From: Sebastian Harl <sh@tokkee.org>
Date: Thu, 18 Sep 2008 09:05:48 +0000 (+0200)
Subject: Added debian/patches/perl_deadlock.dpatch.
X-Git-Tag: collectd-4.4.2-2~2
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=6379e4648e58db3eca532e133a53942dffbcd035;p=pkg-collectd.git

Added debian/patches/perl_deadlock.dpatch.

Upstream patch to fix a possible deadlock in the perl plugin.

Closes: #499179
---

diff --git a/debian/changelog b/debian/changelog
index 97ca2b4..a4aecb2 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -4,6 +4,8 @@ collectd (4.4.2-2) unstable; urgency=low
     in 4.4.1-1 and instead build depend on libopenipmi-dev (>= 2.0.14-1~)
     which includes fixed .pc files. This fixes an undefined symbol error when
     loading the ipmi plugin caused by that work around (Closes: #494665).
+  * Added debian/patches/perl_deadlock.dpatch - upstream patch to fix a
+    possible deadlock in the perl plugin (Closes: #499179).
   * Added debian/patches/memory_libstatgrab.dpatch - trivial upstream patch to
     fix a typo in the libstatgrab code of the memory plugin.
   * Added debian/patches/collectd_memleak.dpatch - trivial upstream patch to
@@ -15,7 +17,7 @@ collectd (4.4.2-2) unstable; urgency=low
   * Added debian/patches/memcached_timeout.dpatch - trivial upstream patch to
     fix the timeout passed to poll(2).
 
- -- Sebastian Harl <sh@tokkee.org>  Wed, 17 Sep 2008 20:08:55 +0200
+ -- Sebastian Harl <sh@tokkee.org>  Thu, 18 Sep 2008 11:03:50 +0200
 
 collectd (4.4.2-1) unstable; urgency=low
 
diff --git a/debian/patches/00list b/debian/patches/00list
index c72403e..066e8e9 100644
--- a/debian/patches/00list
+++ b/debian/patches/00list
@@ -6,4 +6,5 @@ collectd_memleak.dpatch
 snmp_memleak.dpatch
 memcached_fdleak.dpatch
 memcached_timeout.dpatch
+perl_deadlock.dpatch
 
diff --git a/debian/patches/perl_deadlock.dpatch b/debian/patches/perl_deadlock.dpatch
new file mode 100755
index 0000000..bc9d3d1
--- /dev/null
+++ b/debian/patches/perl_deadlock.dpatch
@@ -0,0 +1,78 @@
+#! /bin/sh /usr/share/dpatch/dpatch-run
+## perl_deadlock.dpatch by Sebastian Harl <sh@tokkee.org>
+##
+## DP: Collectd.pm: Improved the way access to @plugins is synchronized.
+## DP:
+## DP: So far, a lock has been placed on @plugins, so that no two threads could
+## DP: access the list of plugins simultaneously. This could cause problems
+## DP: which in certain situations could even lead to deadlocks. E.g. when
+## DP: using the perl plugin in combination with the rrdtool plugin with
+## DP: debugging enabled one would get hit by the following situation: the perl
+## DP: plugin holds the lock on @plugins and then dispatches values to the
+## DP: rrdtool plugin from some Perl plugin's read function. The rrdtool plugin
+## DP: then tries to acquire its cache lock. At the same time some other plugin
+## DP: dispatches values to the rrdtool plugin as well and this thread now
+## DP: holds the lock on the rrdtool cache. While holding that lock, the
+## DP: rrdtool plugin might dispatch a debug logging message and thus calls the
+## DP: perl plugin's log-callback which tries to get the lock on @plugins thus
+## DP: causing a deadlock.
+## DP:
+## DP: This has been resolved by the following two changes:
+## DP:
+## DP:  * Restrict the lock to the list of plugins of one type. This allows to
+## DP:    access e.g. read and log plugins in parallel.
+## DP:
+## DP:  * Unlock the variable before calling the Perl callback function. This
+## DP:    further prevents nested locks.
+## DP:
+## DP: (This is upstream Git commit dffb71cd6668e98f93c12da2ee2bd7a728d7292a)
+
+@DPATCH@
+
+diff a/bindings/perl/Collectd.pm b/bindings/perl/Collectd.pm
+--- a/bindings/perl/Collectd.pm
++++ b/bindings/perl/Collectd.pm
+@@ -133,6 +133,8 @@ sub DEBUG   { _log (scalar caller, LOG_DEBUG,   shift); }
+ sub plugin_call_all {
+ 	my $type = shift;
+ 
++	my %plugins;
++
+ 	our $cb_name = undef;
+ 
+ 	if (! defined $type) {
+@@ -148,9 +150,13 @@ sub plugin_call_all {
+ 		return;
+ 	}
+ 
+-	lock @plugins;
+-	foreach my $plugin (keys %{$plugins[$type]}) {
+-		my $p = $plugins[$type]->{$plugin};
++	{
++		lock %{$plugins[$type]};
++		%plugins = %{$plugins[$type]};
++	}
++
++	foreach my $plugin (keys %plugins) {
++		my $p = $plugins{$plugin};
+ 
+ 		my $status = 0;
+ 
+@@ -261,7 +267,7 @@ sub plugin_register {
+ 			cb_name   => $data,
+ 		);
+ 
+-		lock @plugins;
++		lock %{$plugins[$type]};
+ 		$plugins[$type]->{$name} = \%p;
+ 	}
+ 	else {
+@@ -286,7 +292,7 @@ sub plugin_unregister {
+ 		return plugin_unregister_data_set ($name);
+ 	}
+ 	elsif (defined $plugins[$type]) {
+-		lock @plugins;
++		lock %{$plugins[$type]};
+ 		delete $plugins[$type]->{$name};
+ 	}
+ 	else {