Fix up the tty-port initialized comments which got truncated and
obfuscated when replacing the old ASYNCB_INITIALIZED flag.

Fixes: d41861ca19c9 ("tty: Replace ASYNC_INITIALIZED bit and update atomically")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

For code neat purpose, we can use kmemdup to replace
kmalloc + memcpy.

Signed-off-by: Slark Xiao <slark_xiao@163.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

Replace symbolic permission macros with octal permission numbers
because octal permission numbers are easier to read and understand
instead of their symbolic macro names.

No functional change.

Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Utkarsh Verma <utkarshverma294@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

tty_operations::chars_in_buffer is being switched to return uint. Do the
same for usb_serial_driver's chars_in_buffer.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
[ johan: amend commit message ]
Signed-off-by: Johan Hovold <johan@kernel.org>

Line disciplines expect a positive value or zero returned from
tty->ops->write_room (invoked by tty_write_room). Both of them are being
updated to return an unsigned int. Switch also
usb_serial_driver::write_room and all its users.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
[ johan: amend commit message, drop unrelated comment change ]
Signed-off-by: Johan Hovold <johan@kernel.org>

All usb_serial drivers return 0 in their remove callbacks and driver
core ignores the value returned by usb_serial_device_remove(). So change
the remove callback to return void and return 0 unconditionally in
usb_serial_device_remove().

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20210208143149.963644-2-uwe@kleine-koenig.org
Signed-off-by: Johan Hovold <johan@kernel.org>

Clean up the handling of special interfaces that either should be
ignored or that need a larger number of URBs.

Commit 66f092ed3b94 ("USB: serial: sierra: unify quirk handling logic")
replaced the previous is_blacklisted() and is_highmemory() helpers with
a single is_quirk() helper which made it even harder to understand what
the interface lists were used for.

Rename the interface-list struct, its members and the interface-lookup
helper and restructure the code somewhat in order to make it more
self-explanatory.

Link: https://lore.kernel.org/r/20200713153936.18032-1-johan@kernel.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Drop redundant URB transfer-buffer casts.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

The sierra driver had two different functions for trying to determine
different quirks that did the same exact thing.  Remove one and rename
things to make it more obvious exactly what the different lists do.

Cc: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200618094300.1887727-6-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>