On Thu, Feb 20, 2014 at 02:22:53PM +0100, Compostella, Jeremy wrote: > From: "Compostella, Jeremy" <jeremy.compostella@xxxxxxxxx> > > This bug can manifest itself in several situations, here is the one that made me > hunt it last week: > > When an Android device is encrypted, Android starts all the init services of > core and main levels, then it asks for the password and checks it trying to > mount /data. On success, it kills all the main services, mount /data and > restart all the main services. > > Unfortunately, on restart of those main services we observe : > > DisplayManager Could not get display information from display manager. > DisplayManager android.os.DeadObjectException > DisplayManager at android.os.BinderProxy.transact(Native Method) > DisplayManager at android.hardware.display.IDisplayManager$Stub$Proxy.getDisplayInfo(IDisplayManager.java:228) > DisplayManager at android.hardware.display.DisplayManagerGlobal.getDisplayInfo(DisplayManagerGlobal.java:117) > DisplayManager at android.hardware.display.DisplayManagerGlobal.getCompatibleDisplay(DisplayManagerGlobal.java:176) > DisplayManager at android.app.ResourcesManager.getDisplayMetricsLocked(ResourcesManager.java:96) > DisplayManager at android.app.ResourcesManager.getDisplayMetricsLocked(ResourcesManager.java:74) > [...] > > Which means that the 'display' service is registered into the service_manager > but point to a dead object (understand died process). This error is the first > one of a chain of missing "remote" objects causing the death of processes until > the system can recovery by itself a few seconds later. > > The binder driver allows a "process" to ask a notification when a particular > reference die. In that case, the binder driver associate a death object to this > reference. > > When the system_server process died, the file descriptor to the binder driver is > automatically released and the binder driver will walk all the references > associated to this process to unallocate them. When such a reference has a > death object associated it will execute a task to notify the death to the > previously register process usually the service_manager process. > > The bug is that this walk on all the references is broken due to an > unfornate refactoring made by the following patch : > > commit 008fa749e0fe5b2fffd20b7fe4891bb80d072c6a > Author: Mirsal Ennaime <mirsal@xxxxxxxxx> > Date: Tue Mar 12 11:41:59 2013 +0100 > > which break the loop if the current reference does not have a death object > instead of continuing to the next reference. As a consequence all the next > references will not be correctly unallocate and no death notification will be > sent for them. > > Signed-off-by: Jeremy Compostella <jeremy.compostella@xxxxxxxxx> > --- > drivers/staging/android/binder.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) Thanks, but this fix has already been submitted, and has been part of the Android kernel git tree for a while with the authorship of someone else, so I'll use that patch instead when applying it. greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
