From: Alan Cox <alan@linux.intel.com>
To: balbi@ti.com
Cc: Marcel Holtmann <marcel@holtmann.org>,
Greg KH <gregkh@linuxfoundation.org>,
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: Re: hci_ldsic nested locking problem
Date: Thu, 20 Mar 2014 16:42:16 +0000 [thread overview]
Message-ID: <1395333736.22077.32.camel@acox1-desk.ger.corp.intel.com> (raw)
In-Reply-To: <20140320163435.GH32692@saruman.home>
On Thu, 2014-03-20 at 11:34 -0500, Felipe Balbi wrote:
> 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() ?
It isn't because you might send all the bytes and go
write
write_wakeup
write
write wakeup
...
and recurse
Alan
next prev parent reply other threads:[~2014-03-20 16:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-20 16:34 Felipe Balbi
2014-03-20 16:42 ` Alan Cox [this message]
2014-03-20 17:16 ` Felipe Balbi
2014-03-20 17:29 ` Felipe Balbi
2014-03-20 17:34 ` Peter Hurley
2014-03-20 17:35 ` Felipe Balbi
2014-03-20 18:45 ` Greg KH
2014-03-20 18:54 ` Peter Hurley
2014-03-20 17:31 ` Peter Hurley
2014-03-20 18:11 ` Felipe Balbi
2014-03-20 18:21 ` Peter Hurley
2014-03-20 18:25 ` Felipe Balbi
2014-03-20 19:01 ` Felipe Balbi
2014-03-20 19:03 ` Felipe Balbi
2014-03-20 19:16 ` Peter Hurley
2014-03-20 19:25 ` Felipe Balbi
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