Re: [PATCH 2/2] mfd: wm8994-core: Don't use managed regulator bulk get API

From: Charles Keepax
Date: Thu Sep 15 2016 - 08:34:35 EST

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In reply to: Viresh Kumar: "[PATCH 2/2] mfd: wm8994-core: Don't use managed regulator bulk get API"
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On Thu, Sep 15, 2016 at 04:47:01PM +0530, Viresh Kumar wrote:
> The kernel WARNs and then crashes today if wm8994_device_init() fails
> after calling devm_regulator_bulk_get().
>
> That happens because there are multiple devices involved here and the
> order in which resources are freed isn't correct.
>
> The regulators are added as children of wm8994->dev.
> devm_regulator_bulk_get() receives wm8994->dev as the device, though it
> gets the same regulators which were added as children of wm8994->dev
> earlier.
>
> During failures, the children are removed first and the core eventually
> calls regulator_unregister() for them. As regulator_put() was never done
> for them (opposite of devm_regulator_bulk_get()), the kernel WARNs at
>
> WARN_ON(rdev->open_count);
>
> And eventually it crashes from debugfs_remove_recursive().
>
> --------x------------------x----------------
>
> wm8994 3-001a: Device is not a WM8994, ID is 0
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at /mnt/ssd/all/work/repos/devel/linux/drivers/regulator/core.c:4072 regulator_unregister+0xc8/0xd0
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-rc6-00154-g54fe84cbd50b #41
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> [<c010e24c>] (unwind_backtrace) from [<c010af38>] (show_stack+0x10/0x14)
> [<c010af38>] (show_stack) from [<c032a1c4>] (dump_stack+0x88/0x9c)
> [<c032a1c4>] (dump_stack) from [<c011a98c>] (__warn+0xe8/0x100)
> [<c011a98c>] (__warn) from [<c011aa54>] (warn_slowpath_null+0x20/0x28)
> [<c011aa54>] (warn_slowpath_null) from [<c0384a0c>] (regulator_unregister+0xc8/0xd0)
> [<c0384a0c>] (regulator_unregister) from [<c0406434>] (release_nodes+0x16c/0x1dc)
> [<c0406434>] (release_nodes) from [<c04039c4>] (__device_release_driver+0x8c/0x110)
> [<c04039c4>] (__device_release_driver) from [<c0403a64>] (device_release_driver+0x1c/0x28)
> [<c0403a64>] (device_release_driver) from [<c0402b24>] (bus_remove_device+0xd8/0x104)
> [<c0402b24>] (bus_remove_device) from [<c03ffcd8>] (device_del+0x10c/0x218)
> [<c03ffcd8>] (device_del) from [<c0404e4c>] (platform_device_del+0x1c/0x88)
> [<c0404e4c>] (platform_device_del) from [<c0404ec4>] (platform_device_unregister+0xc/0x20)
> [<c0404ec4>] (platform_device_unregister) from [<c0428bc0>] (mfd_remove_devices_fn+0x5c/0x64)
> [<c0428bc0>] (mfd_remove_devices_fn) from [<c03ff9d8>] (device_for_each_child_reverse+0x4c/0x78)
> [<c03ff9d8>] (device_for_each_child_reverse) from [<c04288c4>] (mfd_remove_devices+0x20/0x30)
> [<c04288c4>] (mfd_remove_devices) from [<c042758c>] (wm8994_device_init+0x2ac/0x7f0)
> [<c042758c>] (wm8994_device_init) from [<c04f14a8>] (i2c_device_probe+0x178/0x1fc)
> [<c04f14a8>] (i2c_device_probe) from [<c04036fc>] (driver_probe_device+0x214/0x2c0)
> [<c04036fc>] (driver_probe_device) from [<c0403854>] (__driver_attach+0xac/0xb0)
> [<c0403854>] (__driver_attach) from [<c0401a74>] (bus_for_each_dev+0x68/0x9c)
> [<c0401a74>] (bus_for_each_dev) from [<c0402cf0>] (bus_add_driver+0x1a0/0x218)
> [<c0402cf0>] (bus_add_driver) from [<c040406c>] (driver_register+0x78/0xf8)
> [<c040406c>] (driver_register) from [<c04f20a0>] (i2c_register_driver+0x34/0x84)
> [<c04f20a0>] (i2c_register_driver) from [<c01017d0>] (do_one_initcall+0x40/0x170)
> [<c01017d0>] (do_one_initcall) from [<c0a00dbc>] (kernel_init_freeable+0x15c/0x1fc)
> [<c0a00dbc>] (kernel_init_freeable) from [<c06e07b0>] (kernel_init+0x8/0x114)
> [<c06e07b0>] (kernel_init) from [<c0107978>] (ret_from_fork+0x14/0x3c)
> ---[ end trace 0919d3d0bc998260 ]---
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at /mnt/ssd/all/work/repos/devel/linux/drivers/regulator/core.c:4072 regulator_unregister+0xc8/0xd0
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.8.0-rc6-00154-g54fe84cbd50b #41
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> [<c010e24c>] (unwind_backtrace) from [<c010af38>] (show_stack+0x10/0x14)
> [<c010af38>] (show_stack) from [<c032a1c4>] (dump_stack+0x88/0x9c)
> [<c032a1c4>] (dump_stack) from [<c011a98c>] (__warn+0xe8/0x100)
> [<c011a98c>] (__warn) from [<c011aa54>] (warn_slowpath_null+0x20/0x28)
> [<c011aa54>] (warn_slowpath_null) from [<c0384a0c>] (regulator_unregister+0xc8/0xd0)
> [<c0384a0c>] (regulator_unregister) from [<c0406434>] (release_nodes+0x16c/0x1dc)
> [<c0406434>] (release_nodes) from [<c04039c4>] (__device_release_driver+0x8c/0x110)
> [<c04039c4>] (__device_release_driver) from [<c0403a64>] (device_release_driver+0x1c/0x28)
> [<c0403a64>] (device_release_driver) from [<c0402b24>] (bus_remove_device+0xd8/0x104)
> [<c0402b24>] (bus_remove_device) from [<c03ffcd8>] (device_del+0x10c/0x218)
> [<c03ffcd8>] (device_del) from [<c0404e4c>] (platform_device_del+0x1c/0x88)
> wm8994 3-001a: Device is not a WM8994, ID is 0
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at /mnt/ssd/all/work/repos/devel/linux/drivers/regulator/core.c:4072 regulator_unregister+0xc8/0xd0
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-rc6-00154-g54fe84cbd50b #41
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> [<c010e24c>] (unwind_backtrace) from [<c010af38>] (show_stack+0x10/0x14)
> [<c010af38>] (show_stack) from [<c032a1c4>] (dump_stack+0x88/0x9c)
> [<c032a1c4>] (dump_stack) from [<c011a98c>] (__warn+0xe8/0x100)
> [<c011a98c>] (__warn) from [<c011aa54>] (warn_slowpath_null+0x20/0x28)
> [<c011aa54>] (warn_slowpath_null) from [<c0384a0c>] (regulator_unregister+0xc8/0xd0)
> [<c0384a0c>] (regulator_unregister) from [<c0406434>] (release_nodes+0x16c/0x1dc)
> [<c0406434>] (release_nodes) from [<c04039c4>] (__device_release_driver+0x8c/0x110)
> [<c04039c4>] (__device_release_driver) from [<c0403a64>] (device_release_driver+0x1c/0x28)
> [<c0403a64>] (device_release_driver) from [<c0402b24>] (bus_remove_device+0xd8/0x104)
> [<c0402b24>] (bus_remove_device) from [<c03ffcd8>] (device_del+0x10c/0x218)
> [<c03ffcd8>] (device_del) from [<c0404e4c>] (platform_device_del+0x1c/0x88)
> [<c0404e4c>] (platform_device_del) from [<c0404ec4>] (platform_device_unregister+0xc/0x20)
> [<c0404ec4>] (platform_device_unregister) from [<c0428bc0>] (mfd_remove_devices_fn+0x5c/0x64)
> [<c0428bc0>] (mfd_remove_devices_fn) from [<c03ff9d8>] (device_for_each_child_reverse+0x4c/0x78)
> [<c03ff9d8>] (device_for_each_child_reverse) from [<c04288c4>] (mfd_remove_devices+0x20/0x30)
> [<c04288c4>] (mfd_remove_devices) from [<c042758c>] (wm8994_device_init+0x2ac/0x7f0)
> [<c042758c>] (wm8994_device_init) from [<c04f14a8>] (i2c_device_probe+0x178/0x1fc)
> [<c04f14a8>] (i2c_device_probe) from [<c04036fc>] (driver_probe_device+0x214/0x2c0)
> [<c04036fc>] (driver_probe_device) from [<c0403854>] (__driver_attach+0xac/0xb0)
> [<c0403854>] (__driver_attach) from [<c0401a74>] (bus_for_each_dev+0x68/0x9c)
> [<c0401a74>] (bus_for_each_dev) from [<c0402cf0>] (bus_add_driver+0x1a0/0x218)
> [<c0402cf0>] (bus_add_driver) from [<c040406c>] (driver_register+0x78/0xf8)
> [<c040406c>] (driver_register) from [<c04f20a0>] (i2c_register_driver+0x34/0x84)
> [<c04f20a0>] (i2c_register_driver) from [<c01017d0>] (do_one_initcall+0x40/0x170)
> [<c01017d0>] (do_one_initcall) from [<c0a00dbc>] (kernel_init_freeable+0x15c/0x1fc)
> [<c0a00dbc>] (kernel_init_freeable) from [<c06e07b0>] (kernel_init+0x8/0x114)
> [<c06e07b0>] (kernel_init) from [<c0107978>] (ret_from_fork+0x14/0x3c)
> ---[ end trace 0919d3d0bc998260 ]---
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at /mnt/ssd/all/work/repos/devel/linux/drivers/regulator/core.c:4072 regulator_unregister+0xc8/0xd0
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.8.0-rc6-00154-g54fe84cbd50b #41
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> [<c010e24c>] (unwind_backtrace) from [<c010af38>] (show_stack+0x10/0x14)
> [<c010af38>] (show_stack) from [<c032a1c4>] (dump_stack+0x88/0x9c)
> [<c032a1c4>] (dump_stack) from [<c011a98c>] (__warn+0xe8/0x100)
> [<c011a98c>] (__warn) from [<c011aa54>] (warn_slowpath_null+0x20/0x28)
> [<c011aa54>] (warn_slowpath_null) from [<c0384a0c>] (regulator_unregister+0xc8/0xd0)
> [<c0384a0c>] (regulator_unregister) from [<c0406434>] (release_nodes+0x16c/0x1dc)
> [<c0406434>] (release_nodes) from [<c04039c4>] (__device_release_driver+0x8c/0x110)
> [<c04039c4>] (__device_release_driver) from [<c0403a64>] (device_release_driver+0x1c/0x28)
> [<c0403a64>] (device_release_driver) from [<c0402b24>] (bus_remove_device+0xd8/0x104)
> [<c0402b24>] (bus_remove_device) from [<c03ffcd8>] (device_del+0x10c/0x218)
> [<c03ffcd8>] (device_del) from [<c0404e4c>] (platform_device_del+0x1c/0x88)
> [<c0404e4c>] (platform_device_del) from [<c0404ec4>] (platform_device_unregister+0xc/0x20)
> [<c0404ec4>] (platform_device_unregister) from [<c0428bc0>] (mfd_remove_devices_fn+0x5c/0x64)
> [<c0428bc0>] (mfd_remove_devices_fn) from [<c03ff9d8>] (device_for_each_child_reverse+0x4c/0x78)
> [<c03ff9d8>] (device_for_each_child_reverse) from [<c04288c4>] (mfd_remove_devices+0x20/0x30)
> [<c04288c4>] (mfd_remove_devices) from [<c042758c>] (wm8994_device_init+0x2ac/0x7f0)
> [<c042758c>] (wm8994_device_init) from [<c04f14a8>] (i2c_device_probe+0x178/0x1fc)
> [<c04f14a8>] (i2c_device_probe) from [<c04036fc>] (driver_probe_device+0x214/0x2c0)
> [<c04036fc>] (driver_probe_device) from [<c0403854>] (__driver_attach+0xac/0xb0)
> [<c0403854>] (__driver_attach) from [<c0401a74>] (bus_for_each_dev+0x68/0x9c)
> [<c0401a74>] (bus_for_each_dev) from [<c0402cf0>] (bus_add_driver+0x1a0/0x218)
> [<c0402cf0>] (bus_add_driver) from [<c040406c>] (driver_register+0x78/0xf8)
> [<c040406c>] (driver_register) from [<c04f20a0>] (i2c_register_driver+0x34/0x84)
> [<c04f20a0>] (i2c_register_driver) from [<c01017d0>] (do_one_initcall+0x40/0x170)
> [<c01017d0>] (do_one_initcall) from [<c0a00dbc>] (kernel_init_freeable+0x15c/0x1fc)
> [<c0a00dbc>] (kernel_init_freeable) from [<c06e07b0>] (kernel_init+0x8/0x114)
> [<c06e07b0>] (kernel_init) from [<c0107978>] (ret_from_fork+0x14/0x3c)
> ---[ end trace 0919d3d0bc998261 ]---
> Unable to handle kernel NULL pointer dereference at virtual address 00000078
> pgd = c0004000
> [00000078] *pgd=00000000
> Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.8.0-rc6-00154-g54fe84cbd50b #41
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> task: ee874000 task.stack: ee878000
> PC is at down_write+0x14/0x54
> LR is at debugfs_remove_recursive+0x30/0x150
> pc : [<c06e489c>] lr : [<c02e9954>] psr: 80000013
> sp : ee879e18 ip : 2e575000 fp : 00000000
> r10: 00000000 r9 : c0406004 r8 : ee46f428
> r7 : ee46f4ac r6 : ee46f478 r5 : ee46f428 r4 : 00000078
> r3 : ffff0001 r2 : 00000000 r1 : 00000001 r0 : 00000078
> Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
> Control: 10c5387d Table: 4000406a DAC: 00000051
> Process swapper/0 (pid: 1, stack limit = 0xee878210)
> Stack: (0xee879e18 to 0xee87a000)
> 9e00: ee216340 c02e9954
> 9e20: ee216340 ee12bc00 0000000d eea22220 ee879e58 c0382b78 c0b1505c ee216340
> 9e40: 0000000d c0382c1c ee216300 ee216200 0000000d c0406434 ee1e7c00 ee216700
> 9e60: eea22220 c0b81c0c c0b81c14 c0b22320 ffffffea 00000000 00000000 c04035d4
> 9e80: eea22220 c0b22320 eea22254 c0b2a950 c0b44000 000000d8 00000000 c0403854
> 9ea0: 00000000 c0b22320 c04037a8 c0401a74 ee97be74 eea153c0 c0b22320 ee16f480
> 9ec0: 00000000 c0402cf0 c08a5174 c0a1d3cc c0a34840 c0b22320 c0a1d3cc c0a34840
> 9ee0: c0b44000 c040406c c0b22304 c0a1d3cc c0a34840 c04f20a0 c0a5ff58 c0a1d3cc
> 9f00: c0a34840 c01017d0 c0b0ac18 ee879f18 c0b45fe8 c06e3f40 60000000 c0b095a0
> 9f20: 00000000 c0b095a0 efffca46 c0716b00 efffca42 c01350dc 0000cccd 00000000
> 9f40: c08cdb2c 00000000 00000006 00000006 c0b0957c efffc940 c0a5ff58 00000006
> 9f60: c0a34840 c0b44000 c0b44000 000000d8 c0a34848 c0a00dbc 00000006 00000006
> 9f80: 00000000 c0a005a0 00000000 c06e07a8 00000000 00000000 00000000 00000000
> 9fa0: 00000000 c06e07b0 00000000 c0107978 00000000 00000000 00000000 00000000
> 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 ffffffff ffffffff
> [<c06e489c>] (down_write) from [<c02e9954>] (debugfs_remove_recursive+0x30/0x150)
> [<c02e9954>] (debugfs_remove_recursive) from [<c0382b78>] (_regulator_put+0x24/0xac)
> [<c0382b78>] (_regulator_put) from [<c0382c1c>] (regulator_put+0x1c/0x2c)
> [<c0382c1c>] (regulator_put) from [<c0406434>] (release_nodes+0x16c/0x1dc)
> [<c0406434>] (release_nodes) from [<c04035d4>] (driver_probe_device+0xec/0x2c0)
> [<c04035d4>] (driver_probe_device) from [<c0403854>] (__driver_attach+0xac/0xb0)
> [<c0403854>] (__driver_attach) from [<c0401a74>] (bus_for_each_dev+0x68/0x9c)
> [<c0401a74>] (bus_for_each_dev) from [<c0402cf0>] (bus_add_driver+0x1a0/0x218)
> [<c0402cf0>] (bus_add_driver) from [<c040406c>] (driver_register+0x78/0xf8)
> [<c040406c>] (driver_register) from [<c04f20a0>] (i2c_register_driver+0x34/0x84)
> [<c04f20a0>] (i2c_register_driver) from [<c01017d0>] (do_one_initcall+0x40/0x170)
> [<c01017d0>] (do_one_initcall) from [<c0a00dbc>] (kernel_init_freeable+0x15c/0x1fc)
> [<c0a00dbc>] (kernel_init_freeable) from [<c06e07b0>] (kernel_init+0x8/0x114)
> [<c06e07b0>] (kernel_init) from [<c0107978>] (ret_from_fork+0x14/0x3c)
> Code: e1a04000 f590f000 e3a03001 e34f3fff (e1902f9f)
> ---[ end trace 0919d3d0bc998262 ]---
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>
> CPU1: stopping
> CPU: 1 PID: 0 Comm: swapper/1 Tainted: G D W 4.8.0-rc6-00154-g54fe84cbd50b #41
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> [<c010e24c>] (unwind_backtrace) from [<c010af38>] (show_stack+0x10/0x14)
> [<c010af38>] (show_stack) from [<c032a1c4>] (dump_stack+0x88/0x9c)
> [<c032a1c4>] (dump_stack) from [<c010d4f8>] (handle_IPI+0x198/0x1ac)
> [<c010d4f8>] (handle_IPI) from [<c01014e4>] (gic_handle_irq+0x94/0x98)
> [<c01014e4>] (gic_handle_irq) from [<c010ba0c>] (__irq_svc+0x6c/0xa8)
> Exception stack(0xee89ff88 to 0xee89ffd0)
> ff80: 00000001 00000000 00000000 c0113f40 ee89e000 c0b02454
> ffa0: 00000002 00000000 00000000 c0a65f88 c0b024c0 c0b024b8 00000000 ee89ffd8
> ffc0: c01083b8 c01083bc 60000013 ffffffff
> [<c010ba0c>] (__irq_svc) from [<c01083bc>] (arch_cpu_idle+0x38/0x3c)
> [<c01083bc>] (arch_cpu_idle) from [<c01531f0>] (cpu_startup_entry+0x1cc/0x250)
> [<c01531f0>] (cpu_startup_entry) from [<4010158c>] (0x4010158c)
> ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> [<c0404e4c>] (platform_device_del) from [<c0404ec4>] (platform_device_unregister+0xc/0x20)
> [<c0404ec4>] (platform_device_unregister) from [<c0428bc0>] (mfd_remove_devices_fn+0x5c/0x64)
> [<c0428bc0>] (mfd_remove_devices_fn) from [<c03ff9d8>] (device_for_each_child_reverse+0x4c/0x78)
> [<c03ff9d8>] (device_for_each_child_reverse) from [<c04288c4>] (mfd_remove_devices+0x20/0x30)
> [<c04288c4>] (mfd_remove_devices) from [<c042758c>] (wm8994_device_init+0x2ac/0x7f0)
> [<c042758c>] (wm8994_device_init) from [<c04f14a8>] (i2c_device_probe+0x178/0x1fc)
> [<c04f14a8>] (i2c_device_probe) from [<c04036fc>] (driver_probe_device+0x214/0x2c0)
> [<c04036fc>] (driver_probe_device) from [<c0403854>] (__driver_attach+0xac/0xb0)
> [<c0403854>] (__driver_attach) from [<c0401a74>] (bus_for_each_dev+0x68/0x9c)
> [<c0401a74>] (bus_for_each_dev) from [<c0402cf0>] (bus_add_driver+0x1a0/0x218)
> [<c0402cf0>] (bus_add_driver) from [<c040406c>] (driver_register+0x78/0xf8)
> [<c040406c>] (driver_register) from [<c04f20a0>] (i2c_register_driver+0x34/0x84)
> [<c04f20a0>] (i2c_register_driver) from [<c01017d0>] (do_one_initcall+0x40/0x170)
> [<c01017d0>] (do_one_initcall) from [<c0a00dbc>] (kernel_init_freeable+0x15c/0x1fc)
> [<c0a00dbc>] (kernel_init_freeable) from [<c06e07b0>] (kernel_init+0x8/0x114)
> [<c06e07b0>] (kernel_init) from [<c0107978>] (ret_from_fork+0x14/0x3c)
> ---[ end trace 0919d3d0bc998261 ]---
> Unable to handle kernel NULL pointer dereference at virtual address 00000078
> pgd = c0004000
> [00000078] *pgd=00000000
> Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.8.0-rc6-00154-g54fe84cbd50b #41
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> task: ee874000 task.stack: ee878000
> PC is at down_write+0x14/0x54
> LR is at debugfs_remove_recursive+0x30/0x150
> pc : [<c06e489c>] lr : [<c02e9954>] psr: 80000013
> sp : ee879e18 ip : 2e575000 fp : 00000000
> r10: 00000000 r9 : c0406004 r8 : ee46f428
> r7 : ee46f4ac r6 : ee46f478 r5 : ee46f428 r4 : 00000078
> r3 : ffff0001 r2 : 00000000 r1 : 00000001 r0 : 00000078
> Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
> Control: 10c5387d Table: 4000406a DAC: 00000051
> Process swapper/0 (pid: 1, stack limit = 0xee878210)
> Stack: (0xee879e18 to 0xee87a000)
> 9e00: ee216340 c02e9954
> 9e20: ee216340 ee12bc00 0000000d eea22220 ee879e58 c0382b78 c0b1505c ee216340
> 9e40: 0000000d c0382c1c ee216300 ee216200 0000000d c0406434 ee1e7c00 ee216700
> 9e60: eea22220 c0b81c0c c0b81c14 c0b22320 ffffffea 00000000 00000000 c04035d4
> 9e80: eea22220 c0b22320 eea22254 c0b2a950 c0b44000 000000d8 00000000 c0403854
> 9ea0: 00000000 c0b22320 c04037a8 c0401a74 ee97be74 eea153c0 c0b22320 ee16f480
> 9ec0: 00000000 c0402cf0 c08a5174 c0a1d3cc c0a34840 c0b22320 c0a1d3cc c0a34840
> 9ee0: c0b44000 c040406c c0b22304 c0a1d3cc c0a34840 c04f20a0 c0a5ff58 c0a1d3cc
> 9f00: c0a34840 c01017d0 c0b0ac18 ee879f18 c0b45fe8 c06e3f40 60000000 c0b095a0
> 9f20: 00000000 c0b095a0 efffca46 c0716b00 efffca42 c01350dc 0000cccd 00000000
> 9f40: c08cdb2c 00000000 00000006 00000006 c0b0957c efffc940 c0a5ff58 00000006
> 9f60: c0a34840 c0b44000 c0b44000 000000d8 c0a34848 c0a00dbc 00000006 00000006
> 9f80: 00000000 c0a005a0 00000000 c06e07a8 00000000 00000000 00000000 00000000
> 9fa0: 00000000 c06e07b0 00000000 c0107978 00000000 00000000 00000000 00000000
> 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 ffffffff ffffffff
> [<c06e489c>] (down_write) from [<c02e9954>] (debugfs_remove_recursive+0x30/0x150)
> [<c02e9954>] (debugfs_remove_recursive) from [<c0382b78>] (_regulator_put+0x24/0xac)
> [<c0382b78>] (_regulator_put) from [<c0382c1c>] (regulator_put+0x1c/0x2c)
> [<c0382c1c>] (regulator_put) from [<c0406434>] (release_nodes+0x16c/0x1dc)
> [<c0406434>] (release_nodes) from [<c04035d4>] (driver_probe_device+0xec/0x2c0)
> [<c04035d4>] (driver_probe_device) from [<c0403854>] (__driver_attach+0xac/0xb0)
> [<c0403854>] (__driver_attach) from [<c0401a74>] (bus_for_each_dev+0x68/0x9c)
> [<c0401a74>] (bus_for_each_dev) from [<c0402cf0>] (bus_add_driver+0x1a0/0x218)
> [<c0402cf0>] (bus_add_driver) from [<c040406c>] (driver_register+0x78/0xf8)
> [<c040406c>] (driver_register) from [<c04f20a0>] (i2c_register_driver+0x34/0x84)
> [<c04f20a0>] (i2c_register_driver) from [<c01017d0>] (do_one_initcall+0x40/0x170)
> [<c01017d0>] (do_one_initcall) from [<c0a00dbc>] (kernel_init_freeable+0x15c/0x1fc)
> [<c0a00dbc>] (kernel_init_freeable) from [<c06e07b0>] (kernel_init+0x8/0x114)
> [<c06e07b0>] (kernel_init) from [<c0107978>] (ret_from_fork+0x14/0x3c)
> Code: e1a04000 f590f000 e3a03001 e34f3fff (e1902f9f)
> ---[ end trace 0919d3d0bc998262 ]---
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>
> --------x------------------x----------------

Feels like we could get away with a little less of the dump in
the commit message.

>
> Fix the kernel warnings and crashes by moving away from managed
> regulator bulk get API by using regulator_bulk_get() and explicitly
> calling regulator_put() for all the supplies in exit paths.
>
> Tested on Exynos 5250, dual core ARM A15 machine.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> ---
> drivers/mfd/wm8994-core.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mfd/wm8994-core.c b/drivers/mfd/wm8994-core.c
> index 1e644aa53a2d..a232387b7783 100644
> --- a/drivers/mfd/wm8994-core.c
> +++ b/drivers/mfd/wm8994-core.c
> @@ -394,7 +394,7 @@ static int wm8994_device_init(struct wm8994 *wm8994, int irq)
> goto err;
> }
>
> - ret = devm_regulator_bulk_get(wm8994->dev, wm8994->num_supplies,
> + ret = regulator_bulk_get(wm8994->dev, wm8994->num_supplies,
> wm8994->supplies);

Would be nice to stick a comment in here just to say we don't
want to use devres as some of the supplies will be provided by
the MFDs children. Just incase someone is going through the code
later and decides it would be good to update this to use devres.

Otherwise all looks good to me.

Thanks,
Charles

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