From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753314AbcCBIeu (ORCPT ); Wed, 2 Mar 2016 03:34:50 -0500 Received: from mail-vk0-f49.google.com ([209.85.213.49]:33923 "EHLO mail-vk0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167AbcCBIes (ORCPT ); Wed, 2 Mar 2016 03:34:48 -0500 MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: References:

Date: Wed, 2 Mar 2016 09:34:46 +0100 Message-ID: Subject: Re: [PATCH] usbhid: Fix lockdep unannotated irqs-off warning From: Sedat Dilek To: Alan Stern Cc: Steven Rostedt , Jiri Kosina , Tejun Heo , Lai Jiangshan , Benjamin Tissoires , Paul McKenney , Andy Lutomirski , LKML , linux-usb@vger.kernel.org, Greg Kroah-Hartman , Peter Zijlstra , Ingo Molnar Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/2/16, Sedat Dilek wrote: > On 3/1/16, Alan Stern wrote: >> On Tue, 1 Mar 2016, Sedat Dilek wrote: >> >>> On Tue, Oct 13, 2015 at 2:57 AM, Steven Rostedt >>> wrote: >>> > On Sat, 3 Oct 2015 12:05:42 +0200 >>> > Sedat Dilek wrote: >>> > >>> >> So, at the beginning... dunno WTF is causing the problems - no >>> >> workaround for CLANG. >>> > >>> > Probably need to compile with gcc and with clang and look at the >>> > binary >>> > differences. Or at least what objdump shows. >>> > >>> >>> [ Hope to address this issue to the correct people - CCed some people >>> I taped on their nerves ] >>> >>> Not sure if I should open a new thread? >>> Please, some clear statements on this. >>> Thanks. >>> >>> The issue is still visible and alive. >> >> ... >> >>> [ FACT #3: TEST-CASE #2 ] >>> >>> The most reliable test-case is to simply unplug my external Logitech >>> USB mouse - saw this by accident. >>> YES, it was so simple. >>> >>> --- dmesg_4.5.0-rc6-2-llvmlinux-amd64.txt 2016-02-29 >>> 21:23:56.399691975 +0100 >>> +++ dmesg_4.5.0-rc6-2-llvmlinux-amd64_usbmouse-unplugged.txt >>> 2016-02-29 21:28:14.401832240 +0100 >>> @@ -832,3 +832,75 @@ >>> [ 66.529779] PPP BSD Compression module registered >>> [ 66.563013] PPP Deflate Compression module registered >>> [ 66.978977] usb 2-1.5: USB disconnect, device number 4 >>> +[ 321.937369] usb 2-1.4: USB disconnect, device number 3 >>> +[ 321.950810] BUG: sleeping function called from invalid context at >>> kernel/workqueue.c:2785 >>> +[ 321.950816] in_atomic(): 0, irqs_disabled(): 1, pid: 44, name: >>> kworker/2:1 >> >>> +[ 321.950885] hardirqs last enabled at (47769): >>> [] _raw_spin_unlock_irq+0x32/0x60 >>> +[ 321.950889] hardirqs last disabled at (47770): >>> [] del_timer_sync+0x3c/0x110 >>> +[ 321.950894] softirqs last enabled at (47112): >>> [] __do_softirq+0x5a2/0x610 >>> +[ 321.950898] softirqs last disabled at (47097): >>> [] irq_exit+0x9c/0x120 >>> +[ 321.950903] CPU: 2 PID: 44 Comm: kworker/2:1 Not tainted >>> 4.5.0-rc6-2-llvmlinux-amd64 #1 >>> +[ 321.950905] Hardware name: SAMSUNG ELECTRONICS CO., LTD. >>> 530U3BI/530U4BI/530U4BH/530U3BI/530U4BI/530U4BH, BIOS 13XK 03/28/2013 >>> +[ 321.950908] Workqueue: usb_hub_wq hub_event >>> +[ 321.950911] ffff8800d3326948 0000000000000092 0000000000000000 >>> ffff8800d4347568 >>> +[ 321.950915] ffffffff814ba7d4 ffff8800d43474f8 ffff8800d4340cc0 >>> ffff8800d4347568 >>> +[ 321.950919] ffffffff810e28fd 0000000000000092 0000000000000096 >>> ffff8800d43475a8 >>> +[ 321.950923] Call Trace: >>> +[ 321.950927] [] dump_stack+0xa4/0xf0 >>> +[ 321.950931] [] ? print_irqtrace_events+0xcd/0xe0 >>> +[ 321.950936] [] ___might_sleep+0x295/0x2b0 >>> +[ 321.950939] [] __might_sleep+0x4f/0xc0 >>> +[ 321.950943] [] start_flush_work+0x2f/0x2a0 >>> +[ 321.950946] [] flush_work+0x5c/0x80 >>> +[ 321.950949] [] ? flush_work+0x1a/0x80 >>> +[ 321.950953] [] ? trace_hardirqs_off+0xd/0x10 >>> +[ 321.950956] [] ? try_to_grab_pending+0x4a/0x260 >>> +[ 321.950960] [] __cancel_work_timer+0x197/0x290 >>> +[ 321.950963] [] ? try_to_del_timer_sync+0xad/0xc0 >>> +[ 321.950966] [] cancel_work_sync+0x18/0x20 >> >> It's possible that this could be a compiler-related error connected >> with local_irq_save(). __cancel_work_timer() calls >> >> ret = try_to_grab_pending(work, is_dwork, &flags); >> >> and try_to_grab_pending() starts this way: >> >> static int try_to_grab_pending(struct work_struct *work, bool is_dwork, >> unsigned long *flags) >> { >> struct worker_pool *pool; >> struct pool_workqueue *pwq; >> >> local_irq_save(*flags); >> >> Then later on, __cancel_work_timer() does >> >> local_irq_restore(flags); >> >> Maybe CLANG doesn't like local_irq_save() applied to a pointer as >> opposed to a stack variable. >> >> As a quick test, try applying the patch below. (Note that there is a >> similar construction in kernel/signal.c.) >> >> Alan Stern >> >> >> >> Index: usb-4.4/kernel/workqueue.c >> =================================================================== >> --- usb-4.4.orig/kernel/workqueue.c >> +++ usb-4.4/kernel/workqueue.c >> @@ -1175,12 +1175,14 @@ out_put: >> * This function is safe to call from any context including IRQ handler. >> */ >> static int try_to_grab_pending(struct work_struct *work, bool is_dwork, >> - unsigned long *flags) >> + unsigned long *pflags) >> { >> struct worker_pool *pool; >> struct pool_workqueue *pwq; >> + unsigned long flags; >> >> - local_irq_save(*flags); >> + local_irq_save(flags); >> + *pflags = flags; >> >> /* try to steal the timer if it exists */ >> if (is_dwork) { >> @@ -1241,7 +1243,7 @@ static int try_to_grab_pending(struct wo >> } >> spin_unlock(&pool->lock); >> fail: >> - local_irq_restore(*flags); >> + local_irq_restore(flags); >> if (work_is_canceling(work)) >> return -ENOENT; >> cpu_relax(); >> >> > > might_sleep() is invoked in start_flush_work(), but there are no > "flags" passed to local_irq_{disable,enable}. > > What about something like this? > > @@ -2781,13 +2783,14 @@ static bool start_flush_work(struct > work_struct *work, struct wq_barrier *barr) > struct worker *worker = NULL; > struct worker_pool *pool; > struct pool_workqueue *pwq; > + unsigned long flags; > > might_sleep(); > > - local_irq_disable(); > + local_irq_disable(flags); > pool = get_work_pool(work); > if (!pool) { > - local_irq_enable(); > + local_irq_enable(flags); > return false; > } > start_flush_work() is the only place where no flags are passed. That stuff above does not work - no clue how to do that. Any help? Then I see there... ... spin_lock(&pool->lock); ... spin_unlock_irq(&pool->lock); ... Should that be spin_lock_irq()? static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) { struct worker *worker = NULL; struct worker_pool *pool; struct pool_workqueue *pwq; might_sleep(); local_irq_disable(); pool = get_work_pool(work); if (!pool) { local_irq_enable(); return false; } spin_lock(&pool->lock); <--- XXX: spin_lock_irq() ??? /* see the comment in try_to_grab_pending() with the same code */ pwq = get_work_pwq(work); if (pwq) { if (unlikely(pwq->pool != pool)) goto already_gone; } else { worker = find_worker_executing_work(pool, work); if (!worker) goto already_gone; pwq = worker->current_pwq; } check_flush_dependency(pwq->wq, work); insert_wq_barrier(pwq, barr, work, worker); spin_unlock_irq(&pool->lock); /* * If @max_active is 1 or rescuer is in use, flushing another work * item on the same workqueue may lead to deadlock. Make sure the * flusher is not running on the same workqueue by verifying write * access. */ if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) lock_map_acquire(&pwq->wq->lockdep_map); else lock_map_acquire_read(&pwq->wq->lockdep_map); lock_map_release(&pwq->wq->lockdep_map); return true; already_gone: spin_unlock_irq(&pool->lock); return false; } - Sedat -