• Mathieu Desnoyers's avatar
    Debugobjects transition check · a5d8e467
    Mathieu Desnoyers authored
    
    
    Implement a basic state machine checker in the debugobjects.
    
    This state machine checker detects races and inconsistencies within the "active"
    life of a debugobject. The checker only keeps track of the current state; all
    the state machine logic is kept at the object instance level.
    
    The checker works by adding a supplementary "unsigned int astate" field to the
    debug_obj structure. It keeps track of the current "active state" of the object.
    
    The only constraints that are imposed on the states by the debugobjects system
    is that:
    
    - activation of an object sets the current active state to 0,
    - deactivation of an object expects the current active state to be 0.
    
    For the rest of the states, the state mapping is determined by the specific
    object instance. Therefore, the logic keeping track of the state machine is
    within the specialized instance, without any need to know about it at the
    debugobject level.
    
    The current object active state is changed by calling:
    
    debug_object_active_state(addr, descr, expect, next)
    
    where "expect" is the expected state and "next" is the next state to move to if
    the expected state is found. A warning is generated if the expected is not
    found.
    Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
    Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
    CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
    CC: akpm@linux-foundation.org
    CC: mingo@elte.hu
    CC: laijs@cn.fujitsu.com
    CC: dipankar@in.ibm.com
    CC: josh@joshtriplett.org
    CC: dvhltc@us.ibm.com
    CC: niv@us.ibm.com
    CC: peterz@infradead.org
    CC: rostedt@goodmis.org
    CC: Valdis.Kletnieks@vt.edu
    CC: dhowells@redhat.com
    CC: eric.dumazet@gmail.com
    CC: Alexey Dobriyan <adobriyan@gmail.com>
    Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
    a5d8e467