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    SubjectRe: Locking problem in usbserial with 2.6.23-git 5a34417f
    Jiri Kosina wrote:
    > On Fri, 19 Oct 2007, Larry Finger wrote:
    >> While attempting to configure a new USB modem, the following locking
    >> problem occurred. In addition, shortly after this problem occurred, the
    >> computer froze. The log data starts at the point that usbserial was
    >> loaded and contains everything that was written to disk before the
    >> machine locked up. Some info may be missing from the end of the stack
    >> dump.
    > I guess this one is needed.
    > From: Jiri Kosina <>
    > USB: usbserial - fix potential deadlock between write() and irq
    > usb_serial_generic_write() doesn't disable interrupts when taking port->lock,
    > and could therefore deadlock with usb_serial_generic_read_bulk_callback()
    > being called from interrupt, taking the same lock. Fix it.
    > Signed-off-by: Jiri Kosina <>

    As I said earlier, the lock problem went away; however, I get the following two kernel warnings:

    WARNING: at kernel/sched.c:3475 sub_preempt_count()

    Call Trace:
    [<ffffffff8022df50>] sub_preempt_count+0x7e/0x91
    [<ffffffff80237eb9>] local_bh_enable_ip+0x91/0xf5
    [<ffffffff803eaaa8>] _spin_unlock_bh+0x39/0x3e
    [<ffffffff88405409>] :ppp_generic:ppp_channel_push+0x72/0xad
    [<ffffffff88406528>] :ppp_generic:ppp_write+0x10f/0x121
    [<ffffffff8028f75d>] vfs_write+0xae/0x137
    [<ffffffff8028fcc6>] sys_write+0x47/0x70
    [<ffffffff8020c2fa>] tracesys+0xdc/0xe1

    PPP BSD Compression module registered
    PPP Deflate Compression module registered
    WARNING: at kernel/softirq.c:139 local_bh_enable()

    Call Trace:
    [<ffffffff80237d82>] local_bh_enable+0x8f/0x135
    [<ffffffff8038f9ec>] dev_queue_xmit+0x2a6/0x2d2
    [<ffffffff803ab2be>] ip_finish_output+0x221/0x24f
    [<ffffffff803ab5d0>] ip_output+0x53/0x55
    [<ffffffff803a9df5>] ip_push_pending_frames+0x309/0x3ed
    [<ffffffff803c5f88>] udp_push_pending_frames+0x2d7/0x33f
    [<ffffffff803c70e9>] udp_sendmsg+0x4d5/0x61d
    [<ffffffff80248c99>] lock_hrtimer_base+0x25/0x4a
    [<ffffffff803cccce>] inet_sendmsg+0x46/0x53
    [<ffffffff80381ca3>] sock_sendmsg+0xdf/0xf8
    [<ffffffff80248e8f>] hrtimer_start+0x102/0x114
    [<ffffffff8024653c>] autoremove_wake_function+0x0/0x38
    [<ffffffff8020bb85>] do_notify_resume+0x68e/0x7ac
    [<ffffffff803ea5cb>] trace_hardirqs_on_thunk+0x35/0x3a
    [<ffffffff803826b4>] move_addr_to_kernel+0x40/0x49
    [<ffffffff803827db>] sys_sendto+0x11e/0x143
    [<ffffffff8020bf5d>] sys_rt_sigreturn+0x2a6/0x389
    [<ffffffff80265072>] audit_syscall_entry+0x148/0x17e
    [<ffffffff8020c2fa>] tracesys+0xdc/0xe1

    The second is complaining that interrupts are disabled, and may be related.

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      Last update: 2007-10-19 23:39    [W:0.022 / U:30.004 seconds]
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