diff --git a/include/linux/kthread.h b/include/linux/kthread.h index 82e197eeac91..bd4369c83dfb 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -3,6 +3,7 @@ /* Simple interface for creating and stopping kernel threads without mess. */ #include #include +#include __printf(4, 5) struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), @@ -198,4 +199,14 @@ bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *work); void kthread_destroy_worker(struct kthread_worker *worker); +#ifdef CONFIG_CGROUPS +void kthread_associate_blkcg(struct cgroup_subsys_state *css); +struct cgroup_subsys_state *kthread_blkcg(void); +#else +static inline void kthread_associate_blkcg(struct cgroup_subsys_state *css) { } +static inline struct cgroup_subsys_state *kthread_blkcg(void) +{ + return NULL; +} +#endif #endif /* _LINUX_KTHREAD_H */ diff --git a/kernel/kthread.c b/kernel/kthread.c index 1c19edf82427..b011ea08967f 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -20,7 +20,6 @@ #include #include #include -#include #include static DEFINE_SPINLOCK(kthread_create_lock); @@ -47,6 +46,9 @@ struct kthread { void *data; struct completion parked; struct completion exited; +#ifdef CONFIG_CGROUPS + struct cgroup_subsys_state *blkcg_css; +#endif }; enum KTHREAD_BITS { @@ -74,11 +76,17 @@ static inline struct kthread *to_kthread(struct task_struct *k) void free_kthread_struct(struct task_struct *k) { + struct kthread *kthread; + /* * Can be NULL if this kthread was created by kernel_thread() * or if kmalloc() in kthread() failed. */ - kfree(to_kthread(k)); + kthread = to_kthread(k); +#ifdef CONFIG_CGROUPS + WARN_ON_ONCE(kthread && kthread->blkcg_css); +#endif + kfree(kthread); } /** @@ -216,6 +224,9 @@ static int kthread(void *_create) self->data = data; init_completion(&self->exited); init_completion(&self->parked); +#ifdef CONFIG_CGROUPS + self->blkcg_css = NULL; +#endif current->vfork_done = &self->exited; /* OK, tell user we're spawned, wait for stop or wakeup */ @@ -1154,3 +1165,54 @@ void kthread_destroy_worker(struct kthread_worker *worker) kfree(worker); } EXPORT_SYMBOL(kthread_destroy_worker); + +#ifdef CONFIG_CGROUPS +/** + * kthread_associate_blkcg - associate blkcg to current kthread + * @css: the cgroup info + * + * Current thread must be a kthread. The thread is running jobs on behalf of + * other threads. In some cases, we expect the jobs attach cgroup info of + * original threads instead of that of current thread. This function stores + * original thread's cgroup info in current kthread context for later + * retrieval. + */ +void kthread_associate_blkcg(struct cgroup_subsys_state *css) +{ + struct kthread *kthread; + + if (!(current->flags & PF_KTHREAD)) + return; + kthread = to_kthread(current); + if (!kthread) + return; + + if (kthread->blkcg_css) { + css_put(kthread->blkcg_css); + kthread->blkcg_css = NULL; + } + if (css) { + css_get(css); + kthread->blkcg_css = css; + } +} +EXPORT_SYMBOL(kthread_associate_blkcg); + +/** + * kthread_blkcg - get associated blkcg css of current kthread + * + * Current thread must be a kthread. + */ +struct cgroup_subsys_state *kthread_blkcg(void) +{ + struct kthread *kthread; + + if (current->flags & PF_KTHREAD) { + kthread = to_kthread(current); + if (kthread) + return kthread->blkcg_css; + } + return NULL; +} +EXPORT_SYMBOL(kthread_blkcg); +#endif