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    USB: usbtmc: Fix RCU stall warning · 30fad76c
    Qiang.zhang authored
    rcu: INFO: rcu_preempt self-detected stall on CPU
    rcu:    1-...!: (2 ticks this GP) idle=d92/1/0x4000000000000000
            softirq=25390/25392 fqs=3
            (t=12164 jiffies g=31645 q=43226)
    rcu: rcu_preempt kthread starved for 12162 jiffies! g31645 f0x0
         RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
    rcu:    Unless rcu_preempt kthread gets sufficient CPU time,
            OOM is now expected behavior.
    rcu: RCU grace-period kthread stack dump:
    task:rcu_preempt     state:R  running task
    ...........
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: unknown status received: -71
    usbtmc 3-1:0.0: usb_submit_urb failed: -19
    
    The function usbtmc_interrupt() resubmits urbs when the error status
    of an urb is -EPROTO. In systems using the dummy_hcd usb controller
    this can result in endless interrupt loops when the usbtmc device is
    disconnected from the host system.
    
    Since host controller drivers already try to recover from transmission
    errors, there is no need to resubmit the urb or try other solutions
    to repair the error situation.
    
    In case of errors the INT pipe just stops to wait for further packets.
    
    Fixes: dbf3e7f6 ("Implement an ioctl to support the USMTMC-USB488 READ_STATUS_BYTE operation")
    Cc: stable@vger.kernel.org
    Reported-by: syzbot+e2eae5639e7203360018@syzkaller.appspotmail.com
    Signed-off-by: default avatarQiang.zhang <qiang.zhang@windriver.com>
    Acked-by: default avatarGuido Kiener <guido.kiener@rohde-schwarz.com>
    Link: https://lore.kernel.org/r/20210723004334.458930-1-qiang.zhang@windriver.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    30fad76c
usbtmc.c 60.8 KB