From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751693AbcCBGgi (ORCPT ); Wed, 2 Mar 2016 01:36:38 -0500 Received: from mail-vk0-f46.google.com ([209.85.213.46]:36283 "EHLO mail-vk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750978AbcCBGgg (ORCPT ); Wed, 2 Mar 2016 01:36:36 -0500 MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: References:

Date: Wed, 2 Mar 2016 07:36:35 +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 , Felipe Balbi , 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 3/1/16, 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; } - Sedat -