lkml.org 
[lkml]   [2009]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRE: [PATCH] tty: Fix tcdrain hang due to tty chars_in_buffer errors
Date
From
That was my other thought, but there are other kernel drivers which do
report errors from chars_in_buffer. A grep of the code shows
ipw_chars_in_buffer in drivers/char/pcmcia/ipwireless/tty.c,
hvc_chars_in_buffer in hvc_console.c, ntty_chars_in_buffer in nozomi.c,
if_chars_in_buffer in isdn/gigaset/interface.c, etc. Do they all need
to be updated?

Should the return type be unsigned int to make the behavior more
explicit? The signed type may be interpreted along the lines of a read
or write call which returns a count or a negative value to indicate a
failure.

Jeff

-----Original Message-----
From: Alan Cox [mailto:alan@lxorguk.ukuu.org.uk]
Sent: Friday, July 17, 2009 12:01 PM
To: Harris, Jeff
Cc: alan@linux.intel.com; vapier@gentoo.org; adobriyan@gmail.com;
linux-kernel@vger.kernel.org; Harris, Jeff
Subject: Re: [PATCH] tty: Fix tcdrain hang due to tty chars_in_buffer
errors

On Fri, 17 Jul 2009 11:07:54 -0400
Jeff Harris <jeff_harris@kentrox.com> wrote:

> If a tty driver's chars_in_buffer callback reports an error, the wait
loop in

chars_in_buffer cannot report an error. It reports how many characters
are in the buffer.

> A process calling tcdrain will block indefinitely if it calls tcdrain
when the
> device is disconnected.

Fix your chars_in_buffer. On a disconnect its quite reasonable to return
0, as they are not buffered any more.

Alan



\
 
 \ /
  Last update: 2009-07-17 18:39    [W:0.031 / U:54.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site