diff options
| author |   Thomas Abraham <thomas.abraham@linaro.org> | 2012-11-22 18:06:28 +0530 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-11-26 15:36:39 -0800 |
| commit | c15c3747ee32b6969f3cfbc86dc94923e3742d0a (patch) | |
| tree | 2c2f9b77abcaa8f116e6f87bf91208e6013d3fee /drivers/tty | |
| parent | tty: vt: Remove redundant null check before kfree. (diff) | |
| download | linux-dev-c15c3747ee32b6969f3cfbc86dc94923e3742d0a.tar.xz linux-dev-c15c3747ee32b6969f3cfbc86dc94923e3742d0a.zip | |
serial: samsung: fix potential soft lockup during uart write
Certain tty line discipline implementations such slip and bluetooth hci invoke
the serial core uart_write() api in their write_wakeup callback. This leads to
a soft lockup with samsung serial driver since the uart port lock is taken in
the driver's interrupt handler and uart_write() attempts to take the same lock
again.
Fix this issue by releasing the uart port lock before the call to
uart_write_wakeup() in the tx handler. Also move the spin-lock/unlock sequence
from s3c64xx_serial_handle_irq() function into the tx and rx irq handlers so
that this change is applicable to s3c24xx platforms as well.
Reported-by: Kyungmin Park <kyungmin.park@samsung.com>
Reported-by: Hyeonkook Kim <hk619.kim@samsung.com>
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/samsung.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c index 82b48f60aa0c..9368c3e81cc8 100644 --- a/drivers/tty/serial/samsung.c +++ b/drivers/tty/serial/samsung.c @@ -223,8 +223,11 @@ s3c24xx_serial_rx_chars(int irq, void *dev_id) struct uart_port *port = &ourport->port; struct tty_struct *tty = port->state->port.tty; unsigned int ufcon, ch, flag, ufstat, uerstat; + unsigned long flags; int max_count = 64; + spin_lock_irqsave(&port->lock, flags); + while (max_count-- > 0) { ufcon = rd_regl(port, S3C2410_UFCON); ufstat = rd_regl(port, S3C2410_UFSTAT); @@ -299,6 +302,7 @@ s3c24xx_serial_rx_chars(int irq, void *dev_id) tty_flip_buffer_push(tty); out: + spin_unlock_irqrestore(&port->lock, flags); return IRQ_HANDLED; } @@ -307,8 +311,11 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id) struct s3c24xx_uart_port *ourport = id; struct uart_port *port = &ourport->port; struct circ_buf *xmit = &port->state->xmit; + unsigned long flags; int count = 256; + spin_lock_irqsave(&port->lock, flags); + if (port->x_char) { wr_regb(port, S3C2410_UTXH, port->x_char); port->icount.tx++; @@ -336,13 +343,17 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id) port->icount.tx++; } - if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) { + spin_unlock(&port->lock); uart_write_wakeup(port); + spin_lock(&port->lock); + } if (uart_circ_empty(xmit)) s3c24xx_serial_stop_tx(port); out: + spin_unlock_irqrestore(&port->lock, flags); return IRQ_HANDLED; } @@ -352,10 +363,8 @@ static irqreturn_t s3c64xx_serial_handle_irq(int irq, void *id) struct s3c24xx_uart_port *ourport = id; struct uart_port *port = &ourport->port; unsigned int pend = rd_regl(port, S3C64XX_UINTP); - unsigned long flags; irqreturn_t ret = IRQ_HANDLED; - spin_lock_irqsave(&port->lock, flags); if (pend & S3C64XX_UINTM_RXD_MSK) { ret = s3c24xx_serial_rx_chars(irq, id); wr_regl(port, S3C64XX_UINTP, S3C64XX_UINTM_RXD_MSK); @@ -364,7 +373,6 @@ static irqreturn_t s3c64xx_serial_handle_irq(int irq, void *id) ret = s3c24xx_serial_tx_chars(irq, id); wr_regl(port, S3C64XX_UINTP, S3C64XX_UINTM_TXD_MSK); } - spin_unlock_irqrestore(&port->lock, flags); return ret; } |