int cgroup_procs_write(struct cgroup_subsys_state *css, - struct cftype *cft, u64 tgid) +static ssize_t cgroup_procs_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) { - return attach_task_by_pid(css->cgroup, tgid, true); + return __cgroup_procs_write(of, buf, nbytes, off, true); } static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, @@ -3953,7 +3959,7 @@ static struct cftype cgroup_base_files[] = { .seq_stop = cgroup_pidlist_stop, .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_PROCS, - .write_u64 = cgroup_procs_write, + .write = cgroup_procs_write, .mode = S_IRUGO | S_IWUSR, }, { @@ -4002,7 +4008,7 @@ static struct cftype cgroup_base_files[] = { .seq_stop = cgroup_pidlist_stop, .seq_show = cgroup_pidlist_show, .private = CGROUP_FILE_TASKS, - .write_u64 = cgroup_tasks_write, + .write = cgroup_tasks_write, .mode = S_IRUGO | S_IWUSR, }, {