deadlock

Deadlock

Deadlock is a debugging tool that monitors the Intuition and Graphics locking
system to detect which process caused a GUI deadlock.

It patches follwoing functions in:

    intuition.library

    * LockIBase()
    * LockLayerInfo()
    * LockLayer()
    * LockLayers()
    * LockScreenList()
    * LockPubScreenList()
    * LockWindowList()
    * LockGadgetList()

    graphics.library

    * LockLayerInfo()
    * LockLayer()
    * LockLayers()

    Lock activity is tracked per PID.

    If the system freezes without a Guru (no input, no redraw, no window
movement), Deadlock can identify the task still holding a lock.

Installation

    Deadlock must be started before Workbench is loaded.
    Place it just before LoadWB in S:Startup-Sequence.
    To allow debugging after a freeze, add this to S:User-Startup:

    NewShell AUX:

    This creates a serial console so you can connect after the machine locks up.

Usage

    Use DeadLockCtrl to control the monitor:

    DeadLockCtrl LIST   ; list current locks per PID
    DeadLockCtrl QUIT   ; disable Deadlock

    If a deadlock occurs:

    Connect via the serial console.

    Run "DeadLockCtrl LIST" from putty/windows or picocom/linux

    Identify the PID still holding a lock.

    Run:

    FrozenAt PID=???

    If the binary is not stripped, the stack trace will usually reveal the
offending function.

    Send the stack trace to the program’s author.