Messages in this thread Patch in this message |  | | From | Peter Hurley <> | Subject | [PATCH tty-next 04/22] tty: Document locking for tty_port_block_til_ready() | Date | Mon, 16 Jun 2014 09:17:01 -0400 |
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The tty lock is held when the tty driver's open() method is called (from tty_open()). The call-tree audit [1] of tty_port_block_til_ready() is a closed graph of the callers of tty_port_block_til_ready(); ie., all callers originate only from tty_open().
Of these callers, none drop the tty lock.
Also, document tty_port_block_til_ready() may drop and reacquire the tty lock when blocking, which means the tty or tty_port may have changed state.
[1] Call-tree audit of tty_port_block_til_ready() * does not include call tree of tty_port_open() which is already documented in 'tty: Document locking from tty_port_open()'
tty_open() tty->ops->open() --+ | cy_open():drivers/tty/cyclades.c rp_open():drivers/tty/rocket.c rs_open():drivers/tty/amiserial.c moxa_open():drivers/tty/moxa.c gsmtty_open():drivers/tty/n_gsm.c rs_open():drivers/tty/serial/68328serial.c uart_open():drivers/tty/serial/serial_core.c isdn_tty_open():drivers/isdn/i4l/isdn_tty.c mgslpc_open():drivers/char/pcmcia/synclink_cs.c | +- tty_port_block_til_ready()
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> --- drivers/tty/tty_port.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c index f469869..69e072b 100644 --- a/drivers/tty/tty_port.c +++ b/drivers/tty/tty_port.c @@ -348,6 +348,11 @@ EXPORT_SYMBOL(tty_port_lower_dtr_rts); * do carrier detect and the dtr_rts method if it supports software * management of these lines. Note that the dtr/rts raise is done each * iteration as a hangup may have previously dropped them while we wait. + * + * Caller holds tty lock. + * + * NB: May drop and reacquire tty lock when blocking, so tty and tty_port + * may have changed state (eg., may have been hung up). */ int tty_port_block_til_ready(struct tty_port *port, -- 2.0.0
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