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tty: serial: men_z135_uart.c: Fix race between IRQ and set_termios()

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commit 8117e34740 upstream.

Fix panic caused by a race between men_z135_intr() and men_z135_set_termios().

men_z135_intr() and men_z135_set_termios() both hold the struct uart_port::lock
spinlock, but men_z135_intr() does a spin_lock_irqsave() and
men_z135_set_termios() does a normal spin_lock(), which can lead to a deadlock
when an interrupt is called while the lock is being helt by
men_z135_set_termios().

This was discovered using a insmod, hardware looppback send/receive, rmmod
stress test.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Cc: Andreas Werner <andreas.werner@men.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johannes Thumshirn
2015-08-06 09:16:37 +02:00
committed by Greg Kroah-Hartman
parent bf14cc44d1
commit c7d416e290
1 changed files with 4 additions and 5 deletions
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9
drivers/tty/serial/men_z135_uart.c
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@@ -392,7 +392,6 @@ static irqreturn_t men_z135_intr(int irq, void *data)
struct men_z135_port *uart = (struct men_z135_port *)data; struct men_z135_port *uart = (struct men_z135_port *)data;
struct uart_port *port = &uart->port; struct uart_port *port = &uart->port;
bool handled = false; bool handled = false;
unsigned long flags;
int irq_id; int irq_id;
uart->stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG); uart->stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG);
@@ -401,7 +400,7 @@ static irqreturn_t men_z135_intr(int irq, void *data)
if (!irq_id) if (!irq_id)
goto out; goto out;
spin_lock_irqsave(&port->lock, flags); spin_lock(&port->lock);
/* It's save to write to IIR[7:6] RXC[9:8] */ /* It's save to write to IIR[7:6] RXC[9:8] */
iowrite8(irq_id, port->membase + MEN_Z135_STAT_REG); iowrite8(irq_id, port->membase + MEN_Z135_STAT_REG);
@@ -427,7 +426,7 @@ static irqreturn_t men_z135_intr(int irq, void *data)
handled = true; handled = true;
} }
spin_unlock_irqrestore(&port->lock, flags); spin_unlock(&port->lock);
out: out:
return IRQ_RETVAL(handled); return IRQ_RETVAL(handled);
} }
@@ -717,7 +716,7 @@ static void men_z135_set_termios(struct uart_port *port,
baud = uart_get_baud_rate(port, termios, old, 0, uart_freq / 16); baud = uart_get_baud_rate(port, termios, old, 0, uart_freq / 16);
spin_lock(&port->lock); spin_lock_irq(&port->lock);
if (tty_termios_baud_rate(termios)) if (tty_termios_baud_rate(termios))
tty_termios_encode_baud_rate(termios, baud, baud); tty_termios_encode_baud_rate(termios, baud, baud);
@@ -725,7 +724,7 @@ static void men_z135_set_termios(struct uart_port *port,
iowrite32(bd_reg, port->membase + MEN_Z135_BAUD_REG); iowrite32(bd_reg, port->membase + MEN_Z135_BAUD_REG);
uart_update_timeout(port, termios->c_cflag, baud); uart_update_timeout(port, termios->c_cflag, baud);
spin_unlock(&port->lock); spin_unlock_irq(&port->lock);
} }
static const char *men_z135_type(struct uart_port *port) static const char *men_z135_type(struct uart_port *port)