On Fri, Jul 15, 2016 at 10:45:36AM +0200, Oliver Neukum wrote: > On Fri, 2016-07-15 at 08:14 +0900, Greg KH wrote: > > Doh, nevermind, that's what I get for writing emails early in the > > morning while jet-lagged. > > > > Sorry for the noise, you are correct. > > No problem. Do you want me to resubmit? No need. I know a func-prefix is technically redundant, but the two alternatives are not equivalent in my opinion. I find the dev_dbg way of slapping the function name at the start of every debug message makes for unnecessarily hard-to-parse logs. Here's an example: [ 50.500823] tty ttyUSB0: serial_open [ 50.505401] ftdi_sio ttyUSB0: Setting CS8 [ 50.513275] ftdi_sio ttyUSB0: get_ftdi_divisor - tty_get_baud_rate reports speed 9600 [ 50.521728] ftdi_sio ttyUSB0: get_ftdi_divisor - Baud rate set to 9600 (divisor 0x4138) on chip FT232RL [ 50.532989] ftdi_sio ttyUSB0: ftdi_set_termios Turning off hardware flow control [ 50.543029] ftdi_sio ttyUSB0: update_mctrl - DTR HIGH, RTS HIGH [ 50.549926] tty ttyUSB0: serial_write_room [ 50.555328] ftdi_sio ttyUSB0: usb_serial_generic_write_room - returns 4096 [ 50.563354] tty ttyUSB0: serial_write - 3 byte(s) [ 50.569091] tty ttyUSB0: serial_write_room [ 50.574127] ftdi_sio ttyUSB0: usb_serial_generic_write_room - returns 4096 [ 50.582000] tty ttyUSB0: serial_write - 2 byte(s) [ 50.587799] tty ttyUSB0: serial_close [ 50.592468] tty ttyUSB0: serial_chars_in_buffer [ 50.597930] ftdi_sio ttyUSB0: usb_serial_generic_chars_in_buffer - returns 0 [ 50.605987] tty ttyUSB0: serial_wait_until_sent [ 50.611419] ftdi_sio ttyUSB0: usb_serial_generic_wait_until_sent - timeout = 30000 ms, period = 1 ms [ 50.622314] ftdi_sio ttyUSB0: ftdi_get_modem_status - 0x0160 [ 50.630096] ftdi_sio ttyUSB0: update_mctrl - DTR LOW, RTS LOW [ 50.640777] tty ttyUSB0: serial_cleanup Now with dev_dbg we instead get (with the %s and __func__ dropped): [ 116.419036] serial_open: tty ttyUSB0: serial_open [ 116.426849] ftdi_set_termios: ftdi_sio ttyUSB0: Setting CS8 [ 116.434295] get_ftdi_divisor: ftdi_sio ttyUSB0: tty_get_baud_rate reports speed 9600 [ 116.445037] get_ftdi_divisor: ftdi_sio ttyUSB0: Baud rate set to 9600 (divisor 0x4138) on chip FT232RL [ 116.457641] ftdi_set_termios: ftdi_sio ttyUSB0: Turning off hardware flow control [ 116.468780] update_mctrl: ftdi_sio ttyUSB0: DTR HIGH, RTS HIGH [ 116.476898] serial_write_room: tty ttyUSB0: [ 116.484039] usb_serial_generic_write_room: ftdi_sio ttyUSB0: returns 4096 [ 116.494812] serial_write: tty ttyUSB0: 3 byte(s) [ 116.501800] serial_write_room: tty ttyUSB0: [ 116.508697] usb_serial_generic_write_room: ftdi_sio ttyUSB0: returns 4096 [ 116.519470] serial_write: tty ttyUSB0: 2 byte(s) [ 116.526702] serial_close: tty ttyUSB0: [ 116.532257] serial_chars_in_buffer: tty ttyUSB0: [ 116.540039] usb_serial_generic_chars_in_buffer: ftdi_sio ttyUSB0: returns 0 [ 116.551452] serial_wait_until_sent: tty ttyUSB0: [ 116.559051] usb_serial_generic_wait_until_sent: ftdi_sio ttyUSB0: timeout = 30000 ms, period = 1 ms [ 116.573303] ftdi_get_modem_status: ftdi_sio ttyUSB0: 0x0160 [ 116.583282] update_mctrl: ftdi_sio ttyUSB0: DTR LOW, RTS LOW [ 116.595245] serial_cleanup: tty ttyUSB0: which I find much harder to parse. We don't always enforce a common prefix for function names, making grouping related functions even harder. Usually, what is printed in a debug message only makes sense in combination with the function name (e.g. serial_write: 2 bytes), but now that connection is also less clear. Also consider what the above log would look like if you have more than one device active. Trying to keep the independent traces separate by simply looking at the logs becomes almost impossible. For that reason I also very much prefer having the device name at the start of the message. Another reason is that the device names are of fixed length (for a device and usually class of devices), whereas functions names vary greatly and renders a more jagged "left column", after which device names and message follow. I should probably try to argue for the function-name to be moved in dev_dbg, but until that's at least been discussed further, I prefer to keep the (redundant) __func__s as they are. Thanks, Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
