On Mon, 6 Apr 2015 14:36:16 +0900 Namhyung Kim <[email protected]> wrote:
> Currently it ignores operator priority and just sets processed args as a > right operand. But it could result in priority inversion in case that > the right operand is also a operator arg and its priority is lower. > > For example, following print format is from new kmem events. > > "page=%p", REC->pfn != -1UL ? (((struct page *)(0xffffea0000000000UL)) + > (REC->pfn)) : ((void *)0) > > But this was treated as below: > > REC->pfn != ((null - 1UL) ? ((struct page *)0xffffea0000000000UL + > REC->pfn) : (void *) 0) > > In this case, the right arg was '?' operator which has lower priority. > But it just sets the whole arg so making the output confusing - page was > always 0 or 1 since that's the result of logical operation. > > With this patch, it can handle it properly like following: > > ((REC->pfn != (null - 1UL)) ? ((struct page *)0xffffea0000000000UL + > REC->pfn) : (void *) 0) Nice catch. One nit. > > Cc: Steven Rostedt <[email protected]> > Signed-off-by: Namhyung Kim <[email protected]> > --- > tools/lib/traceevent/event-parse.c | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > diff --git a/tools/lib/traceevent/event-parse.c > b/tools/lib/traceevent/event-parse.c > index 6d31b6419d37..604bea5c3fb0 100644 > --- a/tools/lib/traceevent/event-parse.c > +++ b/tools/lib/traceevent/event-parse.c > @@ -1939,7 +1939,22 @@ process_op(struct event_format *event, struct > print_arg *arg, char **tok) > goto out_warn_free; > > type = process_arg_token(event, right, tok, type); > - arg->op.right = right; > + > + if (right->type == PRINT_OP && > + get_op_prio(arg->op.op) < get_op_prio(right->op.op)) { > + struct print_arg tmp; > + > + /* swap ops according to the priority */ This isn't really a swap. Better term to use is "rotate". But other than that, Acked-by: Steven Rostedt <[email protected]> -- Steve > + arg->op.right = right->op.left; > + > + tmp = *arg; > + *arg = *right; > + *right = tmp; > + > + arg->op.left = right; > + } else { > + arg->op.right = right; > + } > > } else if (strcmp(token, "[") == 0) { > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
