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Date: Thu, 27 Oct 2016 10:14:13 +0100
From: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
CC: Lee Jones <lee.jones@linaro.org>, <linaro-kernel@lists.linaro.org>,
        <broonie@kernel.org>, <patches@opensource.wolfsonmicro.com>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V3] mfd: wm8994-core: Don't use managed regulator bulk
 get API
Message-ID: <20161027091413.GI28180@localhost.localdomain>
References: <ceb6ba8e70efae6f268295c0e04a4ca58c1f6d0b.1477539388.git.viresh.kumar@linaro.org>
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On Thu, Oct 27, 2016 at 09:09:30AM +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----------------

The back track seems to have got really really long again.

Thanks,
Charles

> 
>  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----------------
> 
> 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@linaro.org>
> Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
> ---
> V2->V3:
> - Fixed a rebase conflict
> - sending only one patch with Charles Ack
> 
> V1->V2:
> - Use regulator_bulk_free() instead of open coding it.
> - Shorter backtrace
> - Reworded the last paragraph to make it more clear
> - Added a comment in code
> 
>  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 95e6bc55adbb..87e9309c5f92 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);
>  	if (ret != 0) {
>  		dev_err(wm8994->dev, "Failed to get supplies: %d\n", ret);
> @@ -404,7 +404,7 @@ static int wm8994_device_init(struct wm8994 *wm8994, int irq)
>  	ret = regulator_bulk_enable(wm8994->num_supplies, wm8994->supplies);
>  	if (ret != 0) {
>  		dev_err(wm8994->dev, "Failed to enable supplies: %d\n", ret);
> -		goto err;
> +		goto err_regulator_put;
>  	}
>  
>  	ret = wm8994_reg_read(wm8994, WM8994_SOFTWARE_RESET);
> @@ -595,6 +595,9 @@ static int wm8994_device_init(struct wm8994 *wm8994, int irq)
>  err_enable:
>  	regulator_bulk_disable(wm8994->num_supplies,
>  			       wm8994->supplies);
> +err_regulator_put:
> +	for (i = wm8994->num_supplies - 1; i >= 0; i--)
> +		regulator_put(wm8994->supplies[i].consumer);
>  err:
>  	mfd_remove_devices(wm8994->dev);
>  	return ret;
> @@ -602,9 +605,12 @@ static int wm8994_device_init(struct wm8994 *wm8994, int irq)
>  
>  static void wm8994_device_exit(struct wm8994 *wm8994)
>  {
> +	int i;
>  	pm_runtime_disable(wm8994->dev);
>  	wm8994_irq_exit(wm8994);
>  	regulator_bulk_disable(wm8994->num_supplies, wm8994->supplies);
> +	for (i = wm8994->num_supplies - 1; i >= 0; i--)
> +		regulator_put(wm8994->supplies[i].consumer);
>  	mfd_remove_devices(wm8994->dev);
>  }
>  
> -- 
> 2.7.1.410.g6faf27b