diff options
| author | John Ogness <john.ogness@linutronix.de> | 2023-05-25 11:37:59 +0206 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-30 11:45:42 +0100 |
| commit | d0b309a5d3f4648fd4fb1a255a7ae9fb98d87be3 (patch) | |
| tree | 89d0491d91746e06337ec8e8fc0a1172a7f95494 /drivers/tty/serial/8250/8250_omap.c | |
| parent | 25614735a647693c1260f253dc3ab32127697806 (diff) | |
serial: 8250: synchronize and annotate UART_IER access
The UART_IER register is modified twice by each console write
(serial8250_console_write()) under the port lock. Any driver code that
accesses UART_IER must do so with the port locked in order to ensure
consistent values, even when for read accesses.
Add locking, lockdep notation, and/or comments everywhere UART_IER is
accessed. The added locking is not fixing a real problem because it
occurs where the console is not active. However, adding the locking
to these non-critical paths greatly simplifies UART_IER access
tracking by establishing a general policy that all UART_IER access
is performed with the port locked.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230525093159.223817-9-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/8250/8250_omap.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_omap.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 3225c95fde1d..0498b9b0e4e9 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -533,6 +533,10 @@ static void omap_8250_pm(struct uart_port *port, unsigned int state, u8 efr; pm_runtime_get_sync(port->dev); + + /* Synchronize UART_IER access against the console. */ + spin_lock_irq(&port->lock); + serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); efr = serial_in(up, UART_EFR); serial_out(up, UART_EFR, efr | UART_EFR_ECB); @@ -543,6 +547,8 @@ static void omap_8250_pm(struct uart_port *port, unsigned int state, serial_out(up, UART_EFR, efr); serial_out(up, UART_LCR, 0); + spin_unlock_irq(&port->lock); + pm_runtime_mark_last_busy(port->dev); pm_runtime_put_autosuspend(port->dev); } @@ -760,8 +766,11 @@ static void omap_8250_shutdown(struct uart_port *port) if (priv->habit & UART_HAS_EFR2) serial_out(up, UART_OMAP_EFR2, 0x0); + /* Synchronize UART_IER access against the console. */ + spin_lock_irq(&port->lock); up->ier = 0; serial_out(up, UART_IER, 0); + spin_unlock_irq(&port->lock); disable_irq_nosync(up->port.irq); dev_pm_clear_wake_irq(port->dev); @@ -803,6 +812,7 @@ static void omap_8250_unthrottle(struct uart_port *port) pm_runtime_get_sync(port->dev); + /* Synchronize UART_IER access against the console. */ spin_lock_irqsave(&port->lock, flags); priv->throttled = false; if (up->dma) @@ -953,6 +963,7 @@ static void __dma_rx_complete(void *param) struct dma_tx_state state; unsigned long flags; + /* Synchronize UART_IER access against the console. */ spin_lock_irqsave(&p->port.lock, flags); /* @@ -1227,6 +1238,9 @@ static u16 omap_8250_handle_rx_dma(struct uart_8250_port *up, u8 iir, u16 status static void am654_8250_handle_rx_dma(struct uart_8250_port *up, u8 iir, u16 status) { + /* Port locked to synchronize UART_IER access against the console. */ + lockdep_assert_held_once(&up->port.lock); + /* * Queue a new transfer if FIFO has data. */ |