Re: [REGRESSION] "USB: use kfifo to buffer usb-generic serialwrites" causes gobi_loader to hang

[Johan Hovold]

> > The log shows no call to usb_serial_generic_write_room()
> > Do you consider this a bug in the tty layer?
> 
> Actually this all makes sense because of where it was hanging. A reply of
> 0 to the tty->ops->write will cause it to either return (O_NONBLOCK) or
> sleep in the n_tty write code waiting for a write_wait wakeup
> (tty_wakeup(tty))
> 
> So the fix does indeed look correct.

Is it really a fix? If the fifo is already full the write urb should be
in use and Oliver's patch would amount to only a minor optimisation as
usb_serial_generic_write_start would return 0 anyway.

/Johan

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