x86, x2apic: fix lock ordering during IRQ migration
Impact: fix potential deadlock on x2apic
fix "hard-safe -> hard-unsafe lock order detected" with irq_2_ir_lock
On x2apic enabled system:
[ INFO: hard-safe -> hard-unsafe lock order detected ]
2.6.27-03151-g4480f15b #1
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swapper/1 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
(irq_2_ir_lock){--..}, at: [<ffffffff8038ebc0>] get_irte+0x2f/0x95
and this task is already holding:
(&irq_desc_lock_class){+...}, at: [<ffffffff802649ed>] setup_irq+0x67/0x281
which would create a new lock dependency:
(&irq_desc_lock_class){+...} -> (irq_2_ir_lock){--..}
but this new dependency connects a hard-irq-safe lock:
(&irq_desc_lock_class){+...}
... which became hard-irq-safe at:
[<ffffffffffffffff>] 0xffffffffffffffff
to a hard-irq-unsafe lock:
(irq_2_ir_lock){--..}
... which became hard-irq-unsafe at:
... [<ffffffff802547b5>] __lock_acquire+0x571/0x706
[<ffffffff8025499f>] lock_acquire+0x55/0x71
[<ffffffff8062f2c4>] _spin_lock+0x2c/0x38
[<ffffffff8038ee50>] alloc_irte+0x8a/0x14b
[<ffffffff8021f733>] setup_IO_APIC_irq+0x119/0x30e
[<ffffffff8090860e>] setup_IO_APIC+0x146/0x6e5
[<ffffffff809058fc>] native_smp_prepare_cpus+0x24e/0x2e9
[<ffffffff808f982c>] kernel_init+0x5a/0x176
[<ffffffff8020c289>] child_rip+0xa/0x11
[<ffffffffffffffff>] 0xffffffffffffffff
Fix this theoretical lock order issue by using spin_lock_irqsave() instead of
spin_lock()
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
1 file changed