From: "Maciej W. Rozycki" The ->start_tx(), ->stop_tx() and ->stop_rx() backends are called with the port's lock already taken. Remove locking from within them and wrap around calls as necessary. Signed-off-by: Maciej W. Rozycki Cc: Jiri Slaby Signed-off-by: Andrew Morton --- drivers/serial/dz.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff -puN drivers/serial/dz.c~dz-fix-locking-issues drivers/serial/dz.c --- a/drivers/serial/dz.c~dz-fix-locking-issues +++ a/drivers/serial/dz.c @@ -108,37 +108,28 @@ static void dz_stop_tx(struct uart_port { struct dz_port *dport = (struct dz_port *)uport; unsigned short tmp, mask = 1 << dport->port.line; - unsigned long flags; - spin_lock_irqsave(&dport->port.lock, flags); tmp = dz_in(dport, DZ_TCR); /* read the TX flag */ tmp &= ~mask; /* clear the TX flag */ dz_out(dport, DZ_TCR, tmp); - spin_unlock_irqrestore(&dport->port.lock, flags); } static void dz_start_tx(struct uart_port *uport) { struct dz_port *dport = (struct dz_port *)uport; unsigned short tmp, mask = 1 << dport->port.line; - unsigned long flags; - spin_lock_irqsave(&dport->port.lock, flags); tmp = dz_in(dport, DZ_TCR); /* read the TX flag */ tmp |= mask; /* set the TX flag */ dz_out(dport, DZ_TCR, tmp); - spin_unlock_irqrestore(&dport->port.lock, flags); } static void dz_stop_rx(struct uart_port *uport) { struct dz_port *dport = (struct dz_port *)uport; - unsigned long flags; - spin_lock_irqsave(&dport->port.lock, flags); dport->cflag &= ~DZ_CREAD; dz_out(dport, DZ_LPR, dport->cflag | dport->port.line); - spin_unlock_irqrestore(&dport->port.lock, flags); } static void dz_enable_ms(struct uart_port *port) @@ -268,7 +259,9 @@ static inline void dz_transmit_chars(str } /* If nothing to do or stopped or hardware stopped. */ if (uart_circ_empty(xmit) || uart_tx_stopped(&dport->port)) { + spin_lock(&dport->port.lock); dz_stop_tx(&dport->port); + spin_unlock(&dport->port.lock); return; } @@ -285,8 +278,11 @@ static inline void dz_transmit_chars(str uart_write_wakeup(&dport->port); /* Are we are done. */ - if (uart_circ_empty(xmit)) + if (uart_circ_empty(xmit)) { + spin_lock(&dport->port.lock); dz_stop_tx(&dport->port); + spin_unlock(&dport->port.lock); + } } /* @@ -417,7 +413,12 @@ static int dz_startup(struct uart_port * */ static void dz_shutdown(struct uart_port *uport) { - dz_stop_tx(uport); + struct dz_port *dport = (struct dz_port *)uport; + unsigned long flags; + + spin_lock_irqsave(&dport->port.lock, flags); + dz_stop_tx(&dport->port); + spin_unlock_irqrestore(&dport->port.lock, flags); } /* _