[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH 17/30] tracing: Improve panic/die notifiers
On Wed 2022-04-27 19:49:11, Guilherme G. Piccoli wrote: > Currently the tracing dump_on_oops feature is implemented > through separate notifiers, one for die/oops and the other > for panic. With the addition of panic notifier "id", this > patch makes use of such "id" to unify both functions. > > It also comments the function and changes the priority of the > notifier blocks, in order they run early compared to other > notifiers, to prevent useless trace data (like the callback > names for the other notifiers). Finally, we also removed an > unnecessary header inclusion. > > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -9767,38 +9766,46 @@ static __init int tracer_init_tracefs(void) > > fs_initcall(tracer_init_tracefs); > > -static int trace_panic_handler(struct notifier_block *this, > - unsigned long event, void *unused) > +/* > + * The idea is to execute the following die/panic callback early, in order > + * to avoid showing irrelevant information in the trace (like other panic > + * notifier functions); we are the 2nd to run, after hung_task/rcu_stall > + * warnings get disabled (to prevent potential log flooding). > + */ > +static int trace_die_panic_handler(struct notifier_block *self, > + unsigned long ev, void *unused) > { > - if (ftrace_dump_on_oops) > + int do_dump; > + > + if (!ftrace_dump_on_oops) > + return NOTIFY_DONE; > + > + switch (ev) { > + case DIE_OOPS: > + do_dump = 1; > + break; > + case PANIC_NOTIFIER: > + do_dump = 1; > + break; DIE_OOPS and PANIC_NOTIFIER are from different enum. It feels like comparing apples with oranges here. IMHO, the proper way to unify the two notifiers is a check of the @self parameter. Something like: static int trace_die_panic_handler(struct notifier_block *self, unsigned long ev, void *unused) { if (self == trace_die_notifier && val != DIE_OOPS) goto out; ftrace_dump(ftrace_dump_on_oops); out: return NOTIFY_DONE; } Best Regards, Petr
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