From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-rt-users@vger.kernel.org
Subject: Re: [3.4-rt] backport of completion-use-simple-wait-queues.patch
Date: Fri, 29 Nov 2013 13:49:31 +0100 [thread overview]
Message-ID: <20131129124931.GA31099@linutronix.de> (raw)
In-Reply-To: <20131128201029.GA28966@windriver.com>
* Paul Gortmaker | 2013-11-28 15:10:29 [-0500]:
>Hi Steve,
Hi Paul,
>Someone tripped over this with usb console:
>
> in_atomic(): 0, irqs_disabled(): 1, pid: 36, name: kworker/1:1
> Pid: 36, comm: kworker/1:1 Tainted: G O 3.4.34-rt40_preempt-rt #1
> Call Trace:
> [<c105461e>] __might_sleep+0xce/0xf0
> [<c14fe24c>] rt_spin_lock+0x1c/0x40
> [<c1056f65>] complete+0x25/0x60
> [<c14fde10>] ? rt_mutex_lock+0x20/0x50
> [<c135e1b0>] usb_stor_blocking_completion+0x10/0x20
> [<c13317b7>] usb_poll_irq_flush_helper+0x67/0xf0
> [<c1056ad4>] ? migrate_enable+0x74/0x170
> [<c10427f7>] process_one_work+0x107/0x410
git grep usb_poll_irq_flush_helper
shows no results in 3.4.61-rt77 and 3.6.11.9-rt42.
The function seems to disable interrups and it completes a usb-storage
request. This would works on mainline but in -RT those things run in thread
context (usb-hcd-use-local-irq-nort.patch).
Depending on what urbs you complete via usb_poll_irq_flush_helper() you
could deadlock if the urb-complete handler grabs a lock.
>Thanks,
>Paul.
Sebastian
next prev parent reply other threads:[~2013-11-29 12:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-28 20:10 [3.4-rt] backport of completion-use-simple-wait-queues.patch Paul Gortmaker
2013-11-29 12:49 ` Sebastian Andrzej Siewior [this message]
2013-11-29 15:11 ` Paul Gortmaker
2013-11-29 22:21 ` Steven Rostedt
2013-11-29 23:29 ` Paul Gortmaker
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