Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
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- To: Tony Luck <tony.luck@xxxxxxxxx>
- Subject: Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
- Date: Wed, 09 Dec 2009 19:22:52 +0100
- Cc: Luming Yu <luming.yu@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, "linux-ia64@xxxxxxxxxxxxxxx" <linux-ia64@xxxxxxxxxxxxxxx>, "Yu, Fenghua" <fenghua.yu@xxxxxxxxx>, "Li, Shaohua" <shaohua.li@xxxxxxxxx>
- In-reply-to: <12c511ca0912091011g1d6308c4if7684adf9b0c5baf@xxxxxxxxxxxxxx>
- List-id: <linux-ia64.vger.kernel.org>
- References: <3877989d0908272018va6ee8f7n7ab2838fdf1b26e6@xxxxxxxxxxxxxx> <20090828062212.GB11552@xxxxxxx> <3877989d0912032329u7c05a761wfdd5c7000b43218d@xxxxxxxxxxxxxx> <4BDB13256095B24D9644F65379E604265C12@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <3877989d0912041919i458300d7ydce73cf77979dad3@xxxxxxxxxxxxxx> <3877989d0912062156v7ba2a192y726f45b550ba50e@xxxxxxxxxxxxxx> <12c511ca0912071335i1a805c2eudb6ecb8f726f6a80@xxxxxxxxxxxxxx> <3877989d0912080425o4bf9e2beuf573e47930fd707f@xxxxxxxxxxxxxx> <3877989d0912082245m3ee1ea14y3b3c8aca99e9f378@xxxxxxxxxxxxxx> <3877989d0912090052v79fdce6aqb507639143b5d71e@xxxxxxxxxxxxxx> <12c511ca0912091011g1d6308c4if7684adf9b0c5baf@xxxxxxxxxxxxxx>
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@xxxxxxxxx> 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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- References:
- [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- RE: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
- Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64
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