Messages in this thread | | | Date | Wed, 1 Oct 2008 09:54:19 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 6/6] ftrace: take advantage of variable length entries |
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* Steven Rostedt <rostedt@goodmis.org> wrote:
> > > struct trace_entry *entry = iter->ent; > > > - struct mmiotrace_map *m = &entry->field.mmiomap; > > > + struct mmiotrace_map *m = (struct mmiotrace_map *)entry; > > > > This is different style than above, missing the struct > > trace_mmiotrace_map intermediate step. Looks like a bug, > > since struct mmiotrace_map is not the first field in > > struct trace_mmiotrace_map. > > Crap! yes this is a bug. Thanks for pointing this out.
hm, there's a significant amount of type casts, see the grep below.
The ringbuffer becoming type-opaque has exactly these kinds of dangers, and as i suggested a few days ago, please think about a debug mode that stores the record type in the trace entry and validates it on extraction or something like that.
That might even be a robustness feature: the tracer should not crash if the trace buffer gets corrupted. ftrace had that invariant before, i think we should try to keep as many aspects of it as possible.
Ingo
-------------> ring_buffer.c: page = (struct buffer_page *)virt_to_page(addr); ring_buffer.c: cpu_buffer->reader_page = (struct buffer_page *)virt_to_page(addr); ring_buffer.c:static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); ring_buffer.c: page = (struct buffer_page *)virt_to_page(addr); trace_boot.c: struct trace_boot *field = (struct trace_boot *)entry; trace.c:static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu); trace.c:static DEFINE_PER_CPU(struct trace_array_cpu, max_data); trace.c: cont = (struct trace_field_cont *)ent; trace.c: struct ftrace_entry *field = (struct ftrace_entry *)entry; trace.c: (struct ctx_switch_entry *)entry; trace.c: struct special_entry *field = (struct special_entry *)entry; trace.c: struct stack_entry *field = (struct stack_entry *)entry; trace.c: struct print_entry *field = (struct print_entry *)entry; trace.c: struct ftrace_entry *field = (struct ftrace_entry *)entry; trace.c: (struct ctx_switch_entry *)entry; trace.c: struct special_entry *field = (struct special_entry *)entry; trace.c: struct stack_entry *field = (struct stack_entry *)entry; trace.c: struct print_entry *field = (struct print_entry *)entry; trace.c: struct ftrace_entry *field = (struct ftrace_entry *)entry; trace.c: (struct ctx_switch_entry *)entry; trace.c: struct special_entry *field = (struct special_entry *)entry; trace.c: struct print_entry *field = (struct print_entry *)entry; trace.c: struct ftrace_entry *field = (struct ftrace_entry *)entry; trace.c: (struct ctx_switch_entry *)entry; trace.c: struct special_entry *field = (struct special_entry *)entry; trace.c: struct ftrace_entry *field = (struct ftrace_entry *)entry; trace.c: (struct ctx_switch_entry *)entry; trace.c: struct special_entry *field = (struct special_entry *)entry; trace.c: struct seq_file *m = (struct seq_file *)file->private_data; trace.c: offsetof(struct trace_iterator, seq)); trace.c: offsetof(struct trace_iterator, seq)); trace_mmiotrace.c: (struct trace_mmiotrace_rw *)entry; trace_mmiotrace.c: struct mmiotrace_map *m = (struct mmiotrace_map *)entry; trace_mmiotrace.c: struct print_entry *print = (struct print_entry *)entry; trace_sched_wakeup.c:static void __wakeup_reset(struct trace_array *tr); trace_sysprof.c:static DEFINE_PER_CPU(struct hrtimer, stack_trace_hrtimer); trace_sysprof.c: stack = ((char *)regs + sizeof(struct pt_regs)); trace_sysprof.c: regs = (struct pt_regs *)current->thread.sp0 - 1;
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