From dbf52682cb02863d22b15e3742988c7c6e3f1710 Mon Sep 17 00:00:00 2001 From: Petr Mladek Date: Tue, 11 Oct 2016 13:55:50 -0700 Subject: [PATCH] kthread: better support freezable kthread workers This patch allows to make kthread worker freezable via a new @flags parameter. It will allow to avoid an init work in some kthreads. It currently does not affect the function of kthread_worker_fn() but it might help to do some optimization or fixes eventually. I currently do not know about any other use for the @flags parameter but I believe that we will want more flags in the future. Finally, I hope that it will not cause confusion with @flags member in struct kthread. Well, I guess that we will want to rework the basic kthreads implementation once all kthreads are converted into kthread workers or workqueues. It is possible that we will merge the two structures. Link: http://lkml.kernel.org/r/1470754545-17632-12-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek Acked-by: Tejun Heo Cc: Oleg Nesterov Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Steven Rostedt Cc: "Paul E. McKenney" Cc: Josh Triplett Cc: Thomas Gleixner Cc: Jiri Kosina Cc: Borislav Petkov Cc: Michal Hocko Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kthread.h | 12 +++++++++--- kernel/kthread.c | 21 +++++++++++++++------ 2 files changed, 24 insertions(+), 9 deletions(-) diff --git a/include/linux/kthread.h b/include/linux/kthread.h index 5c2ec2c4eb22..4f5235cb13bb 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -65,7 +65,12 @@ struct kthread_work; typedef void (*kthread_work_func_t)(struct kthread_work *work); void kthread_delayed_work_timer_fn(unsigned long __data); +enum { + KTW_FREEZABLE = 1 << 0, /* freeze during suspend */ +}; + struct kthread_worker { + unsigned int flags; spinlock_t lock; struct list_head work_list; struct list_head delayed_work_list; @@ -154,12 +159,13 @@ extern void __kthread_init_worker(struct kthread_worker *worker, int kthread_worker_fn(void *worker_ptr); -__printf(1, 2) +__printf(2, 3) struct kthread_worker * -kthread_create_worker(const char namefmt[], ...); +kthread_create_worker(unsigned int flags, const char namefmt[], ...); struct kthread_worker * -kthread_create_worker_on_cpu(int cpu, const char namefmt[], ...); +kthread_create_worker_on_cpu(int cpu, unsigned int flags, + const char namefmt[], ...); bool kthread_queue_work(struct kthread_worker *worker, struct kthread_work *work); diff --git a/kernel/kthread.c b/kernel/kthread.c index c1fcc63fa605..be2cc1f9dd57 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -560,11 +560,11 @@ void __kthread_init_worker(struct kthread_worker *worker, const char *name, struct lock_class_key *key) { + memset(worker, 0, sizeof(struct kthread_worker)); spin_lock_init(&worker->lock); lockdep_set_class_and_name(&worker->lock, key, name); INIT_LIST_HEAD(&worker->work_list); INIT_LIST_HEAD(&worker->delayed_work_list); - worker->task = NULL; } EXPORT_SYMBOL_GPL(__kthread_init_worker); @@ -594,6 +594,10 @@ int kthread_worker_fn(void *worker_ptr) */ WARN_ON(worker->task && worker->task != current); worker->task = current; + + if (worker->flags & KTW_FREEZABLE) + set_freezable(); + repeat: set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ @@ -627,7 +631,8 @@ repeat: EXPORT_SYMBOL_GPL(kthread_worker_fn); static struct kthread_worker * -__kthread_create_worker(int cpu, const char namefmt[], va_list args) +__kthread_create_worker(int cpu, unsigned int flags, + const char namefmt[], va_list args) { struct kthread_worker *worker; struct task_struct *task; @@ -657,6 +662,7 @@ __kthread_create_worker(int cpu, const char namefmt[], va_list args) if (IS_ERR(task)) goto fail_task; + worker->flags = flags; worker->task = task; wake_up_process(task); return worker; @@ -668,6 +674,7 @@ fail_task: /** * kthread_create_worker - create a kthread worker + * @flags: flags modifying the default behavior of the worker * @namefmt: printf-style name for the kthread worker (task). * * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) @@ -675,13 +682,13 @@ fail_task: * when the worker was SIGKILLed. */ struct kthread_worker * -kthread_create_worker(const char namefmt[], ...) +kthread_create_worker(unsigned int flags, const char namefmt[], ...) { struct kthread_worker *worker; va_list args; va_start(args, namefmt); - worker = __kthread_create_worker(-1, namefmt, args); + worker = __kthread_create_worker(-1, flags, namefmt, args); va_end(args); return worker; @@ -692,6 +699,7 @@ EXPORT_SYMBOL(kthread_create_worker); * kthread_create_worker_on_cpu - create a kthread worker and bind it * it to a given CPU and the associated NUMA node. * @cpu: CPU number + * @flags: flags modifying the default behavior of the worker * @namefmt: printf-style name for the kthread worker (task). * * Use a valid CPU number if you want to bind the kthread worker @@ -705,13 +713,14 @@ EXPORT_SYMBOL(kthread_create_worker); * when the worker was SIGKILLed. */ struct kthread_worker * -kthread_create_worker_on_cpu(int cpu, const char namefmt[], ...) +kthread_create_worker_on_cpu(int cpu, unsigned int flags, + const char namefmt[], ...) { struct kthread_worker *worker; va_list args; va_start(args, namefmt); - worker = __kthread_create_worker(cpu, namefmt, args); + worker = __kthread_create_worker(cpu, flags, namefmt, args); va_end(args); return worker; -- 2.20.1