From 3b13758f51de30618d9c7f3fc174d8d1a3cb13cd Mon Sep 17 00:00:00 2001 From: Nina Schiff Date: Fri, 20 Nov 2015 12:31:39 -0800 Subject: [PATCH] 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: Nina Schiff Acked-by: Tejun Heo Signed-off-by: David S. Miller --- net/core/netclassid_cgroup.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/net/core/netclassid_cgroup.c b/net/core/netclassid_cgroup.c index 6441f47b1a8f..2e4df84c34a1 100644 --- a/net/core/netclassid_cgroup.c +++ b/net/core/netclassid_cgroup.c @@ -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; }