diff options
Diffstat (limited to 'include/linux/cgroup-defs.h')
| -rw-r--r-- | include/linux/cgroup-defs.h | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 06b77f9dd3f2..e5f4164cbd99 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -231,6 +231,14 @@ struct cgroup { int id; /* + * The depth this cgroup is at. The root is at depth zero and each + * step down the hierarchy increments the level. This along with + * ancestor_ids[] can determine whether a given cgroup is a + * descendant of another without traversing the hierarchy. + */ + int level; + + /* * Each non-empty css_set associated with this cgroup contributes * one to populated_cnt. All children with non-zero popuplated_cnt * of their own contribute one. The count is zero iff there's no @@ -285,6 +293,9 @@ struct cgroup { /* used to schedule release agent */ struct work_struct release_agent_work; + + /* ids of the ancestors at each level including self */ + int ancestor_ids[]; }; /* @@ -304,6 +315,9 @@ struct cgroup_root { /* The root cgroup. Root is destroyed on its release. */ struct cgroup cgrp; + /* for cgrp->ancestor_ids[0] */ + int cgrp_ancestor_id_storage; + /* Number of cgroups in the hierarchy, used only for /proc/cgroups */ atomic_t nr_cgrps; @@ -521,4 +535,116 @@ static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {} #endif /* CONFIG_CGROUPS */ +#ifdef CONFIG_SOCK_CGROUP_DATA + +/* + * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains + * per-socket cgroup information except for memcg association. + * + * On legacy hierarchies, net_prio and net_cls controllers directly set + * attributes on each sock which can then be tested by the network layer. + * On the default hierarchy, each sock is associated with the cgroup it was + * created in and the networking layer can match the cgroup directly. + * + * To avoid carrying all three cgroup related fields separately in sock, + * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer. + * On boot, sock_cgroup_data records the cgroup that the sock was created + * in so that cgroup2 matches can be made; however, once either net_prio or + * net_cls starts being used, the area is overriden to carry prioidx and/or + * classid. The two modes are distinguished by whether the lowest bit is + * set. Clear bit indicates cgroup pointer while set bit prioidx and + * classid. + * + * While userland may start using net_prio or net_cls at any time, once + * either is used, cgroup2 matching no longer works. There is no reason to + * mix the two and this is in line with how legacy and v2 compatibility is + * handled. On mode switch, cgroup references which are already being + * pointed to by socks may be leaked. While this can be remedied by adding + * synchronization around sock_cgroup_data, given that the number of leaked + * cgroups is bound and highly unlikely to be high, this seems to be the + * better trade-off. + */ +struct sock_cgroup_data { + union { +#ifdef __LITTLE_ENDIAN + struct { + u8 is_data; + u8 padding; + u16 prioidx; + u32 classid; + } __packed; +#else + struct { + u32 classid; + u16 prioidx; + u8 padding; + u8 is_data; + } __packed; +#endif + u64 val; + }; +}; + +/* + * There's a theoretical window where the following accessors race with + * updaters and return part of the previous pointer as the prioidx or + * classid. Such races are short-lived and the result isn't critical. + */ +static inline u16 sock_cgroup_prioidx(struct sock_cgroup_data *skcd) +{ + /* fallback to 1 which is always the ID of the root cgroup */ + return (skcd->is_data & 1) ? skcd->prioidx : 1; +} + +static inline u32 sock_cgroup_classid(struct sock_cgroup_data *skcd) +{ + /* fallback to 0 which is the unconfigured default classid */ + return (skcd->is_data & 1) ? skcd->classid : 0; +} + +/* + * If invoked concurrently, the updaters may clobber each other. The + * caller is responsible for synchronization. + */ +static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd, + u16 prioidx) +{ + struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; + + if (sock_cgroup_prioidx(&skcd_buf) == prioidx) + return; + + if (!(skcd_buf.is_data & 1)) { + skcd_buf.val = 0; + skcd_buf.is_data = 1; + } + + skcd_buf.prioidx = prioidx; + WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ +} + +static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd, + u32 classid) +{ + struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; + + if (sock_cgroup_classid(&skcd_buf) == classid) + return; + + if (!(skcd_buf.is_data & 1)) { + skcd_buf.val = 0; + skcd_buf.is_data = 1; + } + + skcd_buf.classid = classid; + WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ +} + +#else /* CONFIG_SOCK_CGROUP_DATA */ + +struct sock_cgroup_data { +}; + +#endif /* CONFIG_SOCK_CGROUP_DATA */ + #endif /* _LINUX_CGROUP_DEFS_H */ |