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cgroups: Allow dynamically changing net_classid

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The classid of a process is changed either when a process is moved to
or from a cgroup or when the net_cls.classid file is updated.
Previously net_cls only supported propogating these changes to the
cgroup's related sockets when a process was added or removed from the
cgroup. This means it was neccessary to remove and re-add all processes
to a cgroup in order to update its classid. This change introduces
support for doing this dynamically - i.e. when the value is changed in
the net_cls_classid file, this will also trigger an update to the
classid associated with all sockets controlled by the cgroup.
This mimics the behaviour of other cgroup subsystems.
net_prio circumvents this issue by storing an index into a table with
each socket (and so any updates to the table, don't require updating
the value associated with the socket). net_cls, however, passes the
socket the classid directly, and so this additional step is needed.

Signed-off-by: Nina Schiff <ninasc@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nina Schiff 2015-11-20 12:31:39 -08:00 committed by David S. Miller
parent fe761bcb90
commit 3b13758f51
1 changed files with 21 additions and 11 deletions
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32
net/core/netclassid_cgroup.c
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@ -56,7 +56,7 @@ static void cgrp_css_free(struct cgroup_subsys_state *css)
kfree(css_cls_state(css));
}
static int update_classid(const void *v, struct file *file, unsigned n)
static int update_classid_sock(const void *v, struct file *file, unsigned n)
{
int err;
struct socket *sock = sock_from_file(file, &err);
@ -67,18 +67,25 @@ static int update_classid(const void *v, struct file *file, unsigned n)
return 0;
}
static void update_classid(struct cgroup_subsys_state *css, void *v)
{
struct css_task_iter it;
struct task_struct *p;
css_task_iter_start(css, &it);
while ((p = css_task_iter_next(&it))) {
task_lock(p);
iterate_fd(p->files, 0, update_classid_sock, v);
task_unlock(p);
}
css_task_iter_end(&it);
}
static void cgrp_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
struct cgroup_cls_state *cs = css_cls_state(css);
void *v = (void *)(unsigned long)cs->classid;
struct task_struct *p;
cgroup_taskset_for_each(p, tset) {
task_lock(p);
iterate_fd(p->files, 0, update_classid, v);
task_unlock(p);
}
update_classid(css,
(void *)(unsigned long)css_cls_state(css)->classid);
}
static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
@ -89,8 +96,11 @@ static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
u64 value)
{
css_cls_state(css)->classid = (u32) value;
struct cgroup_cls_state *cs = css_cls_state(css);
cs->classid = (u32)value;
update_classid(css, (void *)(unsigned long)cs->classid);
return 0;
}