Re: [PATCH V3] mfd: wm8994-core: Don't use managed regulator bulk get API
On 27-10-16, 10:14, Charles Keepax wrote: > 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. Not just that, even the code moved a version back. Sorry for the noise, the right version is sent now :( -- viresh
Re: [PATCH V3] mfd: wm8994-core: Don't use managed regulator bulk get API
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) > [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [] (show_stack) from [] (dump_stack+0x88/0x9c) > [] (dump_stack) from [] (__warn+0xe8/0x100) > [] (__warn) from [] (warn_slowpath_null+0x20/0x28) > [] (warn_slowpath_null) from [] > (regulator_unregister+0xc8/0xd0) > [] (regulator_unregister) from [] > (release_nodes+0x16c/0x1dc) > [] (release_nodes) from [] > (__device_release_driver+0x8c/0x110) > [] (__device_release_driver) from [] > (device_release_driver+0x1c/0x28) > [] (device_release_driver) from [] > (bus_remove_device+0xd8/0x104) > [] (bus_remove_device) from [] (device_del+0x10c/0x218) > [] (device_del) from [] (platform_device_del+0x1c/0x88) > [] (platform_device_del) from [] > (platform_device_unregister+0xc/0x20) > [] (platform_device_unregister) from [] > (mfd_remove_devices_fn+0x5c/0x64) > [] (mfd_remove_devices_fn) from [] > (device_for_each_child_reverse+0x4c/0x78) > [] (device_for_each_child_reverse) from [] > (mfd_remove_devices+0x20/0x30) > [] (mfd_remove_devices) from [] > (wm8994_device_init+0x2ac/0x7f0) > [] (wm8994_device_init) from [] > (i2c_device_probe+0x178/0x1fc) > [] (i2c_device_probe) from [] > (driver_probe_device+0x214/0x2c0) > [] (driver_probe_device) from [] > (__driver_attach+0xac/0xb0) > [] (__driver_attach) from [] (bus_for_each_dev+0x68/0x9c) > [] (bus_for_each_dev) from [] > (bus_add_driver+0x1a0/0x218) > [] (bus_add_driver) from [] (driver_register+0x78/0xf8) > [] (driver_register) from [] > (i2c_register_driver+0x34/0x84) > [] (i2c_register_driver) from [] > (do_one_initcall+0x40/0x170) > [] (do_one_initcall) from [] > (kernel_init_freeable+0x15c/0x1fc) > [] (kernel_init_freeable) from [] (kernel_init+0x8/0x114) > [] (kernel_init) from [] (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: GW > 4.8.0-rc6-00154-g54fe84cbd50b #41 > Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) > [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [] (show_stack) from [] (dump_stack+0x88/0x9c) > [] (dump_stack) from [] (__warn+0xe8/0x100) > [] (__warn) from [] (warn_slowpath_null+0x20/0x28) > [] (warn_slowpath_null) from [] > (regulator_unregister+0xc8/0xd0) > [] (regulator_unregister) from [] > (release_nodes+0x16c/0x1dc) > [] (release_nodes) from [] > (__device_release_driver+0x8c/0x110) > [] (__device_release_driver) from [] > (device_release_driver+0x1c/0x28) > [] (device_release_driver) from [] > (bus_remove_device+0xd8/0x104) > [] (bus_remove_device) from [] (device_del+0x10c/0x218) > [] (device_del) from [] (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) > [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [] (show_stack) from [] (dump_stack+0x88/0x9c) > [] (dump_stack) from [] (__warn+0xe8/0x100) > [] (__warn) from [] (warn_slowpath_null+0x20/0x28) > [] (warn_slowpath_null) from [] > (regulator_unregister+0xc8/0xd0) > [] (regulator_unregister) from [] > (release_nodes+0x16c/0x1dc) > [] (release_nodes) from [] > (__device_release_driver+0x8c/
[PATCH V3] mfd: wm8994-core: Don't use managed regulator bulk get API
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) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x88/0x9c) [] (dump_stack) from [] (__warn+0xe8/0x100) [] (__warn) from [] (warn_slowpath_null+0x20/0x28) [] (warn_slowpath_null) from [] (regulator_unregister+0xc8/0xd0) [] (regulator_unregister) from [] (release_nodes+0x16c/0x1dc) [] (release_nodes) from [] (__device_release_driver+0x8c/0x110) [] (__device_release_driver) from [] (device_release_driver+0x1c/0x28) [] (device_release_driver) from [] (bus_remove_device+0xd8/0x104) [] (bus_remove_device) from [] (device_del+0x10c/0x218) [] (device_del) from [] (platform_device_del+0x1c/0x88) [] (platform_device_del) from [] (platform_device_unregister+0xc/0x20) [] (platform_device_unregister) from [] (mfd_remove_devices_fn+0x5c/0x64) [] (mfd_remove_devices_fn) from [] (device_for_each_child_reverse+0x4c/0x78) [] (device_for_each_child_reverse) from [] (mfd_remove_devices+0x20/0x30) [] (mfd_remove_devices) from [] (wm8994_device_init+0x2ac/0x7f0) [] (wm8994_device_init) from [] (i2c_device_probe+0x178/0x1fc) [] (i2c_device_probe) from [] (driver_probe_device+0x214/0x2c0) [] (driver_probe_device) from [] (__driver_attach+0xac/0xb0) [] (__driver_attach) from [] (bus_for_each_dev+0x68/0x9c) [] (bus_for_each_dev) from [] (bus_add_driver+0x1a0/0x218) [] (bus_add_driver) from [] (driver_register+0x78/0xf8) [] (driver_register) from [] (i2c_register_driver+0x34/0x84) [] (i2c_register_driver) from [] (do_one_initcall+0x40/0x170) [] (do_one_initcall) from [] (kernel_init_freeable+0x15c/0x1fc) [] (kernel_init_freeable) from [] (kernel_init+0x8/0x114) [] (kernel_init) from [] (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: GW 4.8.0-rc6-00154-g54fe84cbd50b #41 Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x88/0x9c) [] (dump_stack) from [] (__warn+0xe8/0x100) [] (__warn) from [] (warn_slowpath_null+0x20/0x28) [] (warn_slowpath_null) from [] (regulator_unregister+0xc8/0xd0) [] (regulator_unregister) from [] (release_nodes+0x16c/0x1dc) [] (release_nodes) from [] (__device_release_driver+0x8c/0x110) [] (__device_release_driver) from [] (device_release_driver+0x1c/0x28) [] (device_release_driver) from [] (bus_remove_device+0xd8/0x104) [] (bus_remove_device) from [] (device_del+0x10c/0x218) [] (device_del) from [] (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) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x88/0x9c) [] (dump_stack) from [] (__warn+0xe8/0x100) [] (__warn) from [] (warn_slowpath_null+0x20/0x28) [] (warn_slowpath_null) from [] (regulator_unregister+0xc8/0xd0) [] (regulator_unregister) from [] (release_nodes+0x16c/0x1dc) [] (release_nodes) from [] (__device_release_driver+0x8c/0x110) [] (__device_release_driver) from [] (device_release_driver+0x1c/0x28) [] (device_release_driver) from [] (bus_remove_device+0xd8/0x104) [] (bus_remove_device) from [] (device_del+0x10c/0x218) [] (device_del) from [] (platform_device_del+0x1c/0x88) [] (platform_device_del) from [] (platform_device_unregister+0xc/0x20) [] (platform_device_unregister) fro
