Pulseaudio device removal

From 16cf0606fd59484236356e400a89c083e76da64b Mon Sep 17 00:00:00 2001

During a long time, the removal of an alsa drivers were a problem for me, and other developers reported to have the same problem.

With Hans de Goede help, I've got the pulseaudio syntax that allows releasing an alsa device. With that, I've added a patch to the media build that will automatically handle it, when "make rmmod" is called.

Feel free to test and give some feedback. I suspect that the logic will need more hacks, as pulseaudio-libs is not capable of detecting the name of some USB alsa drivers.

The logic there is not optimized: It is basically running pacmd list-sources and pacmd list-sinks several times, as I didn't have time yet to optimize. I'll probably do it soon, after finishing some other things.

Enjoy!
Mauro.

Quoted 1 line

From 16cf0606fd59484236356e400a89c083e76da64b Mon Sep 17 00:00:00 2001

From: Mauro Carvalho Chehab<[email protected]>
Date: Fri, 17 Jun 2011 16:48:04 -0300
Subject: [PATCH] rmmod.pl: Add a logic to allow removing audio modules with pulseaudio

Pulseaudio keeps audio devices opened forever. In order to be able to remove a device, pulseaudio needs to de-allocate the device.

Unfortunately, pulseaudio recognizes alsa drivers as "module" (an integer number, not related to the device nodename), and only allows module removal if running with user matches the console owner.

The logic inside rmmod.pl will now take the above into account. So, it will detect if pulseaudio is running. If it is, it will:

1) list the pulseaudio modules with "pacmd list-sinks" and "pacmd list-sources"

2) detect if any of the modules there is provided by a v4l device;

3) If they're provided by a video device, it removes the module with:
pactl unload-module 26

Even the above logic is not perfect as, due to a pulseaudio libs bug, pulseaudio can't detect the name of em28xx-alsa driver, as it uses the same interface as the video node. Similar hacks will may be needed for other USB devices, like tm6000 and cx231xx.

Signed-off-by Mauro Carvalho Chehab<[email protected]>

build.sh +2 -0

index 60d0c26..3cc21f8 100755
@@ -12,6 +12,8 @@ echo "Checking if the needed tools are present"
  run ./check_needs.pl
  echo "Checking for Digest::SHA1 (package perl-Digest-SHA1)"
  run perl -MDigest::SHA1 -e 1
+echo "Checking for Proc::ProcessTable (package perl-Proc-ProcessTable)"
+run perl -MProc::ProcessTable -e 1
  echo
  echo "************************************************************"
  echo "* This script will download the latest tarball and build it*"

v4l/scripts/rmmod.pl +69 -3

index ed79cbe..53ea451 100755
@@ -1,6 +1,8 @@
  #!/usr/bin/perl
  use strict;
  use File::Find;
+use Proc::ProcessTable;
+
 
  my %depend = ();
  my %depend2 = ();

@@ -166,6 +168,69 @@ sub insmod ($)
  	}
  }
 
+my @pulse;
+my $try_pulseaudio = 1;
+
+sub check_pulseaudio()
+{
+	my $t = new Proc::ProcessTable;
+	foreach my $p ( @{$t->table} ) {
+		push @pulse, $p->uid if ($p->cmndline =~m,/pulseaudio ,);
+	}
+	$try_pulseaudio = 0 if (!@pulse);
+
+	print "Pulseaudio is running with UUID(s): @pulse\n";
+}
+
+sub unload_pulseaudio($)
+{
+	my $driver_name = shift;
+	my $cur_module;
+
+	return if (!$try_pulseaudio);
+
+	check_pulseaudio() if (!@pulse);
+	return if (!$try_pulseaudio);
+
+	for my $pid (@pulse) {
+#		printf "LANG=C sudo -u \\\#$pid pacmd list-sources |\n";
+		open IN, "LANG=C sudo -u \\\#$pid pacmd list-sources |";
+		while (<IN>) {
+			$cur_module = $1 if (/^\s*module:\s*(\d+)/);
+
+			if (/^\s*alsa.driver_name\s*=\s*"(.*)"/) {
+				if ($1 eq $driver_name) {
+					print "LANG=C sudo -u \\#$pid pactl unload-module $cur_module\n";
+					system ("LANG=C sudo -u \\#$pid pactl unload-module $cur_module");
+				}
+				next;
+			}
+
+			# Special case: em28xx sometimes use a Vendor Class at
+			# the same interface as the video node. Pulseaudio can't
+			# get the driver name in this case
+			if (/^\s*alsa.card_name\s*=\s*"Em28xx/) {
+				print "LANG=C sudo -u \\#$pid pactl unload-module $cur_module\n";
+				system ("LANG=C sudo -u \\#$pid pactl unload-module $cur_module");
+			}
+		}
+		close IN;
+
+#		printf "LANG=C sudo -u \\\#$pid pacmd list-sinks |\n";
+		open IN, "LANG=C sudo -u \\#$pid pacmd list-sinks |" or return;
+		while (<IN>) {
+			$cur_module = $1 if (/^\s*module:\s*(\d+)/);
+			if (/^\s*alsa.driver_name\s*=\s*"(.*)"/) {
+				if ($1 eq $driver_name) {
+					print "LANG=C sudo -u \\#$pid pactl unload-module $1\n";
+					system ("LANG=C sudo -u \\#$pid pactl unload-module $1");
+				}
+			}
+		}
+	}
+	close IN;
+}
+
  sub rmmod(@)
  {
  	my $rmmod = findprog('rmmod');

@@ -173,8 +238,10 @@ sub rmmod(@)
  	foreach (reverse @_) {
  		s/-/_/g;
  		if (exists ($loaded{$_})) {
-			print "$rmmod $_\n";
-			unshift @not, $_ if (system "$rmmod $_");
+			my $module = $_;
+			print "$rmmod $module\n";
+			unload_pulseaudio($module);
+			unshift @not, $module if (system "$rmmod $module");
  		}
  	}
  	return @not;
--

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Mauro:

The change in build.sh
http://git.linuxtv.org/media_build.git?a=commitdiff;h=16cf0606fd59484236356e400a89c083e76da64b

now requires installation of a Perl package Proc::ProcessTable that is not present in standard Ubuntu systems.

I needed to run
sudo aptitude install libproc-processtable-perl
before I could continue after the change.

Is there a way around this ?

From what I understand, the standard Ubuntu repositories already provide a package

Em 18-06-2011 14:20, Jan Hoogenraad escreveu:

Quoted 5 lines

Mauro:

The change in build.sh
http://git.linuxtv.org/media_build.git?a=commitdiff;h=16cf0606fd59484236356e400a89c083e76da64b

Quoted 7 lines

now requires installation of a Perl package Proc::ProcessTable that is not present in standard Ubuntu systems.

I needed to run
sudo aptitude install libproc-processtable-perl
before I could continue after the change.

Is there a way around this ?

The media_build requires several packages that may not be present on some installation. The build.sh script has a logic to detect the missing parts and to output what's the missing requirements:

echo "Checking if the needed tools are present"
run ./check_needs.pl

(I moved right now the perl-specific checks into check_needs.pl script)

Unfortunately, package names are distro-specific. So, as I use only Fedora/RHEL here, the only hints it have are for them. From my experiences, between the rpm-based distros, the package names are either equal or very close, so such hints probably are probably good enough for Suse and Mandriva users.

Quoted 1 line

From what I understand, the standard Ubuntu repositories already provide a package

for Proc::ProcessTable. So, the only thing that it is not ok is the package name hint.

Could you please provide us a patch adding the Ubuntu (and likely Debian) package name?

IMHO, the better would be to modify the check logic, in order to check what's the system, and provide a hint based on it. If the OS type is not found, then fall back to some default.

I think that the LSB default to get the distribution is by reading /etc/system-release. Those are provided on RHEL6 and Fedora (plus, the old way: /etc/redhat-release).

So, IMHO, all we need to do is to write a logic for the error report part of the check, that opens /etc/system-release, identify what's the distro, and provide the package name and some instructions on how to install the missing parts to the userspace.

The right way for adding such logic would be to install the OS's on some VM with the minimum install, run the script and add the missing parts on it.

Cheers,
Mauro.

Mauro:

You are completely right. Getting the packages automatically is very user-friendly. Furthermore, this will make media_build a great place to start of users stuck with older kernels.

On Ubuntu, the package name is libproc-processtable-perl
the command to install it is (on Ubuntu, usually no root user is used, but rather per command invokation).

The command for installation will be:

sudo apt-get install libproc-processtable-perl

There is no
/etc/system-release
on my system

However, there is a file /etc/lsb-release
cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=10.04
DISTRIB_CODENAME=lucid
DISTRIB_DESCRIPTION="Ubuntu 10.04.2 LTS"

I will make an updated script in the next week.