diff options
| author | John Ogness <john.ogness@linutronix.de> | 2023-05-25 12:31:59 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-30 13:45:42 +0300 |
| commit | d0b309a5d3f4648fd4fb1a255a7ae9fb98d87be3 (patch) | |
| tree | 89d0491d91746e06337ec8e8fc0a1172a7f95494 /drivers/tty/serial/8250/8250.h | |
| parent | 25614735a647693c1260f253dc3ab32127697806 (diff) | |
| download | linux-d0b309a5d3f4648fd4fb1a255a7ae9fb98d87be3.tar.xz | |
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.h')
| -rw-r--r-- | drivers/tty/serial/8250/8250.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 5418708f4631..471c6bc5f78f 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -179,6 +179,9 @@ static inline void serial_dl_write(struct uart_8250_port *up, u32 value) static inline bool serial8250_set_THRI(struct uart_8250_port *up) { + /* Port locked to synchronize UART_IER access against the console. */ + lockdep_assert_held_once(&up->port.lock); + if (up->ier & UART_IER_THRI) return false; up->ier |= UART_IER_THRI; @@ -188,6 +191,9 @@ static inline bool serial8250_set_THRI(struct uart_8250_port *up) static inline bool serial8250_clear_THRI(struct uart_8250_port *up) { + /* Port locked to synchronize UART_IER access against the console. */ + lockdep_assert_held_once(&up->port.lock); + if (!(up->ier & UART_IER_THRI)) return false; up->ier &= ~UART_IER_THRI; |