On Fri, Dec 09, 2016 at 02:12:02PM +0900, Byungchul Park wrote: > Currently, save_trace() always performs save_stack_trace() for the > current. However, crossrelease needs to use stack trace data of another > context instead of the current. So add a parameter for skipping stack > tracing of the current and make it use trace data, which is already > saved by crossrelease framework. > > Signed-off-by: Byungchul Park <[email protected]> > --- > kernel/locking/lockdep.c | 33 ++++++++++++++++++++------------- > 1 file changed, 20 insertions(+), 13 deletions(-) > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > index 3eaa11c..11580ec 100644 > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -387,15 +387,22 @@ static void print_lockdep_off(const char *bug_msg) > #endif > } > > -static int save_trace(struct stack_trace *trace) > +static int save_trace(struct stack_trace *trace, int skip_tracing) > { > - trace->nr_entries = 0; > - trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; > - trace->entries = stack_trace + nr_stack_trace_entries; > + unsigned int nr_avail = MAX_STACK_TRACE_ENTRIES - > nr_stack_trace_entries; > > - trace->skip = 3; > - > - save_stack_trace(trace); > + if (skip_tracing) { > + trace->nr_entries = min(trace->nr_entries, nr_avail); > + memcpy(stack_trace + nr_stack_trace_entries, trace->entries, > + trace->nr_entries * sizeof(trace->entries[0])); > + trace->entries = stack_trace + nr_stack_trace_entries; > + } else { > + trace->nr_entries = 0; > + trace->max_entries = nr_avail; > + trace->entries = stack_trace + nr_stack_trace_entries; > + trace->skip = 3; > + save_stack_trace(trace); > + } > > /* > * Some daft arches put -1 at the end to indicate its a full trace.
That's pretty nasty semantics.. so when skip_tracing it modifies trace in-place.
