From: Fushuai Wang <wangfushuai@baidu.com>
When two PnP devices map to the same physical port, the serial8250 driver
removes and re-registers the console structure for the same port.
During re-registration, the console structure still has CON_PRINTBUFFER set
from the initial registration, which causes console_init_seq() to set
console->seq to syslog_seq. This results in re-printing the entire
system log buffer, which may lead to RCU stall on slow serial consoles.
Clear CON_PRINTBUFFER when re-registering a port to prevent duplicate
log printing.
Fixes: 835d844d1a28 ("8250_pnp: do pnp probe before legacy probe")
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
---
V2->V3: Clear CON_PRINTBUFFER when remove the port
V1->V2: Add Fixes tag
drivers/tty/serial/8250/8250_core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index a428e88938eb..5419f1d22d47 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -716,8 +716,12 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
if (uart->port.type == PORT_8250_CIR)
return -ENODEV;
- if (uart->port.dev)
+ if (uart->port.dev) {
+ if (uart_console(&uart->port))
+ uart->port.cons->flags &= ~CON_PRINTBUFFER;
+
uart_remove_one_port(&serial8250_reg, &uart->port);
+ }
uart->port.ctrl_id = up->port.ctrl_id;
uart->port.port_id = up->port.port_id;
--
2.36.1