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Commit 3b13758f authored by Nina Schiff's avatar Nina Schiff Committed by David S. Miller
Browse files

cgroups: Allow dynamically changing net_classid 



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: default avatarNina Schiff <ninasc@fb.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fe761bcb

net/core/netclassid_cgroup.c

+18 −8
Original line number Diff line number Diff line
@@ -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 cgrp_attach(struct cgroup_subsys_state *css,

			struct cgroup_taskset *tset)

static void update_classid(struct cgroup_subsys_state *css, void *v)

{

	struct cgroup_cls_state *cs = css_cls_state(css);

	void *v = (void *)(unsigned long)cs->classid;

	struct css_task_iter it;

	struct task_struct *p;



	cgroup_taskset_for_each(p, tset) {

	css_task_iter_start(css, &it);

	while ((p = css_task_iter_next(&it))) {

		task_lock(p);

		iterate_fd(p->files, 0, update_classid, v);

		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)

{

	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;

}