[RFC 8/9] tty: release tty lock when blocking

From: Arnd Bergmann
Date: Tue Mar 30 2010 - 16:57:18 EST

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From: Arnd Bergmann <arnd@xxxxxxxxxxxxxxxx>

All wait_event variants and work queue functions
that block on another thread need to release the
tty lock if the thread they are waiting on might
take it.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/char/cyclades.c | 4 ++--
drivers/char/istallion.c | 12 ++++++------
drivers/char/n_r3964.c | 2 +-
drivers/char/synclink.c | 2 ++
drivers/char/tty_buffer.c | 2 +-
drivers/char/tty_ioctl.c | 2 +-
drivers/char/tty_ldisc.c | 17 ++++++++++++++---
drivers/char/tty_port.c | 2 +-
drivers/char/vt_ioctl.c | 2 +-
drivers/serial/crisv10.c | 4 ++--
drivers/usb/class/cdc-acm.c | 2 +-
11 files changed, 32 insertions(+), 19 deletions(-)

diff --git a/drivers/char/cyclades.c b/drivers/char/cyclades.c
index 350595e..6dedc0c 100644
--- a/drivers/char/cyclades.c
+++ b/drivers/char/cyclades.c
@@ -1607,7 +1607,7 @@ static int cy_open(struct tty_struct *tty, struct file *filp)
* If the port is the middle of closing, bail out now
*/
if (tty_hung_up_p(filp) || (info->port.flags & ASYNC_CLOSING)) {
- wait_event_interruptible(info->port.close_wait,
+ wait_event_interruptible_tty(info->port.close_wait,
!(info->port.flags & ASYNC_CLOSING));
return (info->port.flags & ASYNC_HUP_NOTIFY) ? -EAGAIN: -ERESTARTSYS;
}
@@ -2780,7 +2780,7 @@ cy_ioctl(struct tty_struct *tty, struct file *file,
/* note the counters on entry */
cnow = info->icount;
spin_unlock_irqrestore(&info->card->card_lock, flags);
- ret_val = wait_event_interruptible(info->port.delta_msr_wait,
+ ret_val = wait_event_interruptible_tty(info->port.delta_msr_wait,
cy_cflags_changed(info, arg, &cnow));
break;

diff --git a/drivers/char/istallion.c b/drivers/char/istallion.c
index 39853b4..7c6728b 100644
--- a/drivers/char/istallion.c
+++ b/drivers/char/istallion.c
@@ -952,7 +952,7 @@ static int stli_rawopen(struct stlibrd *brdp, struct stliport *portp, unsigned l
* order of opens and closes may not be preserved across shared
* memory, so we must wait until it is complete.
*/
- wait_event_interruptible(portp->raw_wait,
+ wait_event_interruptible_tty(portp->raw_wait,
!test_bit(ST_CLOSING, &portp->state));
if (signal_pending(current)) {
return -ERESTARTSYS;
@@ -987,7 +987,7 @@ static int stli_rawopen(struct stlibrd *brdp, struct stliport *portp, unsigned l
set_bit(ST_OPENING, &portp->state);
spin_unlock_irqrestore(&brd_lock, flags);

- wait_event_interruptible(portp->raw_wait,
+ wait_event_interruptible_tty(portp->raw_wait,
!test_bit(ST_OPENING, &portp->state));
if (signal_pending(current))
rc = -ERESTARTSYS;
@@ -1018,7 +1018,7 @@ static int stli_rawclose(struct stlibrd *brdp, struct stliport *portp, unsigned
* occurs on this port.
*/
if (wait) {
- wait_event_interruptible(portp->raw_wait,
+ wait_event_interruptible_tty(portp->raw_wait,
!test_bit(ST_CLOSING, &portp->state));
if (signal_pending(current)) {
return -ERESTARTSYS;
@@ -1050,7 +1050,7 @@ static int stli_rawclose(struct stlibrd *brdp, struct stliport *portp, unsigned
* to come back.
*/
rc = 0;
- wait_event_interruptible(portp->raw_wait,
+ wait_event_interruptible_tty(portp->raw_wait,
!test_bit(ST_CLOSING, &portp->state));
if (signal_pending(current))
rc = -ERESTARTSYS;
@@ -1071,14 +1071,14 @@ static int stli_rawclose(struct stlibrd *brdp, struct stliport *portp, unsigned

static int stli_cmdwait(struct stlibrd *brdp, struct stliport *portp, unsigned long cmd, void *arg, int size, int copyback)
{
- wait_event_interruptible(portp->raw_wait,
+ wait_event_interruptible_tty(portp->raw_wait,
!test_bit(ST_CMDING, &portp->state));
if (signal_pending(current))
return -ERESTARTSYS;

stli_sendcmd(brdp, portp, cmd, arg, size, copyback);

- wait_event_interruptible(portp->raw_wait,
+ wait_event_interruptible_tty(portp->raw_wait,
!test_bit(ST_CMDING, &portp->state));
if (signal_pending(current))
return -ERESTARTSYS;
diff --git a/drivers/char/n_r3964.c b/drivers/char/n_r3964.c
index 2bd0e22..f771414 100644
--- a/drivers/char/n_r3964.c
+++ b/drivers/char/n_r3964.c
@@ -1079,7 +1079,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
goto unlock;
}
/* block until there is a message: */
- wait_event_interruptible(pInfo->read_wait,
+ wait_event_interruptible_tty(pInfo->read_wait,
(pMsg = remove_msg(pInfo, pClient)));
}

diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index c7af06b..c2252bd 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -2723,7 +2723,9 @@ static int mgsl_wait_event(struct mgsl_struct * info, int __user * mask_ptr)

for(;;) {
+ release_tty_lock(current);
schedule();
+ reacquire_tty_lock(current);
if (signal_pending(current)) {
rc = -ERESTARTSYS;
break;
diff --git a/drivers/char/tty_buffer.c b/drivers/char/tty_buffer.c
index 7ee5216..b532adc 100644
--- a/drivers/char/tty_buffer.c
+++ b/drivers/char/tty_buffer.c
@@ -143,7 +143,7 @@ void tty_buffer_flush(struct tty_struct *tty)
if (test_bit(TTY_FLUSHING, &tty->flags)) {
set_bit(TTY_FLUSHPENDING, &tty->flags);
spin_unlock_irqrestore(&tty->buf.lock, flags);
- wait_event(tty->read_wait,
+ wait_event_tty(tty->read_wait,
test_bit(TTY_FLUSHPENDING, &tty->flags) == 0);
return;
} else
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index c9b385e..06255bc 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -155,7 +155,7 @@ void tty_wait_until_sent(struct tty_struct *tty, long timeout)
#endif
if (!timeout)
timeout = MAX_SCHEDULE_TIMEOUT;
- if (wait_event_interruptible_timeout(tty->write_wait,
+ if (wait_event_interruptible_timeout_tty(tty->write_wait,
!tty_chars_in_buffer(tty), timeout) >= 0) {
if (tty->ops->wait_until_sent)
tty->ops->wait_until_sent(tty, timeout);
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 946ac05..759478d 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -331,8 +331,8 @@ struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
{
struct tty_ldisc *ld;

- /* wait_event is a macro */
- wait_event(tty_ldisc_wait, (ld = tty_ldisc_try(tty)) != NULL);
+ /* need to give up BTM when coming from paste_selection */
+ wait_event_tty(tty_ldisc_wait, (ld = tty_ldisc_try(tty)) != NULL);
return ld;
}
EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
@@ -525,8 +525,17 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)

static int tty_ldisc_halt(struct tty_struct *tty)
{
+ int ret;
clear_bit(TTY_LDISC, &tty->flags);
- return cancel_delayed_work_sync(&tty->buf.work);
+ if (tty_locked()) {
+ __release_tty_lock();
+ ret = cancel_delayed_work_sync(&tty->buf.work);
+ __reacquire_tty_lock();
+ } else {
+ ret = cancel_delayed_work_sync(&tty->buf.work);
+
+ }
+ return ret;
}

/**
@@ -852,7 +861,9 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
*/

tty_ldisc_halt(tty);
+ release_tty_lock(current);
flush_scheduled_work();
+ reacquire_tty_lock(current);

mutex_lock_tty_on(&tty->ldisc_mutex);
/*
diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 5ad1446..d78ef81 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -231,7 +231,7 @@ int tty_port_block_til_ready(struct tty_port *port,

/* block if port is in the process of being closed */
if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
- wait_event_interruptible(port->close_wait,
+ wait_event_interruptible_tty(port->close_wait,
!(port->flags & ASYNC_CLOSING));
if (port->flags & ASYNC_HUP_NOTIFY)
return -EAGAIN;
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index 0ebda0e..d54f73f 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -133,7 +133,7 @@ static void vt_event_wait(struct vt_event_wait *vw)
list_add(&vw->list, &vt_events);
spin_unlock_irqrestore(&vt_event_lock, flags);
/* Wait for it to pass */
- wait_event_interruptible(vt_event_waitqueue, vw->done);
+ wait_event_interruptible_tty(vt_event_waitqueue, vw->done);
/* Dequeue it */
spin_lock_irqsave(&vt_event_lock, flags);
list_del(&vw->list);
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index 0facf63..639d0ab 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3981,7 +3981,7 @@ block_til_ready(struct tty_struct *tty, struct file * filp,
*/
if (tty_hung_up_p(filp) ||
(info->flags & ASYNC_CLOSING)) {
- wait_event_interruptible(info->close_wait,
+ wait_event_interruptible_tty(info->close_wait,
!(info->flags & ASYNC_CLOSING));
#ifdef SERIAL_DO_RESTART
if (info->flags & ASYNC_HUP_NOTIFY)
@@ -4139,7 +4139,7 @@ rs_open(struct tty_struct *tty, struct file * filp)
*/
if (tty_hung_up_p(filp) ||
(info->flags & ASYNC_CLOSING)) {
- wait_event_interruptible(info->close_wait,
+ wait_event_interruptible_tty(info->close_wait,
!(info->flags & ASYNC_CLOSING));
#ifdef SERIAL_DO_RESTART
return ((info->flags & ASYNC_HUP_NOTIFY) ?
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index be6331e..a4abe2b 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -645,7 +645,7 @@ static void acm_port_down(struct acm *acm, int drain)
acm_set_control(acm, acm->ctrlout = 0);
/* try letting the last writes drain naturally */
if (drain) {
- wait_event_interruptible_timeout(acm->drain_wait,
+ wait_event_interruptible_timeout_tty(acm->drain_wait,
(ACM_NW == acm_wb_is_avail(acm)) || !acm->dev,
ACM_CLOSE_TIMEOUT * HZ);
}
--
1.7.0

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Next message: Arnd Bergmann: "[RFC 9/9] tty: implement BTM as mutex instead of BKL"
Previous message: Arnd Bergmann: "[RFC 5/9] tty: make ldisc_mutex nest under tty_lock"
In reply to: Arnd Bergmann: "[RFC 5/9] tty: make ldisc_mutex nest under tty_lock"
Next in thread: Arnd Bergmann: "[RFC 9/9] tty: implement BTM as mutex instead of BKL"
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