On Tue, Mar 28, 2017 at 12:56:34PM -0500, Bin Liu wrote:
> On Tue, Mar 28, 2017 at 07:15:58PM +0200, Greg KH wrote:
> > On Tue, Mar 28, 2017 at 08:45:31AM -0500, Bin Liu wrote:
> > > commit bc1e2154542071e3cfe1734b143af9b8bdacf8bd upstream.
> > >
> > > The DSPS glue calls del_timer_sync() in its musb_platform_disable()
> > > implementation, which requires the caller to not hold a lock. But
> > > musb_remove() calls musb_platform_disable() will musb->lock held. This
> > > could causes spinlock deadlock.
> > >
> > > So change musb_remove() to call musb_platform_disable() without holds
> > > musb->lock. This doesn't impact the musb_platform_disable implementation
> > > in other glue drivers.
> > >
> > > root@am335x-evm:~# modprobe -r musb-dsps
> > > [ 126.134879] musb-hdrc musb-hdrc.1: remove, state 1
> > > [ 126.140465] usb usb2: USB disconnect, device number 1
> > > [ 126.146178] usb 2-1: USB disconnect, device number 2
> > > [ 126.416985] musb-hdrc musb-hdrc.1: USB bus 2 deregistered
> > > [ 126.423943]
> > > [ 126.425525] ======================================================
> > > [ 126.431997] [ INFO: possible circular locking dependency detected ]
> > > [ 126.438564] 4.11.0-rc1-00003-g1557f13bca04-dirty #77 Not tainted
> > > [ 126.444852] -------------------------------------------------------
> > > [ 126.451414] modprobe/778 is trying to acquire lock:
> > > [ 126.456523] (((&glue->timer))){+.-...}, at: [<c01b8788>] del_timer_sync+0x0/0xd0
> > > [ 126.464403]
> > > [ 126.464403] but task is already holding lock:
> > > [ 126.470511] (&(&musb->lock)->rlock){-.-...}, at: [<bf30b7f8>] musb_remove+0x50/0x1
> > > 30 [musb_hdrc]
> > > [ 126.479965]
> > > [ 126.479965] which lock already depends on the new lock.
> > > [ 126.479965]
> > > [ 126.488531]
> > > [ 126.488531] the existing dependency chain (in reverse order) is:
> > > [ 126.496368]
> > > [ 126.496368] -> #1 (&(&musb->lock)->rlock){-.-...}:
> > > [ 126.502968] otg_timer+0x80/0xec [musb_dsps]
> > > [ 126.507990] call_timer_fn+0xb4/0x390
> > > [ 126.512372] expire_timers+0xf0/0x1fc
> > > [ 126.516754] run_timer_softirq+0x80/0x178
> > > [ 126.521511] __do_softirq+0xc4/0x554
> > > [ 126.525802] irq_exit+0xe8/0x158
> > > [ 126.529735] __handle_domain_irq+0x58/0xb8
> > > [ 126.534583] __irq_usr+0x54/0x80
> > > [ 126.538507]
> > > [ 126.538507] -> #0 (((&glue->timer))){+.-...}:
> > > [ 126.544636] del_timer_sync+0x40/0xd0
> > > [ 126.549066] musb_remove+0x6c/0x130 [musb_hdrc]
> > > [ 126.554370] platform_drv_remove+0x24/0x3c
> > > [ 126.559206] device_release_driver_internal+0x14c/0x1e0
> > > [ 126.565225] bus_remove_device+0xd8/0x108
> > > [ 126.569970] device_del+0x1e4/0x308
> > > [ 126.574170] platform_device_del+0x24/0x8c
> > > [ 126.579006] platform_device_unregister+0xc/0x20
> > > [ 126.584394] dsps_remove+0x14/0x30 [musb_dsps]
> > > [ 126.589595] platform_drv_remove+0x24/0x3c
> > > [ 126.594432] device_release_driver_internal+0x14c/0x1e0
> > > [ 126.600450] driver_detach+0x38/0x6c
> > > [ 126.604740] bus_remove_driver+0x4c/0xa0
> > > [ 126.609407] SyS_delete_module+0x11c/0x1e4
> > > [ 126.614252] __sys_trace_return+0x0/0x10
> > >
> > > Fixes: ea2f35c01d5ea ("usb: musb: Fix sleeping function called from invalid context for hdrc glue")
> > > Cc: <stable@xxxxxxxxxxxxxxx> #4.9+
> > > Acked-by: Tony Lindgren <tony@xxxxxxxxxxx>
> > > Signed-off-by: Bin Liu <b-liu@xxxxxx>
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > >
> > > Conflicts:
> > > drivers/usb/musb/musb_core.c
> >
> > What is this "Conflicts:" line for?
>
> That was the reason the uptream commit failed to apply to stable
> automatically.
>
> I am not sure if we want to track it or not, so I leave it here for
> comment.
>
> Should I remove it?
Yes, please do. They do not belong in the changelog at all...
greg k-h