On Fri, 16 Aug 2024 20:59:47 +0200 Jiri Olsa <olsajiri@xxxxxxxxx> wrote: > so far the only working solution I have is adding '__nullable' suffix > to argument name: > > diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h > index 9ea4c404bd4e..fc46f0b42741 100644 > --- a/include/trace/events/sched.h > +++ b/include/trace/events/sched.h > @@ -559,9 +559,9 @@ DEFINE_EVENT(sched_stat_runtime, sched_stat_runtime, > */ > TRACE_EVENT(sched_pi_setprio, > > - TP_PROTO(struct task_struct *tsk, struct task_struct *pi_task), > + TP_PROTO(struct task_struct *tsk, struct task_struct *pi_task__nullable), > > - TP_ARGS(tsk, pi_task), > + TP_ARGS(tsk, pi_task__nullable), > > TP_STRUCT__entry( > __array( char, comm, TASK_COMM_LEN ) > @@ -574,8 +574,8 @@ TRACE_EVENT(sched_pi_setprio, > memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN); > __entry->pid = tsk->pid; > __entry->oldprio = tsk->prio; > - __entry->newprio = pi_task ? > - min(tsk->normal_prio, pi_task->prio) : > + __entry->newprio = pi_task__nullable ? > + min(tsk->normal_prio, pi_task__nullable->prio) : > tsk->normal_prio; > /* XXX SCHED_DEADLINE bits missing */ > ), > > > now I'm trying to make work something like: > > diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h > index 9ea4c404bd4e..4e4aae2d5700 100644 > --- a/include/trace/events/sched.h > +++ b/include/trace/events/sched.h > @@ -559,9 +559,9 @@ DEFINE_EVENT(sched_stat_runtime, sched_stat_runtime, > */ > TRACE_EVENT(sched_pi_setprio, > > - TP_PROTO(struct task_struct *tsk, struct task_struct *pi_task), > + TP_PROTO(struct task_struct *tsk, struct task_struct *__nullable(pi_task)), > > - TP_ARGS(tsk, pi_task), > + TP_ARGS(tsk, __nullable(pi_task)), > > TP_STRUCT__entry( > __array( char, comm, TASK_COMM_LEN ) Hmm, that's really ugly though. Both versions. Now when Alexei said: > > > > > We cannot make all tracepoint pointers to be PTR_TRUSTED | PTR_MAYBE_NULL > > > > > by default, since it will break a bunch of progs. > > > > > Instead we can annotate this tracepoint arg as __nullable and > > > > > teach the verifier to recognize such special arguments of tracepoints. I'm not familiar with the verifier, so I don't know how the above is implemented, and why it would break a bunch of progs. If you had a macro around the parameter: TP_PROTO(struct task_struct *tsk, struct task_struct *__nullable(pi_task)), Could having that go through another macro pass in trace_events.h work? That is, could we associate the trace event with "nullable" parameters that could be stored someplace else for you? -- Steve
