Thomas Weißschuh <[email protected]> writes: > Reactors can be called from any context through tracepoints. > When developing reactors care needs to be taken to only call APIs which > are safe. As the tracepoints used during testing may not actually be > called from restrictive contexts lockdep may not be helpful. > > Add explicit overrides to help lockdep find invalid code patterns. > > The usage of LD_WAIT_FREE will trigger lockdep warnings in the panic > reactor. These are indeed valid warnings but they are out of scope for > RV and will instead be fixed by the printk subsystem. > > Signed-off-by: Thomas Weißschuh <[email protected]> > --- ... > void rv_react(struct rv_monitor *monitor, const char *msg, ...) > { > + static DEFINE_WAIT_OVERRIDE_MAP(rv_react_map, LD_WAIT_FREE); > va_list args; > > if (!rv_reacting_on() || !monitor->react) > @@ -487,7 +489,9 @@ void rv_react(struct rv_monitor *monitor, const char > *msg, ...) > > va_start(args, msg); > > + lock_map_acquire_try(&rv_react_map); > monitor->react(msg, args); > + lock_map_release(&rv_react_map); > > va_end(args); > }
The reactors are invoked in tracepoints' handlers, thus they must not trigger another tracepoint, otherwise we may be stuck in an infinite loop. (this is why preempt_enable_notrace() exists alongside preempt_enable()). I'm not familiar with the internal lockdep. But I think these would trigger trace_lock_acquire() and trace_lock_release(). Nam
