I get the following lockdump output on p2020rdb using
v3.10-rc5-43-g34376a5. While it's not particularly polite for the
esdhc driver to be calling OF functions while holding another lock which
can be acquired from interrupt context, why is devtree_lock usually
acquired in an irqsafe manner but sometimes not?
Both types of usage were added by the same commit:
commit d6d3c4e656513dcea61ce900f0ecb9ca820ee7cd
Author: Thomas Gleixner <t...@linutronix.de>
Date: Wed Feb 6 15:30:56 2013 -0500
OF: convert devtree lock from rw_lock to raw spinlock
Stephen, you asked about this here:
http://lkml.indiana.edu/hypermail/linux/kernel/1302.1/01383.html
Did you ever get an answer?
I'm also curious why devtree_lock was made raw to begin with...
Iterating over a device tree doesn't seem like something you'd want to
trust to be low-latency.
Here's the lockdep output:
sdhci: Secure Digital Host Controller Interface driver
sdhci: Copyright(c) Pierre Ossman
sdhci-pltfm: SDHCI platform and OF driver helper
mmc0: SDHCI controller on ffe2e000.sdhc [ffe2e000.sdhc] using DMA
=========================================================
[ INFO: possible irq lock inversion dependency detected ]
3.10.0-rc5-00043-g34376a5 #3 Not tainted
---------------------------------------------------------
swapper/0/0 just changed the state of lock:
(&(&host->lock)->rlock#2){-.....}, at: [<c049b7b8>] sdhci_irq+0x20/0xab8
but this lock took another, HARDIRQ-unsafe lock in the past:
(devtree_lock){+.+...}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(devtree_lock);
local_irq_disable();
lock(&(&host->lock)->rlock#2);
lock(devtree_lock);
<Interrupt>
lock(&(&host->lock)->rlock#2);
*** DEADLOCK ***
no locks held by swapper/0/0.
the shortest dependencies between 2nd lock and 1st lock:
-> (devtree_lock){+.+...} ops: 8177 {
HARDIRQ-ON-W at:
[<c00ac70c>] lock_acquire+0x4c/0x68
[<c0655a40>] _raw_spin_lock+0x44/0x60
[<c04bfd84>] of_find_node_by_phandle+0x28/0x74
[<c04c25e0>] of_irq_find_parent+0x38/0xb0
[<c04c2a58>] of_irq_map_one+0x7c/0xd8
[<c04c2ac8>] irq_of_parse_and_map+0x14/0x40
[<c04c2b14>] of_irq_to_resource+0x20/0xbc
[<c04c2c48>] of_irq_count+0x30/0x50
[<c04c349c>] of_device_alloc+0x14c/0x18c
[<c04c3534>]
of_platform_device_create_pdata+0x58/0x9c
[<c04c3670>] of_platform_bus_create+0xf8/0x1ac
[<c04c386c>] of_platform_bus_probe+0xa0/0xec
[<c0840e54>]
mpc85xx_common_publish_devices+0x20/0x30
[<c08422dc>]
__machine_initcall_p2020_rdb_pc_mpc85xx_common_publish_devices+0x2c/0x3c
[<c00021a4>] do_one_initcall+0x34/0x1a0
[<c083890c>] kernel_init_freeable+0x128/0x1d0
[<c0002970>] kernel_init+0x1c/0xfc
[<c000ec88>] ret_from_kernel_thread+0x5c/0x64
SOFTIRQ-ON-W at:
[<c00ac70c>] lock_acquire+0x4c/0x68
[<c0655a40>] _raw_spin_lock+0x44/0x60
[<c04bfd84>] of_find_node_by_phandle+0x28/0x74
[<c04c25e0>] of_irq_find_parent+0x38/0xb0
[<c04c2a58>] of_irq_map_one+0x7c/0xd8
[<c04c2ac8>] irq_of_parse_and_map+0x14/0x40
[<c04c2b14>] of_irq_to_resource+0x20/0xbc
[<c04c2c48>] of_irq_count+0x30/0x50
[<c04c349c>] of_device_alloc+0x14c/0x18c
[<c04c3534>]
of_platform_device_create_pdata+0x58/0x9c
[<c04c3670>] of_platform_bus_create+0xf8/0x1ac
[<c04c386c>] of_platform_bus_probe+0xa0/0xec
[<c0840e54>]
mpc85xx_common_publish_devices+0x20/0x30
[<c08422dc>]
__machine_initcall_p2020_rdb_pc_mpc85xx_common_publish_devices+0x2c/0x3c
[<c00021a4>] do_one_initcall+0x34/0x1a0
[<c083890c>] kernel_init_freeable+0x128/0x1d0
[<c0002970>] kernel_init+0x1c/0xfc
[<c000ec88>] ret_from_kernel_thread+0x5c/0x64
INITIAL USE at:
[<c00ac70c>] lock_acquire+0x4c/0x68
[<c0655ba0>] _raw_spin_lock_irqsave+0x58/0x78
[<c04bf714>] of_find_property+0x30/0x6c
[<c04bf890>] of_get_property+0x10/0x30
[<c04c10e4>] unflatten_dt_node+0x38c/0x528
[<c04c1334>] __unflatten_device_tree+0xb4/0x124
[<c085c924>] unflatten_device_tree+0x30/0x4c
[<c083c93c>] setup_arch+0x30/0x29c
[<c0838568>] start_kernel+0x90/0x30c
[<c00003fc>] skpinv+0x2e8/0x324
}
... key at: [<c08bd4b4>] devtree_lock+0x10/0x20
... acquired at:
[<c0655ba0>] _raw_spin_lock_irqsave+0x58/0x78
[<c04c0574>] of_find_compatible_node+0x38/0xfc
[<c049d8e4>] esdhc_of_set_clock+0x2c/0x224
[<c0498498>] sdhci_set_clock+0x60/0x428
[<c0498b44>] sdhci_do_set_ios+0xe0/0x6e4
[<c0485564>] mmc_power_up+0x88/0x130
[<c0487d50>] mmc_start_host+0x4c/0x8c
[<c04888d0>] mmc_add_host+0x58/0x78
[<c0499b40>] sdhci_add_host+0x7dc/0xaf4
[<c049d420>] sdhci_pltfm_register+0x38/0x60
[<c049d790>] sdhci_esdhc_probe+0x18/0x28
[<c0339294>] platform_drv_probe+0x20/0x30
[<c0337b2c>] driver_probe_device+0xa8/0x24c
[<c0337d94>] __driver_attach+0xc4/0xc8
[<c0335e2c>] bus_for_each_dev+0x80/0xbc
[<c03376e0>] driver_attach+0x24/0x34
[<c03371ac>] bus_add_driver+0x1f0/0x250
[<c03383f4>] driver_register+0x88/0x178
[<c03395ec>] platform_driver_register+0x68/0x78
[<c085b934>] sdhci_esdhc_driver_init+0x18/0x28
[<c00021a4>] do_one_initcall+0x34/0x1a0
[<c083890c>] kernel_init_freeable+0x128/0x1d0
[<c0002970>] kernel_init+0x1c/0xfc
[<c000ec88>] ret_from_kernel_thread+0x5c/0x64
-> (&(&host->lock)->rlock#2){-.....} ops: 4 {
IN-HARDIRQ-W at:
[<c00ac70c>] lock_acquire+0x4c/0x68
[<c0655a40>] _raw_spin_lock+0x44/0x60
[<c049b7b8>] sdhci_irq+0x20/0xab8
[<c00c0458>] handle_irq_event_percpu+0x74/0x1c8
[<c00c05f4>] handle_irq_event+0x48/0x78
[<c00c3c08>] handle_fasteoi_irq+0xd4/0x1c0
[<c000d588>] call_handle_irq+0x18/0x28
[<c0004b74>] do_IRQ+0x110/0x174
[<c000f20c>] ret_from_except+0x0/0x18
[<c00c86a0>] rcu_idle_enter+0xac/0xfc
[<c009b3d4>] cpu_startup_entry+0xd4/0x16c
[<c00028e0>] rest_init+0x110/0x184
[<c08387d0>] start_kernel+0x2f8/0x30c
[<c00003fc>] skpinv+0x2e8/0x324
INITIAL USE at:
[<c00ac70c>] lock_acquire+0x4c/0x68
[<c0655ba0>] _raw_spin_lock_irqsave+0x58/0x78
[<c0498a88>] sdhci_do_set_ios+0x24/0x6e4
[<c0485564>] mmc_power_up+0x88/0x130
[<c0487d50>] mmc_start_host+0x4c/0x8c
[<c04888d0>] mmc_add_host+0x58/0x78
[<c0499b40>] sdhci_add_host+0x7dc/0xaf4
[<c049d420>] sdhci_pltfm_register+0x38/0x60
[<c049d790>] sdhci_esdhc_probe+0x18/0x28
[<c0339294>] platform_drv_probe+0x20/0x30
[<c0337b2c>] driver_probe_device+0xa8/0x24c
[<c0337d94>] __driver_attach+0xc4/0xc8
[<c0335e2c>] bus_for_each_dev+0x80/0xbc
[<c03376e0>] driver_attach+0x24/0x34
[<c03371ac>] bus_add_driver+0x1f0/0x250
[<c03383f4>] driver_register+0x88/0x178
[<c03395ec>] platform_driver_register+0x68/0x78
[<c085b934>] sdhci_esdhc_driver_init+0x18/0x28
[<c00021a4>] do_one_initcall+0x34/0x1a0
[<c083890c>] kernel_init_freeable+0x128/0x1d0
[<c0002970>] kernel_init+0x1c/0xfc
[<c000ec88>] ret_from_kernel_thread+0x5c/0x64
}
... key at: [<c0dee0f0>] __key.24757+0x0/0x8
... acquired at:
[<c00aa198>] mark_lock+0x1fc/0x744
[<c00aae60>] __lock_acquire+0x780/0x1b6c
[<c00ac70c>] lock_acquire+0x4c/0x68
[<c0655a40>] _raw_spin_lock+0x44/0x60
[<c049b7b8>] sdhci_irq+0x20/0xab8
[<c00c0458>] handle_irq_event_percpu+0x74/0x1c8
[<c00c05f4>] handle_irq_event+0x48/0x78
[<c00c3c08>] handle_fasteoi_irq+0xd4/0x1c0
[<c000d588>] call_handle_irq+0x18/0x28
[<c0004b74>] do_IRQ+0x110/0x174
[<c000f20c>] ret_from_except+0x0/0x18
[<c00c86a0>] rcu_idle_enter+0xac/0xfc
[<c009b3d4>] cpu_startup_entry+0xd4/0x16c
[<c00028e0>] rest_init+0x110/0x184
[<c08387d0>] start_kernel+0x2f8/0x30c
[<c00003fc>] skpinv+0x2e8/0x324
stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.10.0-rc5-00043-g34376a5 #3
Call Trace:
[effe9d30] [c0007cb8] show_stack+0x44/0x154 (unreliable)
[effe9d70] [c065a224] dump_stack+0x24/0x34
[effe9d80] [c00a9250] print_irq_inversion_bug+0x204/0x264
[effe9db0] [c00a9340] check_usage_forwards+0x90/0x128
[effe9e00] [c00aa198] mark_lock+0x1fc/0x744
[effe9e30] [c00aae60] __lock_acquire+0x780/0x1b6c
[effe9ee0] [c00ac70c] lock_acquire+0x4c/0x68
[effe9f00] [c0655a40] _raw_spin_lock+0x44/0x60
[effe9f10] [c049b7b8] sdhci_irq+0x20/0xab8
[effe9f80] [c00c0458] handle_irq_event_percpu+0x74/0x1c8
[effe9fc0] [c00c05f4] handle_irq_event+0x48/0x78
[effe9fe0] [c00c3c08] handle_fasteoi_irq+0xd4/0x1c0
[effe9ff0] [c000d588] call_handle_irq+0x18/0x28
[c08cbe70] [c0004b74] do_IRQ+0x110/0x174
[c08cbea0] [c000f20c] ret_from_except+0x0/0x18
--- Exception: 501 at arch_cpu_idle+0x24/0x84
LR = arch_cpu_idle+0x24/0x84
[c08cbf60] [c00c86a0] rcu_idle_enter+0xac/0xfc (unreliable)
[c08cbf70] [c009b3d4] cpu_startup_entry+0xd4/0x16c
[c08cbfa0] [c00028e0] rest_init+0x110/0x184
[c08cbfc0] [c08387d0] start_kernel+0x2f8/0x30c
[c08cbff0] [c00003fc] skpinv+0x2e8/0x324
-Scott
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