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Date: Sun, 16 Aug 2020 23:32:35 +0800 From: qianli zhao <zhaoqianligood@...il.com> To: Stephen Boyd <sboyd@...nel.org> Cc: Felix.Kuehling@....com, akpm@...ux-foundation.org, axboe@...nel.dk, Thomas Gleixner <tglx@...utronix.de>, John Stultz <john.stultz@...aro.org>, ben.dooks@...ethink.co.uk, bfields@...hat.com, cl@...k-chips.com, linux-kernel@...r.kernel.org, zhaoqianli@...omi.com Subject: Re: [PATCH v3] kthread: add objectdebug support Hi,Stephen Thanks for your suggestion, i will improve my patch. Thanks. On Sat, Aug 15, 2020 at 4:18 PM Stephen Boyd <sboyd@...nel.org> wrote: > > Quoting Qianli Zhao (2020-08-13 02:55:16) > > From: Qianli Zhao <zhaoqianli@...omi.com> > > > > Add debugobject support to track the life time of kthread_work > > Subject says 'objectdebug' but then this says debugobject. Use > debugobject throughout please. > > > which is used to detect reinitialization/free active object problems > > which is used to detect reinitialization/free active object problems. > > > Add kthread_init_work_onstack/kthread_init_delayed_work_onstack for > > kthread onstack support > > kthread onstack support. > > Also, mark functions with parenthesis please. > > > > > If we reinitialize a kthread_work that has been activated, > > this will cause delayed_work_list/work_list corruption. > > enable this config,there is an chance to fixup these errors > > Capitalize enable. > > > or WARNING the wrong use of kthread_work > > > > [30858.395766] list_del corruption. next->prev should be ffffffe388ebbf88, but was ffffffe388ebb588 > > [30858.395788] WARNING: CPU: 2 PID: 387 at /home/work/data/codes/build_home/kernel/msm-4.19/lib/list_debug.c:56 __list_del_entry_valid+0xc8/0xd0 > > ... > > [30858.405951] list_add corruption. next->prev should be prev (ffffffe389392620), but was ffffffe388ebbf88. (next=ffffffe388ebbf88). > > [30858.405977] WARNING: CPU: 0 PID: 7721 at /home/work/data/codes/build_home/kernel/msm-4.19/lib/list_debug.c:25 __list_add_valid+0x7c/0xc8 > > > > crash> struct kthread_worker.delayed_work_list 0xffffffe3893925f0 > > [ffffffe389392620] delayed_work_list = { > > next = 0xffffffe388ebbf88, > > prev = 0xffffffe388ebb588 > > } > > crash> list 0xffffffe388ebbf88 > > ffffffe388ebbf88 > > > > Signed-off-by: Qianli Zhao <zhaoqianli@...omi.com> > [...] > > diff --git a/include/linux/poison.h b/include/linux/poison.h > > index df34330..2e6a370 100644 > > --- a/include/linux/poison.h > > +++ b/include/linux/poison.h > > @@ -86,4 +86,7 @@ > > /********** security/ **********/ > > #define KEY_DESTROY 0xbd > > > > +/********** kernel/kthread **********/ > > +#define KWORK_ENTRY_STATIC ((void *) 0x600 + POISON_POINTER_DELTA) > > Can we get a comment above this like there is for TIMER_ENTRY_STATIC? > > > + > > #endif > > diff --git a/kernel/kthread.c b/kernel/kthread.c > > index 132f84a..68a16cc 100644 > > --- a/kernel/kthread.c > > +++ b/kernel/kthread.c > > @@ -67,6 +67,118 @@ enum KTHREAD_BITS { > > KTHREAD_SHOULD_PARK, > > }; > > > > +#ifdef CONFIG_DEBUG_OBJECTS_KTHREAD_WORK > > +static struct debug_obj_descr kwork_debug_descr; > > + > > +static void *kwork_debug_hint(void *addr) > > +{ > > + return ((struct kthread_work *) addr)->func; > > +} > > + > > +static bool kwork_is_static_object(void *addr) > > +{ > > + struct kthread_work *kwork = addr; > > + > > + return (kwork->node.prev == NULL && > > + kwork->node.next == KWORK_ENTRY_STATIC); > > +} > > + > > +static bool kwork_fixup_init(void *addr, enum debug_obj_state state) > > +{ > > + struct kthread_work *kwork = addr; > > + > > + switch (state) { > > + case ODEBUG_STATE_ACTIVE: > > + kthread_cancel_work_sync(kwork); > > + debug_object_init(kwork, &kwork_debug_descr); > > + return true; > > + default: > > + return false; > > + } > > +} > > + > > +static bool kwork_fixup_free(void *addr, enum debug_obj_state state) > > +{ > > + struct kthread_work *kwork = addr; > > + > > + switch (state) { > > + case ODEBUG_STATE_ACTIVE: > > + kthread_cancel_work_sync(kwork); > > + debug_object_free(kwork, &kwork_debug_descr); > > + return true; > > + default: > > + return false; > > + } > > +} > > + > > +static void stub_kthread_work(struct kthread_work *unuse) > > +{ > > + WARN_ON(1); > > +} > > + > > +static bool kwork_fixup_assert_init(void *addr, enum debug_obj_state state) > > +{ > > + struct kthread_work *kwork = addr; > > + switch (state) { > > + case ODEBUG_STATE_NOTAVAILABLE: > > + kthread_init_work(kwork, stub_kthread_work); > > + return true; > > + default: > > + return false; > > + } > > +} > > + > > +static struct debug_obj_descr kwork_debug_descr = { > > + .name = "kthread_work", > > + .debug_hint = kwork_debug_hint, > > + .is_static_object = kwork_is_static_object, > > + .fixup_init = kwork_fixup_init, > > + .fixup_free = kwork_fixup_free, > > + .fixup_assert_init = kwork_fixup_assert_init, > > Nitpick: This needs some formatting to deindent one tab and align the > equals signs. > > > +}; > > + > > +static inline void debug_kwork_activate(struct kthread_work *kwork) > > +{ > > + debug_object_activate(kwork, &kwork_debug_descr); > > +} > > + > > +static inline void debug_kwork_deactivate(struct kthread_work *kwork) > > +{ > > + debug_object_deactivate(kwork, &kwork_debug_descr); > > +} > > + > > +static inline void debug_kwork_assert_init(struct kthread_work *kwork) > > +{ > > + debug_object_assert_init(kwork, &kwork_debug_descr); > > +} > > + > > +void __init_kwork(struct kthread_work *kwork, int onstack) > > +{ > > + if (onstack) > > + debug_object_init_on_stack(kwork, &kwork_debug_descr); > > + else > > + debug_object_init(kwork, &kwork_debug_descr); > > +} > > +EXPORT_SYMBOL_GPL(__init_kwork); > > + > > +void destroy_kwork_on_stack(struct kthread_work *kwork) > > +{ > > + debug_object_free(kwork, &kwork_debug_descr); > > +} > > +EXPORT_SYMBOL_GPL(destroy_kwork_on_stack); > > + > > +void destroy_delayed_kwork_on_stack(struct kthread_delayed_work *kdwork) > > +{ > > + destroy_timer_on_stack(&kdwork->timer); > > + debug_object_free(&kdwork->work, &kwork_debug_descr); > > +} > > +EXPORT_SYMBOL_GPL(destroy_delayed_kwork_on_stack); > > +#else > > +static inline void debug_kwork_activate(struct kthread_work *kwork) { } > > +static inline void debug_kwork_deactivate(struct kthread_work *kwork) { } > > +static inline void debug_kwork_assert_init(struct kthread_work *kwork) { } > > +#endif > > + > > static inline void set_kthread_struct(void *kthread) > > { > > /* > > @@ -697,6 +809,7 @@ int kthread_worker_fn(void *worker_ptr) > > if (!list_empty(&worker->work_list)) { > > work = list_first_entry(&worker->work_list, > > struct kthread_work, node); > > + debug_kwork_deactivate(work); > > list_del_init(&work->node); > > } > > worker->current_work = work; > > @@ -833,8 +946,10 @@ static void kthread_insert_work(struct kthread_worker *worker, > > { > > kthread_insert_work_sanity_check(worker, work); > > > > + debug_kwork_activate(work); > > list_add_tail(&work->node, pos); > > work->worker = worker; > > + > > Drop this newline. > > > if (!worker->current_work && likely(worker->task)) > > wake_up_process(worker->task); > > } > > @@ -857,6 +972,7 @@ bool kthread_queue_work(struct kthread_worker *worker, > > bool ret = false; > > unsigned long flags; > > > > + debug_kwork_assert_init(work); > > raw_spin_lock_irqsave(&worker->lock, flags); > > if (!queuing_blocked(worker, work)) { > > kthread_insert_work(worker, work, &worker->work_list); > > @@ -895,6 +1011,7 @@ void kthread_delayed_work_timer_fn(struct timer_list *t) > > > > /* Move the work from worker->delayed_work_list. */ > > WARN_ON_ONCE(list_empty(&work->node)); > > + debug_kwork_deactivate(work); > > list_del_init(&work->node); > > kthread_insert_work(worker, work, &worker->work_list); > > > > @@ -924,7 +1041,7 @@ static void __kthread_queue_delayed_work(struct kthread_worker *worker, > > > > /* Be paranoid and try to detect possible races already now. */ > > kthread_insert_work_sanity_check(worker, work); > > - > > + debug_kwork_activate(work); > > list_add(&work->node, &worker->delayed_work_list); > > work->worker = worker; > > timer->expires = jiffies + delay; > > @@ -954,6 +1071,7 @@ bool kthread_queue_delayed_work(struct kthread_worker *worker, > > unsigned long flags; > > bool ret = false; > > > > + debug_kwork_assert_init(work); > > raw_spin_lock_irqsave(&worker->lock, flags); > > > > if (!queuing_blocked(worker, work)) { > > @@ -987,15 +1105,16 @@ static void kthread_flush_work_fn(struct kthread_work *work) > > void kthread_flush_work(struct kthread_work *work) > > { > > struct kthread_flush_work fwork = { > > - KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), > > - COMPLETION_INITIALIZER_ONSTACK(fwork.done), > > + .done = COMPLETION_INITIALIZER_ONSTACK(fwork.done), > > }; > > struct kthread_worker *worker; > > bool noop = false; > > > > + kthread_init_work_onstack(&fwork.work, kthread_flush_work_fn); > > + debug_kwork_assert_init(work); > > worker = work->worker; > > if (!worker) > > - return; > > + goto out; > > Why make the worker and init it on the stack if there isn't anything to > do? The !worker check should be early and then bail out before doing > anything else. > > > > > raw_spin_lock_irq(&worker->lock); > > /* Work must not be used with >1 worker, see kthread_queue_work(). */ > > @@ -1013,6 +1132,9 @@ void kthread_flush_work(struct kthread_work *work) > > > > if (!noop) > > wait_for_completion(&fwork.done); > > + > > +out: > > Then this label can be dropped. > > > + destroy_kwork_on_stack(&fwork.work); > > } > > EXPORT_SYMBOL_GPL(kthread_flush_work); > >
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