• Bin Liu's avatar
    usb: musb: fix possible spinlock deadlock · bc1e2154
    Bin Liu authored
    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: ea2f35c0
    
     ("usb: musb: Fix sleeping function called from invalid context for hdrc glue")
    Cc: <stable@vger.kernel.org> #4.9+
    Acked-by: default avatarTony Lindgren <tony@atomide.com>
    Signed-off-by: default avatarBin Liu <b-liu@ti.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    bc1e2154