Return-Path: <cyrus@holtmann.org>
Date: Thu, 20 Mar 2014 11:34:35 -0500
From: Felipe Balbi <balbi@ti.com>
To: Marcel Holtmann <marcel@holtmann.org>, Alan Cox <alan@linux.intel.com>,
        Greg KH <gregkh@linuxfoundation.org>
CC: Muralidharan Karicheri <m-karicheri2@ti.com>,
        <linux-bluetooth@vger.kernel.org>, <linux-serial@vger.kernel.org>,
        Linux
 Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: hci_ldsic nested locking problem
Message-ID: <20140320163435.GH32692@saruman.home>
Reply-To: <balbi@ti.com>
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Hi,

when 8250 driver calls uart_write_wakeup(), the tty port lock is already
taken. hci_ldisc.c's implementation of ->write_wakeup() calls
tty->ops->write() to actually send the characters, but that call will
try to acquire the same port lock again.

Looking at other line disciplines that looks like a bug in hci_ldisc.c.
Am I correct to assume that ->write_wakeup() is supposed to *just*
wakeup the bottom half so we handle ->write() in another context ?

Is it legal to call tty->ops->write() from within ->write_wakeup() ?

cheers

--=20
balbi

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