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From: "Rémi Denis-Courmont" <rem@videolan.org>
To: alsa-devel@alsa-project.org
Subject: How to close ALSA device nodes?
Date: Sun, 18 Oct 2009 19:06:25 +0300	[thread overview]
Message-ID: <200910181906.25790.rem@videolan.org> (raw)

	Hello,

I'm getting a bug report against VLC media player whereby ALSA sound output 
stops working when the screensaver is inhibited. It turns out that VLC is 
leaking any file descriptor open through ALSA-lib into child processes. The 
exact same issue was already raised by mplayer... 6 years ago:
http://www.mail-archive.com/alsa-devel@lists.sourceforge.net/msg06249.html

In other cases (V4L, OSS, DVB, DVD, sockets, even regular files...), VLC would 
open the device nodes with O_CLOEXEC flag (if supported by kernel and libc) 
and fallback to setting FD_CLOEXEC via fcntl(). Then the descriptor is 
automatically, and in the earlier case, thread-safely, closed whenever VLC -
forks and- execs. With ALSA-lib, I cannot figure any way to achieve that...

From the earlier thread, I reckon that ALSA developers consider that this is 
an upper-layer issue. Maybe so, but then how is the upper-layer supposed to 
find which file descriptors ALSA-lib has opened - if any? Conversely, if ALSA-
lib won't tell while file descriptors it is using, what could possibly be the 
use case for not closing those on exec?

Best regards,

-- 
Rémi Denis-Courmont
http://www.remlab.net/
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             reply	other threads:[~2009-10-18 16:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-18 16:06 Rémi Denis-Courmont [this message]
2009-10-18 17:13 ` How to close ALSA device nodes? Robert Hancock
  -- strict thread matches above, loose matches on Subject: below --
2009-10-18 17:38 Rémi Denis-Courmont
2009-10-22 22:55 ` Daniel Yek
2009-10-23  9:49   ` Rémi Denis-Courmont
2009-10-18 16:02 Rémi Denis-Courmont

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