On 07/30/2015 06:54 PM, John Ogness wrote:
> uart_write_wakeup() should be called without holding the port lock.
> Otherwise a possible recursive spinlock issue can occur, such as
> the following callchain:
> 
> 8250_core.c:serial8250_tx_chars() - called with port locked
>  serial_core.c:uart_write_wakeup()
>   tty_io.c:tty_wakeup()
>    st_core.c:st_tty_wakeup()
>     st_core.c:st_tx_wakeup()
>      st_core.c:st_int_write()
>       serial_core.c:uart_write() - locks port

NAK.

This is a bug in the N_TI_WL line discipline, specifically in the
st_tx_wakeup() function, which cannot perform the write synchronously.

This is a common line discipline bug, and typically fixed by performing
the wakeup operations from a kworker instead.

Regards,
Peter Hurley
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