evie/android_kernel_oneplus_msm8998
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cgroup: pids: kill pids_fork(), simplify pids_can_fork() and pids_cancel_fork()

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Now that we know that the forking task can't migrate amd the child is always
moved to the same cgroup by cgroup_post_fork()->css_set_move_task() we can
change pids_can_fork() and pids_cancel_fork() to just use task_css(current).
And since we no longer need to pin this css, we can remove pid_fork().

Note: the patch uses task_css_check(true), perhaps it makes sense to add a
helper or change task_css_set_check() to take cgroup_threadgroup_rwsem into
account.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Oleg Nesterov 2015-11-27 19:57:22 +01:00 • committed by Tejun Heo
parent c9e75f0492
commit afbcb364be
1 changed files with 10 additions and 31 deletions
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41
kernel/cgroup_pids.c
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@ -205,48 +205,28 @@ static void pids_cancel_attach(struct cgroup_subsys_state *css,
} }
} }
/*
* task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies
* on threadgroup_change_begin() held by the copy_process().
*/
static int pids_can_fork(struct task_struct *task, void **priv_p) static int pids_can_fork(struct task_struct *task, void **priv_p)
{ {
struct cgroup_subsys_state *css; struct cgroup_subsys_state *css;
struct pids_cgroup *pids; struct pids_cgroup *pids;
int err;
/* css = task_css_check(current, pids_cgrp_id, true);
* Use the "current" task_css for the pids subsystem as the tentative
* css. It is possible we will charge the wrong hierarchy, in which
* case we will forcefully revert/reapply the charge on the right
* hierarchy after it is committed to the task proper.
*/
css = task_get_css(current, pids_cgrp_id);
pids = css_pids(css); pids = css_pids(css);
return pids_try_charge(pids, 1);
err = pids_try_charge(pids, 1);
if (err)
goto err_css_put;
*priv_p = css;
return 0;
err_css_put:
css_put(css);
return err;
} }
static void pids_cancel_fork(struct task_struct *task, void *priv) static void pids_cancel_fork(struct task_struct *task, void *priv)
{ {
struct cgroup_subsys_state *css = priv; struct cgroup_subsys_state *css;
struct pids_cgroup *pids = css_pids(css); struct pids_cgroup *pids;
css = task_css_check(current, pids_cgrp_id, true);
pids = css_pids(css);
pids_uncharge(pids, 1); pids_uncharge(pids, 1);
css_put(css);
}
static void pids_fork(struct task_struct *task, void *priv)
{
struct cgroup_subsys_state *css = priv;
WARN_ON(task_css_check(task, pids_cgrp_id, true) != css);
css_put(css);
} }
static void pids_free(struct task_struct *task) static void pids_free(struct task_struct *task)
@ -329,7 +309,6 @@ struct cgroup_subsys pids_cgrp_subsys = {
.cancel_attach = pids_cancel_attach, .cancel_attach = pids_cancel_attach,
.can_fork = pids_can_fork, .can_fork = pids_can_fork,
.cancel_fork = pids_cancel_fork, .cancel_fork = pids_cancel_fork,
.fork = pids_fork,
.free = pids_free, .free = pids_free,
.legacy_cftypes = pids_files, .legacy_cftypes = pids_files,
.dfl_cftypes = pids_files, .dfl_cftypes = pids_files,