usb: serial: handle -EPROTO quietly in generic_read_bulk

If a USB serial device is unplugged while there is an active program
using the device it will spam the logs with -EPROTO (71) messages as it
attempts to retry.

Most serial usb drivers (metro-usb, pl2303, mos7840, ...) only output
these messages for debugging.  The generic driver treats these as
errors.

Change the default output for the generic serial driver from error to
debug.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
usb: serial: handle -ENODEV quietly in generic_submit_read_urb

If a USB serial device (e.g. /dev/ttyUSB0) with an active program is
unplugged, an -ENODEV (19) error will be produced after it gives up
trying to resubmit a read.

  usb_serial_generic_submit_read_urb - usb_submit_urb failed: -19

Add -ENODEV as one of the permanent errors along with -EPERM that
usb_serial_generic_submit_read_urb() handles quietly without an error.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: usbmon: fix wording "be reading until"

The usbmon documentation uses "be reading until" which is an uncommon
and confusing wording.  Change it to "read until it" which is more clear.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: usbmon: fix spelling s/unpriviledged/unprivileged/

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: fix wording, "is a", "built"

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: fix heading underlines and capitalization

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: "callsite" should be "call site"

The term "call site" consists of two words, not one.  In code "callsite"
might be an appropriate variable name, but not in documentation.  Fix
all instances in the dynamic debug documentation.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: remove obvious use of text utils

The dynamic debug documentation describes how the
<debugfs>/dynamic_debug/control file can be displayed using cat.
And then goes on to say that standard text utilities can be used.
It should be obvious to anyone who has used cat before that this
can be done, remove it.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: remove obvious spaces example

One example describes how commands can be sent to
<debugfs>/dynamic_debug/control with various combinations
 of tabs or spaces.  If the user sends a malformed command
it will be rejected, there is no need to describe this.
Remove these pointless examples.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: fix "A another" wording

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: remove obvious "cat file > control"

If a command can be echoed and redirected to the control file
it should be obvious that cat can be used to redirect a whole
file of these commands.  Remove this obvious example.

People reading this document want to know how to use
dynamic-debug, not how to use standard Linux utilities.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: fix plural "flags" usage

The plural "flags" was used incorrectly in several places, fix them.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: clean up nullarbor:~ # command examples

Many of the command line examples look they were copied straight
from a terminal and they are preceded with "nullarbor:~ #" which
is distracting.

Clean up the examples by removing the prefix, placing them on one
line where possible, and indenting them with two spaces.

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
doc: dynamic-debug: don't use C99 comments for examples

C99 comments are used in many of the examples even though they are not
allowed in Linux [1].  Change them to /* C89 style */.

The comment on line 165 was also shortened to fit withing 80 characters
by changing "yet another" to "another".

  [1]: linux/Documentation/CodingStyle

Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>