[Pkg-xfce-devel] Bug#642397: Bug#642397: Bug#642397: xfce4-power-manager: Segfault when docking

Yves-Alexis Perez corsac at debian.org
Thu Mar 29 08:39:19 UTC 2012

On sam., 2011-10-22 at 22:57 +0200, Jö Fahlke wrote:
> tags 642397 +patch
> thanks
> Hi!
> The problem, as far as I figured it out, is apparently twofold:
>  1. At some point xfpm_battery_notify() is called with some XfpmBattery
>     object.  If notifications are enabled, it will add a source with idle
>     priority which holds a pointer to this object and has
>     xfpm_battery_notify_idle() as its callback function.
>  2. After xfpm_battery_notify() returns, the XfpmBattery object is entered
>     into some hash table.
>  3. Later the source invokes xfpm_battery_notify_idle().  The XfpmBattery
>     object that is passed as an argument is usually valid.  But sometimes it
>     has a reference count of 0 and priv == NULL.
> What happens is that sometimes XfpmBattery object is removed from the hash and
> freed between 2. and 3.  Apparently my hal sends an add and an remove message
> for the same battery immediately after each other.
> The attached patch fixes this by calling g_object_ref() on the
> XfpmBatteryObject in xfpm_battery_notify() before g_idle_add() is called to
> add the source.  The corresponding unref happens unconditionally in
> xfpm_battery_notify_idle() -- that function returns FALSE, which means the
> source holding the pointer to the XfpmBattery object is removed after it's
> callback returns.
> Please, somebody review this patch, I'm really quite new to glib and gobject
> -- I may have easily overlooked something, or violated some convention.
> (Like: is the source's callback always called, or are there cases where the
> source gets removed without beeing called?  That would create a memory leak.)
> Anyway, I'm going to run the patched xfpm for a while and will report back if
> notice any further problems.
> Bye,
> Jö.
By the way, does this still happen? 1.0.10-5 (uploaded on feb 2012) has
a patch which might fix your issue.

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