Messages in this thread | | | Subject | Re: [RFC][PATCH 02/21] tracing: Reimplement log2 | From | Tom Zanussi <> | Date | Wed, 08 Feb 2017 14:25:08 -0600 |
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On Wed, 2017-02-08 at 15:13 -0500, Steven Rostedt wrote: > On Wed, 8 Feb 2017 11:24:58 -0600 > Tom Zanussi <tom.zanussi@linux.intel.com> wrote: > > > static void destroy_hist_field(struct hist_field *hist_field) > > { > > + unsigned int i; > > + > > + if (!hist_field) > > + return; > > + > > + for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++) > > + destroy_hist_field(hist_field->operands[i]); > > Recursive functions get me really nervous. What limits it? Is this user > defined? Perhaps we need to find a better way to handle this that's not > recursive, or at least put in a hard limit of the amount it can recurse. >
It's limited by the expression depth, which shouldn't be more than 1 deep, but you're right, there should be an explicit limit check, just in case - will add one.
Tom
> -- Steve > > > + > > kfree(hist_field); > > } > > > > @@ -377,7 +393,10 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field, > > } > > > > if (flags & HIST_FIELD_FL_LOG2) { > > + unsigned long fl = flags & ~HIST_FIELD_FL_LOG2; > > hist_field->fn = hist_field_log2; > > + hist_field->operands[0] = create_hist_field(field, fl); > > + hist_field->size = hist_field->operands[0]->size; > > goto out; > > } > > >
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