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authorArnd Bergmann <arnd@arndb.de>2010-06-01 22:53:07 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-10 13:47:43 -0700
commit203652192634c1fce5e79df0a8ff2fabfaefd3ab (patch)
tree9c2ee78c04b0750220fa34e7adc541c16bf21e90 /drivers/serial
parent60af22d2ed490554cc92c8d0fed0b5b9cf687568 (diff)
downloadop-kernel-dev-203652192634c1fce5e79df0a8ff2fabfaefd3ab.zip
op-kernel-dev-203652192634c1fce5e79df0a8ff2fabfaefd3ab.tar.gz
tty: untangle locking of wait_until_sent
Some wait_until_sent versions require the big tty mutex, others don't and some callers of wait_until_sent already hold it while other don't. That leads to recursive use of the BTM in these functions, which we're trying to get rid of. This turns all cleans up the locking there so that the driver's wait_until_sent function never takes the BTM itself if it is already called with that lock held. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/serial')
-rw-r--r--drivers/serial/68360serial.c2
-rw-r--r--drivers/serial/crisv10.c2
-rw-r--r--drivers/serial/serial_core.c31
3 files changed, 22 insertions, 13 deletions
diff --git a/drivers/serial/68360serial.c b/drivers/serial/68360serial.c
index 16f5f2f..edcf1cc 100644
--- a/drivers/serial/68360serial.c
+++ b/drivers/serial/68360serial.c
@@ -1705,7 +1705,6 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
printk("jiff=%lu...", jiffies);
#endif
- tty_lock_nested(); /* always held already since we come from ->close */
/* We go through the loop at least once because we can't tell
* exactly when the last character exits the shifter. There can
* be at least two characters waiting to be sent after the buffers
@@ -1734,7 +1733,6 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
bdp--;
} while (bdp->status & BD_SC_READY);
current->state = TASK_RUNNING;
- tty_unlock();
#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
#endif
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index 94bfb9f..8e356c5 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3935,7 +3935,6 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
* Check R_DMA_CHx_STATUS bit 0-6=number of available bytes in FIFO
* R_DMA_CHx_HWSW bit 31-16=nbr of bytes left in DMA buffer (0=64k)
*/
- tty_lock_nested(); /* locked already when coming from close */
orig_jiffies = jiffies;
while (info->xmit.head != info->xmit.tail || /* More in send queue */
(*info->ostatusadr & 0x007f) || /* more in FIFO */
@@ -3952,7 +3951,6 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
curr_time_usec - info->last_tx_active_usec;
}
set_current_state(TASK_RUNNING);
- tty_unlock();
}
/*
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 851d7c2..cd85112 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -60,7 +60,7 @@ static struct lock_class_key port_lock_key;
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *old_termios);
-static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
+static void __uart_wait_until_sent(struct uart_port *port, int timeout);
static void uart_change_pm(struct uart_state *state, int pm_state);
/*
@@ -1322,8 +1322,16 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
tty->closing = 1;
spin_unlock_irqrestore(&port->lock, flags);
- if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
- tty_wait_until_sent(tty, msecs_to_jiffies(port->closing_wait));
+ if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE) {
+ /*
+ * hack: open-coded tty_wait_until_sent to avoid
+ * recursive tty_lock
+ */
+ long timeout = msecs_to_jiffies(port->closing_wait);
+ if (wait_event_interruptible_timeout(tty->write_wait,
+ !tty_chars_in_buffer(tty), timeout) >= 0)
+ __uart_wait_until_sent(uport, timeout);
+ }
/*
* At this point, we stop accepting input. To do this, we
@@ -1339,7 +1347,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
* has completely drained; this is especially
* important if there is a transmit FIFO!
*/
- uart_wait_until_sent(tty, uport->timeout);
+ __uart_wait_until_sent(uport, uport->timeout);
}
uart_shutdown(tty, state);
@@ -1373,17 +1381,13 @@ done:
mutex_unlock(&port->mutex);
}
-static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
+static void __uart_wait_until_sent(struct uart_port *port, int timeout)
{
- struct uart_state *state = tty->driver_data;
- struct uart_port *port = state->uart_port;
unsigned long char_time, expire;
if (port->type == PORT_UNKNOWN || port->fifosize == 0)
return;
- tty_lock_nested(); /* already locked when coming from close */
-
/*
* Set the check interval to be 1/5 of the estimated time to
* send a single character, and make it at least 1. The check
@@ -1429,6 +1433,15 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
break;
}
set_current_state(TASK_RUNNING); /* might not be needed */
+}
+
+static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
+{
+ struct uart_state *state = tty->driver_data;
+ struct uart_port *port = state->uart_port;
+
+ tty_lock();
+ __uart_wait_until_sent(port, timeout);
tty_unlock();
}
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