[PATCH AUTOSEL 5.17 28/60] serial: msm_serial: disable interrupts in __msm_console_write()

Sasha Levin
2022-06-07T19:12:24Z

From: John Ogness <john.ogness@linutronix.de>

[ Upstream commit aabdbb1b7a5819e18c403334a31fb0cc2c06ad41 ]

__msm_console_write() assumes that interrupts are disabled, but
with threaded console printers it is possible that the write()
callback of the console is called with interrupts enabled.

Explicitly disable interrupts using local_irq_save() to preserve
the assumed context.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20220506213324.470461-1-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/msm_serial.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 23c94b927776..e676ec761f18 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -1599,6 +1599,7 @@ static inline struct uart_port *msm_get_port_from_line(unsigned int line)
static void __msm_console_write(struct uart_port *port, const char *s,
unsigned int count, bool is_uartdm)
{
+ unsigned long flags;
int i;
int num_newlines = 0;
bool replaced = false;
@@ -1616,6 +1617,8 @@ static void __msm_console_write(struct uart_port *port, const char *s,
num_newlines++;
count += num_newlines;

+ local_irq_save(flags);
+
if (port->sysrq)
locked = 0;
else if (oops_in_progress)
@@ -1661,6 +1664,8 @@ static void __msm_console_write(struct uart_port *port, const char *s,

if (locked)
spin_unlock(&port->lock);
+
+ local_irq_restore(flags);
}

static void msm_console_write(struct console *co, const char *s,
--
2.35.1