diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2014-06-16 09:17:00 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-10 16:05:19 -0700 |
| commit | addd4672bb442b23d16f91c5bae866ba1f9ffd4c (patch) | |
| tree | fb21b770969a5d9aab7e1f85af837ee9c6a4a53b /drivers | |
| parent | 0733db91d06a555b3f85f0b4c958c8949ed22e1d (diff) | |
tty: Document locking for tty_port_open()
The tty lock is held when the tty driver's open method is called
(from the lone call-site, tty_open()). The call-tree audit [1] of
tty_port_open() is a closed graph of the callers of tty_port_open();
ie., all callers originate from only tty_open().
Of these callers, none drop the tty lock.
Also, document that 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_open()
tty_open()
tty->ops->open() --+
|
rs_open():arch/ia64/hp/sim/simserial.c
*line_open():arch/um/drivers/line.c
gdm_tty_open():drivers/staging/gdm724x/gdm_tty.c
fwtty_open():drivers/staging/fwserial/fwserial.c
acm_tty_open():drivers/usb/class/cdc-acm.c
serial_open():drivers/usb/serial/usb-serial.c
pti_tty_driver_open():drivers/misc/pti.c
ipoctal_open():drivers/ipack/devices/ipoctal.c
isicom_open():drivers/tty/isicom.c
dashtty_open():drivers/tty/metag_da.c
goldfish_tty_open():drivers/tty/goldfish.c
ehv_bc_tty_open():drivers/tty/ehv_bytechan.c
mxser_open():drivers/tty/mxser.c
kgdb_nmi_tty_open():drivers/tty/serial/kgdb_nmi.c
ifx_spi_open():drivers/tty/serial/ifx6x60.c
smd_tty_open():drivers/tty/serial/msm_smd_tty.c
ntty_open():drivers/tty/nozomi.c
capinc_tty_open():drivers/isdn/capi/capi.c
tpk_open():drivers/char/ttyprintk.c
sdio_uart_open():drivers/mmc/card/sdio_uart.c
rfcomm_tty_open():net/bluetooth/rfcomm/tty.c
|
+- tty_port_open()
* line_open() is the .open method for 2 um drivers
declared in ./arch/um/drivers/stdio_console.c and
in ./arch/um/drivers/ssl.c, and not called directly
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/tty_port.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c index bcc15f75646c..f4698696abae 100644 --- a/drivers/tty/tty_port.c +++ b/drivers/tty/tty_port.c @@ -572,6 +572,14 @@ int tty_port_install(struct tty_port *port, struct tty_driver *driver, } EXPORT_SYMBOL_GPL(tty_port_install); +/** + * tty_port_open + * + * Caller holds tty lock. + * + * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so + * tty and tty_port may have changed state (eg., may be hung up now) + */ int tty_port_open(struct tty_port *port, struct tty_struct *tty, struct file *filp) { |