* Jörn Engel <joern@logfs.org> wrote:

quoted text
> On Sun, 2 December 2007 09:56:08 +0100, Ingo Molnar wrote:
> > * Jörn Engel <joern@logfs.org> wrote:
> > 
> > > > ah. You should mark pit_read() function as notrace. PIT clocksource 
> > > > is rare. (add the 'notrace' word to the function prototype)
> > > 
> > > Hardly a change at all.  Apart from some offsets, this dump is 
> > > identical.
> > > 
> > > stopped custom tracer.
> > > BUG: spinlock recursion on CPU#0, sh/954
> > >  lock: c030f280, .magic: dead4ead, .owner: sh/954, .owner_cpu: 0
> > > Pid: 954, comm: sh Not tainted 2.6.24-rc3-ge1cca7e8-dirty #3
> > >  [<c0103a04>] show_trace_log_lvl+0x35/0x54
> > >  [<c010450a>] show_trace+0x2c/0x2e
> > >  [<c0104e6d>] dump_stack+0x84/0x8a
> > >  [<c01ded7c>] spin_bug+0xa7/0xae
> > >  [<c01def14>] _raw_spin_lock+0x45/0xfa
> > >  [<c02a02b1>] _spin_lock_irqsave+0x68/0x7a
> > >  [<c01087e2>] pit_read+0xf/0x91
> > >  [<c0130ee1>] get_monotonic_cycles+0xf/0x2d
> > >  [<c013c0e7>] now+0x2a/0x7c
> > >  [<c013c333>] ____trace+0x4d/0x1e8
> > >  [<c013dbeb>] __mcount+0x95/0xa6
> > >  [<c010d354>] mcount+0x14/0x18
> > >  [<c0135a3c>] lock_acquired+0xe/0x1d7
> > >  [<c02a02b9>] _spin_lock_irqsave+0x70/0x7a
> > >  [<c01087e2>] pit_read+0xf/0x91
> > 
> > hm, it seems lock_acquired() [in kernel/lockdep.c] needs to be marked 
> > 'notrace' too - otherwise we recurse back into pit_read().
> 
> This time not even the offsets have changed.  Dump is identical.

hm, do you have CONFIG_FRAME_POINTERS=y, i.e. are the dumps reliable?

	Ingo
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