Thomas,

I was seeing a bunch of scheduling while atomic backtraces from rc4-rt5
on my laptop:

Dec  2 17:50:56 localhost kernel: [ 1397.730931] Call Trace:
Dec  2 17:50:56 localhost kernel: [ 1397.730938]  [<ffffffff814d5006>] __schedule_bug+0x75/0x7a
Dec  2 17:50:56 localhost kernel: [ 1397.730943]  [<ffffffff814e8e4a>] __schedule+0x8a/0x505
Dec  2 17:50:56 localhost kernel: [ 1397.730947]  [<ffffffff814e96df>] schedule+0x75/0x91
Dec  2 17:50:56 localhost kernel: [ 1397.730951]  [<ffffffff814ea64e>] rt_spin_lock_slowlock+0x182/0x21e
Dec  2 17:50:56 localhost kernel: [ 1397.730954]  [<ffffffff814ea5d9>] ? rt_spin_lock_slowlock+0x10d/0x21e
Dec  2 17:50:56 localhost kernel: [ 1397.730961]  [<ffffffff81090477>] rt_spin_lock_fastlock.constprop.12+0x24/0x26
Dec  2 17:50:56 localhost kernel: [ 1397.730965]  [<ffffffff814eaabb>] rt_spin_lock+0x16/0x3d
Dec  2 17:50:56 localhost kernel: [ 1397.730969]  [<ffffffff812acbe3>] advance_transaction+0x31/0x141
Dec  2 17:50:56 localhost kernel: [ 1397.730972]  [<ffffffff812ad819>] acpi_ec_gpe_handler+0x3f/0xc0
Dec  2 17:50:56 localhost kernel: [ 1397.730977]  [<ffffffff812b862a>] acpi_ev_gpe_dispatch+0xc5/0x13e
Dec  2 17:50:56 localhost kernel: [ 1397.730983]  [<ffffffff812b8758>] acpi_ev_gpe_detect+0xb5/0x10d
Dec  2 17:50:56 localhost kernel: [ 1397.730987]  [<ffffffff810b5048>] ? irq_thread_fn+0x3a/0x3a
Dec  2 17:50:56 localhost kernel: [ 1397.730990]  [<ffffffff812b6d26>] acpi_ev_sci_xrupt_handler+0x22/0x2b
Dec  2 17:50:56 localhost kernel: [ 1397.730994]  [<ffffffff812a7a08>] acpi_irq+0x16/0x31
Dec  2 17:50:56 localhost kernel: [ 1397.730996]  [<ffffffff810b506d>] irq_forced_thread_fn+0x25/0x46
Dec  2 17:50:56 localhost kernel: [ 1397.730998]  [<ffffffff814eb566>] ? _raw_spin_unlock_irq+0x53/0x60
Dec  2 17:50:56 localhost kernel: [ 1397.731001]  [<ffffffff810b4f26>] irq_thread+0xa5/0x18d
Dec  2 17:50:56 localhost kernel: [ 1397.731003]  [<ffffffff810b4e81>] ? irq_finalize_oneshot+0x19/0x19
Dec  2 17:50:56 localhost kernel: [ 1397.731006]  [<ffffffff81077ad2>] kthread+0x99/0xa1
Dec  2 17:50:56 localhost kernel: [ 1397.731009]  [<ffffffff814eb8b8>] ? retint_restore_args+0x13/0x13
Dec  2 17:50:56 localhost kernel: [ 1397.731014]  [<ffffffff814f3984>] kernel_thread_helper+0x4/0x10
Dec  2 17:50:56 localhost kernel: [ 1397.731016]  [<ffffffff814eb8b8>] ? retint_restore_args+0x13/0x13
Dec  2 17:50:56 localhost kernel: [ 1397.731019]  [<ffffffff81077a39>] ? __init_kthread_worker+0x89/0x89
Dec  2 17:50:56 localhost kernel: [ 1397.731022]  [<ffffffff814f3980>] ? gs_change+0x13/0x13


The attached patch converts the ACPI Embedded Controller lock to a raw
spinlock. Boots and suspends/resumes with no backtraces (from this
anyway...let's not talk about nouveau right now...)

Clark