From 9db8de3722d184b8a431afd6bef803d6867ac889 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 13 Feb 2014 06:58:43 -0500 Subject: [PATCH] cgroup: cosmetic updates to cgroup_attach_task() cgroup_attach_task() is planned to go through restructuring. Let's tidy it up a bit in preparation. * Update cgroup_attach_task() to receive the target task argument in @leader instead of @tsk. * Rename @tsk to @task. * Rename @retval to @ret. This is purely cosmetic. v2: get_nr_threads() was using uninitialized @task instead of @leader. Fixed. Reported by Dan Carpenter. Signed-off-by: Tejun Heo Acked-by: Li Zefan Cc: Dan Carpenter --- kernel/cgroup.c | 45 +++++++++++++++++++++++---------------------- 1 file changed, 23 insertions(+), 22 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index a9d9bbb12310..9a890a2e58fc 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1728,20 +1728,20 @@ static void cgroup_task_migrate(struct cgroup *old_cgrp, /** * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup * @cgrp: the cgroup to attach to - * @tsk: the task or the leader of the threadgroup to be attached + * @leader: the task or the leader of the threadgroup to be attached * @threadgroup: attach the whole threadgroup? * * Call holding cgroup_mutex and the group_rwsem of the leader. Will take * task_lock of @tsk or each thread in the threadgroup individually in turn. */ -static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, +static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *leader, bool threadgroup) { - int retval, i, group_size; + int ret, i, group_size; struct cgroupfs_root *root = cgrp->root; struct cgroup_subsys_state *css, *failed_css = NULL; /* threadgroup list cursor and array */ - struct task_struct *leader = tsk; + struct task_struct *task; struct task_and_cgroup *tc; struct flex_array *group; struct cgroup_taskset tset = { }; @@ -1754,7 +1754,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, * threads exit, this will just be an over-estimate. */ if (threadgroup) - group_size = get_nr_threads(tsk); + group_size = get_nr_threads(leader); else group_size = 1; /* flex_array supports very large thread-groups better than kmalloc. */ @@ -1762,8 +1762,8 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, if (!group) return -ENOMEM; /* pre-allocate to guarantee space while iterating in rcu read-side. */ - retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); - if (retval) + ret = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); + if (ret) goto out_free_group_list; i = 0; @@ -1774,17 +1774,18 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, */ down_read(&css_set_rwsem); rcu_read_lock(); + task = leader; do { struct task_and_cgroup ent; - /* @tsk either already exited or can't exit until the end */ - if (tsk->flags & PF_EXITING) + /* @task either already exited or can't exit until the end */ + if (task->flags & PF_EXITING) goto next; /* as per above, nr_threads may decrease, but not increase. */ BUG_ON(i >= group_size); - ent.task = tsk; - ent.cgrp = task_cgroup_from_root(tsk, root); + ent.task = task; + ent.cgrp = task_cgroup_from_root(task, root); /* nothing to do if this task is already in the cgroup */ if (ent.cgrp == cgrp) goto next; @@ -1792,13 +1793,13 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, * saying GFP_ATOMIC has no effect here because we did prealloc * earlier, but it's good form to communicate our expectations. */ - retval = flex_array_put(group, i, &ent, GFP_ATOMIC); - BUG_ON(retval != 0); + ret = flex_array_put(group, i, &ent, GFP_ATOMIC); + BUG_ON(ret != 0); i++; next: if (!threadgroup) break; - } while_each_thread(leader, tsk); + } while_each_thread(leader, task); rcu_read_unlock(); up_read(&css_set_rwsem); /* remember the number of threads in the array for later. */ @@ -1807,7 +1808,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, tset.tc_array_len = group_size; /* methods shouldn't be called if no task is actually migrating */ - retval = 0; + ret = 0; if (!group_size) goto out_free_group_list; @@ -1816,8 +1817,8 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, */ for_each_css(css, i, cgrp) { if (css->ss->can_attach) { - retval = css->ss->can_attach(css, &tset); - if (retval) { + ret = css->ss->can_attach(css, &tset); + if (ret) { failed_css = css; goto out_cancel_attach; } @@ -1835,7 +1836,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, old_cset = task_css_set(tc->task); tc->cset = find_css_set(old_cset, cgrp); if (!tc->cset) { - retval = -ENOMEM; + ret = -ENOMEM; goto out_put_css_set_refs; } } @@ -1863,9 +1864,9 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, /* * step 5: success! and cleanup */ - retval = 0; + ret = 0; out_put_css_set_refs: - if (retval) { + if (ret) { for (i = 0; i < group_size; i++) { tc = flex_array_get(group, i); if (!tc->cset) @@ -1874,7 +1875,7 @@ out_put_css_set_refs: } } out_cancel_attach: - if (retval) { + if (ret) { for_each_css(css, i, cgrp) { if (css == failed_css) break; @@ -1884,7 +1885,7 @@ out_cancel_attach: } out_free_group_list: flex_array_free(group); - return retval; + return ret; } /* -- 2.39.2