Messages in this thread | | | Subject | Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64 | From | Peter Zijlstra <> | Date | Wed, 09 Dec 2009 19:22:52 +0100 |
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On Wed, 2009-12-09 at 10:11 -0800, Tony Luck wrote: > On Wed, Dec 9, 2009 at 12:52 AM, Luming Yu <luming.yu@gmail.com> wrote: > > Commenting out the change make -32 Lockdep kernel boot. > > > > Tony, please let me know whether you can reproduce.. > > Yes. Commenting this out makes the system bootable for me. > > > kernel/lockdep.c > > static int save_trace(struct stack_trace *trace) > > { > > trace->nr_entries = 0; > > trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; > > trace->entries = stack_trace + nr_stack_trace_entries; > > > > trace->skip = 3; > > > > save_stack_trace(trace); > > #if 0 > > > > /* > > * Some daft arches put -1 at the end to indicate its a full trace. > > * > > * <rant> this is buggy anyway, since it takes a whole extra entry so a > > * complete trace that maxes out the entries provided will be reported > > * as incomplete, friggin useless </rant> > > */ > > if (trace->entries[trace->nr_entries-1] == ULONG_MAX) > > trace->nr_entries--; > > #endif > > This happens because ia64 save_stack_trace() is currently an empty stub, so it > doesn't set trace->nr_entries. > > Options: > 1) Add trace->nr_entries = 1; to ia64 stub. > 2) Change the generic code to defend against an unexpected failure in > save_stack_trace() > > if (trace->nr_entries > 0 && > trace->entries[trace->nr_entries-1] == ULONG_MAX) > trace->nr_entries--; > 3) Delete the code in the "daft"[1] architectures, and drop this hunk > from the generic code.
I'm thinking 2 and 3 together sound like a plan :-)
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