/* * Xen stolen ticks accounting. */ #include #include #include #include #include #include #include #include #include #include #include #include /* runstate info updated by Xen */ static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate); /* return an consistent snapshot of 64-bit time/counter value */ static u64 get64(const u64 *p) { u64 ret; if (BITS_PER_LONG < 64) { u32 *p32 = (u32 *)p; u32 h, l, h2; /* * Read high then low, and then make sure high is * still the same; this will only loop if low wraps * and carries into high. * XXX some clean way to make this endian-proof? */ do { h = READ_ONCE(p32[1]); l = READ_ONCE(p32[0]); h2 = READ_ONCE(p32[1]); } while(h2 != h); ret = (((u64)h) << 32) | l; } else ret = READ_ONCE(*p); return ret; } static void xen_get_runstate_snapshot_cpu(struct vcpu_runstate_info *res, unsigned int cpu) { u64 state_time; struct vcpu_runstate_info *state; BUG_ON(preemptible()); state = per_cpu_ptr(&xen_runstate, cpu); do { state_time = get64(&state->state_entry_time); rmb(); /* Hypervisor might update data. */ *res = READ_ONCE(*state); rmb(); /* Hypervisor might update data. */ } while (get64(&state->state_entry_time) != state_time || (state_time & XEN_RUNSTATE_UPDATE)); } /* * Runstate accounting */ void xen_get_runstate_snapshot(struct vcpu_runstate_info *res) { xen_get_runstate_snapshot_cpu(res, smp_processor_id()); } /* return true when a vcpu could run but has no real cpu to run on */ bool xen_vcpu_stolen(int vcpu) { return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable; } u64 xen_steal_clock(int cpu) { struct vcpu_runstate_info state; xen_get_runstate_snapshot_cpu(&state, cpu); return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline]; } void xen_setup_runstate_info(int cpu) { struct vcpu_register_runstate_memory_area area; area.addr.v = &per_cpu(xen_runstate, cpu); if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, xen_vcpu_nr(cpu), &area)) BUG(); } void __init xen_time_setup_guest(void) { bool xen_runstate_remote; xen_runstate_remote = !HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_runstate_update_flag); pv_time_ops.steal_clock = xen_steal_clock; static_key_slow_inc(¶virt_steal_enabled); if (xen_runstate_remote) static_key_slow_inc(¶virt_steal_rq_enabled); } commit/?id=07cd12945551b63ecb1a349d50a6d69d1d6feb4a'>root/include
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authorTejun Heo <tj@kernel.org>2017-01-26 16:47:28 -0500
committerTejun Heo <tj@kernel.org>2017-01-26 16:47:28 -0500
commit07cd12945551b63ecb1a349d50a6d69d1d6feb4a (patch)
tree75f65eba7eac9277971082a2d5a4cf1370562c0c /include
parent7ce7d89f48834cefece7804d38fc5d85382edf77 (diff)
cgroup: don't online subsystems before cgroup_name/path() are operational
While refactoring cgroup creation, a5bca2152036 ("cgroup: factor out cgroup_create() out of cgroup_mkdir()") incorrectly onlined subsystems before the new cgroup is associated with it kernfs_node. This is fine for cgroup proper but cgroup_name/path() depend on the associated kernfs_node and if a subsystem makes the new cgroup_subsys_state visible, which they're allowed to after onlining, it can lead to NULL dereference. The current code performs cgroup creation and subsystem onlining in cgroup_create() and cgroup_mkdir() makes the cgroup and subsystems visible afterwards. There's no reason to online the subsystems early and we can simply drop cgroup_apply_control_enable() call from cgroup_create() so that the subsystems are onlined and made visible at the same time. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Fixes: a5bca2152036 ("cgroup: factor out cgroup_create() out of cgroup_mkdir()") Cc: stable@vger.kernel.org # v4.6+
Diffstat (limited to 'include')