Re: Documentation for CPU hotplug support

[Chris Wright]

* Andrew Morton (akpm@xxxxxxxx) wrote:
> Nathan Lynch <nathanl@xxxxxxxxxxxxxx> wrote:
> >
> >  Argh, no.  That current_in_cpuhotplug hack has to go.
> 
> Yes, Ashok is busily working on removing that ;)

That's nice.  As it is, it deadlocks on boot:

cpufreq_stats_init
  lock_cpu_hotplug
  cpufreq_stat_cpu_callback
  ... (trace below)
  cpufreq_governor_performance
  __cpufreq_driver_target
  lock_cpu_hotplug  <-- uh-oh

SysRq : Show State

                                               sibling
  task             PC      pid father child younger older
swapper       D 003D08BC   764     1      0     2 			(L-TLB)
       eff8ed78 ef832030 c184a5f0 003d08bc effc5180 000000d0 df810b00 003d08bc
       00000002 ef832030 c184a5a0 00000000 df810b00 003d08bc ef832030 eff8dab0
       eff8dbd8 c0637140 c0637148 00000282 eff8edb0 c058bad3 eff8dab0 00000001
Call Trace:
 [<c058bad3>] __down+0x76/0xde
 [<c058a4aa>] __down_failed+0xa/0x10
 [<c04609ef>] .text.lock.cpufreq+0xee/0x1ff
 [<c0461049>] cpufreq_governor_performance+0x5d/0x74
 [<c045ff1c>] __cpufreq_governor+0x70/0x106
 [<c04603d8>] __cpufreq_set_policy+0x214/0x2b9
 [<c04605db>] cpufreq_update_policy+0xca/0xf1
 [<c0460fd5>] cpufreq_stat_cpu_callback+0x27/0x3e
 [<c06f657d>] cpufreq_stats_init+0xf0/0x152
 [<c06d59c2>] do_initcalls+0x56/0xba
 [<c06d5a4a>] do_basic_setup+0x24/0x2a
 [<c01003cf>] init+0xb5/0x1fe
 [<c010148d>] kernel_thread_helper+0x5/0xb
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