Re: [PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Tue, Apr 04, 2006 at 06:46:45PM +0900, Hyok S. Choi wrote:
> On Tuesday 04 April 2006 05:20 pm, Russell King wrote:
> > Why do you think you need such complexity?
> > 
> > cancel_rearming_delayed_work() will wait until the poll task has
> > completed and has been removed from the system.  It's explicitly
> > designed for work handlers which self-rearm.
> 
> Hmm.. Maybe you're right, because dcc_shutdown and dcc_startup, which
> are the only functions that initiate or stop the work, will never be
> called concurrently by different callers?

RTFD.  This behaviour _is_ documented.  Documentation/serial/driver:

  startup(port)
	Grab any interrupt resources and initialise any low level driver
	state.  Enable the port for reception.  It should not activate
	RTS nor DTR; this will be done via a separate call to set_mctrl.

	Locking: port_sem taken.
	Interrupts: globally disabled.

  shutdown(port)
	Disable the port, disable any break condition that may be in
	effect, and free any interrupt resources.  It should not disable
	RTS nor DTR; this will have already been done via a separate
	call to set_mctrl.

	Locking: port_sem taken.
	Interrupts: caller dependent.

If the port semaphore is taken prior to calling either function...

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core