| Message ID | 20250405145354.492947-1-ryotkkr98@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] serial: sifive: lock port in startup()/shutdown() callbacks | expand |
On Sat 2025-04-05 23:53:54, Ryo Takakura wrote: > startup()/shutdown() callbacks access SIFIVE_SERIAL_IE_OFFS. > The register is also accessed from write() callback. > > If console were printing and startup()/shutdown() callback > gets called, its access to the register could be overwritten. > > Add port->lock to startup()/shutdown() callbacks to make sure > their access to SIFIVE_SERIAL_IE_OFFS is synchronized against > write() callback. > > Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART") > Signed-off-by: Ryo Takakura <ryotkkr98@gmail.com> > Cc: stable@vger.kernel.org I do not have the hardware around so I could not test it. But the change make sense. It fixes a real race. And the code looks reasonable: Reviewed-by: Petr Mladek <pmladek@suse.com> Best Regards, Petr
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c index 5904a2d4c..054a8e630 100644 --- a/drivers/tty/serial/sifive.c +++ b/drivers/tty/serial/sifive.c @@ -563,8 +563,11 @@ static void sifive_serial_break_ctl(struct uart_port *port, int break_state) static int sifive_serial_startup(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); + unsigned long flags; + uart_port_lock_irqsave(&ssp->port, &flags); __ssp_enable_rxwm(ssp); + uart_port_unlock_irqrestore(&ssp->port, flags); return 0; } @@ -572,9 +575,12 @@ static int sifive_serial_startup(struct uart_port *port) static void sifive_serial_shutdown(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); + unsigned long flags; + uart_port_lock_irqsave(&ssp->port, &flags); __ssp_disable_rxwm(ssp); __ssp_disable_txwm(ssp); + uart_port_unlock_irqrestore(&ssp->port, flags); } /**
startup()/shutdown() callbacks access SIFIVE_SERIAL_IE_OFFS. The register is also accessed from write() callback. If console were printing and startup()/shutdown() callback gets called, its access to the register could be overwritten. Add port->lock to startup()/shutdown() callbacks to make sure their access to SIFIVE_SERIAL_IE_OFFS is synchronized against write() callback. Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART") Signed-off-by: Ryo Takakura <ryotkkr98@gmail.com> Cc: stable@vger.kernel.org --- This patch used be part of a series for converting sifive driver to nbcon[0]. It's now sent seperatly as the rest of the series does not need be applied to the stable branch. Sincerely, Ryo Takakura [0] https://lore.kernel.org/all/20250405043833.397020-1-ryotkkr98@gmail.com/ --- drivers/tty/serial/sifive.c | 6 ++++++ 1 file changed, 6 insertions(+)