[PATCH for v3.15] usb: musb: Fix panic upon musb_am335x module removal
Ezequiel Garcia
ezequiel at vanguardiasur.com.ar
Sat Jun 14 05:59:02 PDT 2014
Hi Felipe,
On 20 May 01:55 PM, Ezequiel Garcia wrote:
> On 17 May 09:04 PM, Ezequiel Garcia wrote:
> > At probe time, the musb_am335x driver register its childs by
> > calling of_platform_populate(), which registers all childs in
> > the devicetree hierarchy recursively.
> >
> > On the other side, the driver's remove() function uses of_device_unregister()
> > to remove each child of musb_am335x's.
> >
> > However, when musb_dsps is loaded, its devices are attached to the musb_am335x
> > device as musb_am335x childs. Hence, musb_am335x remove() will attempt to
> > unregister the devices registered by musb_dsps, which produces a kernel panic.
> >
> > In other words, the childs in the "struct device" hierarchy are not the same
> > as the childs in the "devicetree" hierarchy.
> >
> > Ideally, we should enforce the removal of the devices registered by
> > musb_am335x *only*, instead of all its child devices. However, because of the
> > recursive nature of of_platform_populate, this doesn't seem possible.
> >
> > Therefore, as the only solution at hand, this commit disables musb_am335x
> > driver removal capability, preventing it from being ever removed. This was
> > originally suggested by Sebastian Siewior:
> >
> > https://www.mail-archive.com/linux-omap@vger.kernel.org/msg104946.html
> >
> > And for reference, here's the panic upon module removal:
> >
> > musb-hdrc musb-hdrc.0.auto: remove, state 4
> > usb usb1: USB disconnect, device number 1
> > musb-hdrc musb-hdrc.0.auto: USB bus 1 deregistered
> > Unable to handle kernel NULL pointer dereference at virtual address 0000008c
> > pgd = de11c000
> > [0000008c] *pgd=9e174831, *pte=00000000, *ppte=00000000
> > Internal error: Oops: 17 [#1] ARM
> > Modules linked in: musb_am335x(-) musb_dsps musb_hdrc usbcore usb_common
> > CPU: 0 PID: 623 Comm: modprobe Not tainted 3.15.0-rc4-00001-g24efd13 #69
> > task: de1b7500 ti: de122000 task.ti: de122000
> > PC is at am335x_shutdown+0x10/0x28
> > LR is at am335x_shutdown+0xc/0x28
> > pc : [<c0327798>] lr : [<c0327794>] psr: a0000013
> > sp : de123df8 ip : 00000004 fp : 00028f00
> > r10: 00000000 r9 : de122000 r8 : c000e6c4
> > r7 : de0e3c10 r6 : de0e3800 r5 : de624010 r4 : de1ec750
> > r3 : de0e3810 r2 : 00000000 r1 : 00000001 r0 : 00000000
> > Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
> > Control: 10c5387d Table: 9e11c019 DAC: 00000015
> > Process modprobe (pid: 623, stack limit = 0xde122240)
> > Stack: (0xde123df8 to 0xde124000)
> > 3de0: de0e3810 bf054488
> > 3e00: bf05444c de624010 60000013 bf043650 000012fc de624010 de0e3810 bf043a20
> > 3e20: de0e3810 bf04b240 c0635b88 c02ca37c c02ca364 c02c8db0 de1b7500 de0e3844
> > 3e40: de0e3810 c02c8e28 c0635b88 de02824c de0e3810 c02c884c de0e3800 de0e3810
> > 3e60: de0e3818 c02c5b20 bf05417c de0e3800 de0e3800 c0635b88 de0f2410 c02ca838
> > 3e80: bf05417c de0e3800 bf055438 c02ca8cc de0e3c10 bf054194 de0e3c10 c02ca37c
> > 3ea0: c02ca364 c02c8db0 de1b7500 de0e3c44 de0e3c10 c02c8e28 c0635b88 de02824c
> > 3ec0: de0e3c10 c02c884c de0e3c10 de0e3c10 de0e3c18 c02c5b20 de0e3c10 de0e3c10
> > 3ee0: 00000000 bf059000 a0000013 c02c5bc0 00000000 bf05900c de0e3c10 c02c5c48
> > 3f00: de0dd0c0 de1ec970 de0f2410 bf05929c de0f2444 bf05902c de0f2410 c02ca37c
> > 3f20: c02ca364 c02c8db0 bf05929c de0f2410 bf05929c c02c94c8 bf05929c 00000000
> > 3f40: 00000800 c02c8ab4 bf0592e0 c007fc40 c00dd820 6273756d 336d615f 00783533
> > 3f60: c064a0ac de1b7500 de122000 de1b7500 c000e590 00000001 c000e6c4 c0060160
> > 3f80: 00028e70 00028e70 00028ea4 00000081 60000010 00028e70 00028e70 00028ea4
> > 3fa0: 00000081 c000e500 00028e70 00028e70 00028ea4 00000800 becb59f8 00027608
> > 3fc0: 00028e70 00028e70 00028ea4 00000081 00000001 00000001 00000000 00028f00
> > 3fe0: b6e6b6f0 becb59d4 000160e8 b6e6b6fc 60000010 00028ea4 00000000 00000000
> > [<c0327798>] (am335x_shutdown) from [<bf054488>] (dsps_musb_exit+0x3c/0x4c [musb_dsps])
> > [<bf054488>] (dsps_musb_exit [musb_dsps]) from [<bf043650>] (musb_shutdown+0x80/0x90 [musb_hdrc])
> > [<bf043650>] (musb_shutdown [musb_hdrc]) from [<bf043a20>] (musb_remove+0x24/0x68 [musb_hdrc])
> > [<bf043a20>] (musb_remove [musb_hdrc]) from [<c02ca37c>] (platform_drv_remove+0x18/0x1c)
> > [<c02ca37c>] (platform_drv_remove) from [<c02c8db0>] (__device_release_driver+0x70/0xc8)
> > [<c02c8db0>] (__device_release_driver) from [<c02c8e28>] (device_release_driver+0x20/0x2c)
> > [<c02c8e28>] (device_release_driver) from [<c02c884c>] (bus_remove_device+0xdc/0x10c)
> > [<c02c884c>] (bus_remove_device) from [<c02c5b20>] (device_del+0x104/0x198)
> > [<c02c5b20>] (device_del) from [<c02ca838>] (platform_device_del+0x14/0x9c)
> > [<c02ca838>] (platform_device_del) from [<c02ca8cc>] (platform_device_unregister+0xc/0x20)
> > [<c02ca8cc>] (platform_device_unregister) from [<bf054194>] (dsps_remove+0x18/0x38 [musb_dsps])
> > [<bf054194>] (dsps_remove [musb_dsps]) from [<c02ca37c>] (platform_drv_remove+0x18/0x1c)
> > [<c02ca37c>] (platform_drv_remove) from [<c02c8db0>] (__device_release_driver+0x70/0xc8)
> > [<c02c8db0>] (__device_release_driver) from [<c02c8e28>] (device_release_driver+0x20/0x2c)
> > [<c02c8e28>] (device_release_driver) from [<c02c884c>] (bus_remove_device+0xdc/0x10c)
> > [<c02c884c>] (bus_remove_device) from [<c02c5b20>] (device_del+0x104/0x198)
> > [<c02c5b20>] (device_del) from [<c02c5bc0>] (device_unregister+0xc/0x20)
> > [<c02c5bc0>] (device_unregister) from [<bf05900c>] (of_remove_populated_child+0xc/0x14 [musb_am335x])
> > [<bf05900c>] (of_remove_populated_child [musb_am335x]) from [<c02c5c48>] (device_for_each_child+0x44/0x70)
> > [<c02c5c48>] (device_for_each_child) from [<bf05902c>] (am335x_child_remove+0x18/0x30 [musb_am335x])
> > [<bf05902c>] (am335x_child_remove [musb_am335x]) from [<c02ca37c>] (platform_drv_remove+0x18/0x1c)
> > [<c02ca37c>] (platform_drv_remove) from [<c02c8db0>] (__device_release_driver+0x70/0xc8)
> > [<c02c8db0>] (__device_release_driver) from [<c02c94c8>] (driver_detach+0xb4/0xb8)
> > [<c02c94c8>] (driver_detach) from [<c02c8ab4>] (bus_remove_driver+0x4c/0xa0)
> > [<c02c8ab4>] (bus_remove_driver) from [<c007fc40>] (SyS_delete_module+0x128/0x1cc)
> > [<c007fc40>] (SyS_delete_module) from [<c000e500>] (ret_fast_syscall+0x0/0x48)
> >
> > Fixes: 97238b35d5bb ("usb: musb: dsps: use proper child nodes")
> > Cc: <stable at vger.kernel.org> # v3.12+
> > Acked-by: George Cherian <george.cherian at ti.com>
> > Signed-off-by: Ezequiel Garcia <ezequiel at vanguardiasur.com.ar>
> > ---
> > drivers/usb/musb/musb_am335x.c | 23 ++++++-----------------
> > 1 file changed, 6 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/usb/musb/musb_am335x.c b/drivers/usb/musb/musb_am335x.c
> > index d235378..1e58ed2 100644
> > --- a/drivers/usb/musb/musb_am335x.c
> > +++ b/drivers/usb/musb/musb_am335x.c
> > @@ -19,21 +19,6 @@ err:
> > return ret;
> > }
> >
> > -static int of_remove_populated_child(struct device *dev, void *d)
> > -{
> > - struct platform_device *pdev = to_platform_device(dev);
> > -
> > - of_device_unregister(pdev);
> > - return 0;
> > -}
> > -
> > -static int am335x_child_remove(struct platform_device *pdev)
> > -{
> > - device_for_each_child(&pdev->dev, NULL, of_remove_populated_child);
> > - pm_runtime_disable(&pdev->dev);
> > - return 0;
> > -}
> > -
> > static const struct of_device_id am335x_child_of_match[] = {
> > { .compatible = "ti,am33xx-usb" },
> > { },
> > @@ -42,13 +27,17 @@ MODULE_DEVICE_TABLE(of, am335x_child_of_match);
> >
> > static struct platform_driver am335x_child_driver = {
> > .probe = am335x_child_probe,
> > - .remove = am335x_child_remove,
> > .driver = {
> > .name = "am335x-usb-childs",
> > .of_match_table = am335x_child_of_match,
> > },
> > };
> >
> > -module_platform_driver(am335x_child_driver);
> > +static int __init am335x_child_init(void)
> > +{
> > + return platform_driver_register(&am335x_child_driver);
> > +}
> > +module_init(am335x_child_init);
> > +
> > MODULE_DESCRIPTION("AM33xx child devices");
> > MODULE_LICENSE("GPL v2");
> > --
> > 1.9.1
> >
>
> Felipe,
>
> Any comments on this?
>
Any comments on this? I don't like to remove a feature, but as
explained above, I don't see any other way to solve this.
The driver is currently broken. I tried using of_platform_depopulate()
but failed.
--
Ezequiel Garcia, VanguardiaSur
www.vanguardiasur.com.ar
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