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@xxxxxxxxxxxxxxxxxx>
---
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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