From: Andy Shevchenko andriy.shevchenko@linux.intel.com

stable inclusion from stable-v4.19.316 commit 44b38924135d2093e2ec1812969464845dd66dc9 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA7D3L

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 77ab53371a2066fdf9b895246505f5ef5a4b5d47 ]

uart_handle_cts_change() has to be called with port lock taken, Since we run it in a separate work, the lock may not be taken at the time of running. Make sure that it's taken by explicitly doing that. Without it we got a splat:

WARNING: CPU: 0 PID: 10 at drivers/tty/serial/serial_core.c:3491 uart_handle_cts_change+0xa6/0xb0 ... Workqueue: max3100-0 max3100_work [max3100] RIP: 0010:uart_handle_cts_change+0xa6/0xb0 ... max3100_handlerx+0xc5/0x110 [max3100] max3100_work+0x12a/0x340 [max3100]

Fixes: 7831d56b0a35 ("tty: MAX3100") Signed-off-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Link: https://lore.kernel.org/r/20240402195306.269276-2-andriy.shevchenko@linux.in... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yi Yang yiyang13@huawei.com --- drivers/tty/serial/max3100.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c index 371569a0fd00..915d7753eec2 100644 --- a/drivers/tty/serial/max3100.c +++ b/drivers/tty/serial/max3100.c @@ -213,7 +213,7 @@ static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx) return 0; }

-static int max3100_handlerx(struct max3100_port *s, u16 rx) +static int max3100_handlerx_unlocked(struct max3100_port *s, u16 rx) { unsigned int ch, flg, status = 0; int ret = 0, cts; @@ -253,6 +253,17 @@ static int max3100_handlerx(struct max3100_port *s, u16 rx) return ret; }

+static int max3100_handlerx(struct max3100_port *s, u16 rx) +{ + unsigned long flags; + int ret; + + uart_port_lock_irqsave(&s->port, &flags); + ret = max3100_handlerx_unlocked(s, rx); + uart_port_unlock_irqrestore(&s->port, flags); + return ret; +} + static void max3100_work(struct work_struct *w) { struct max3100_port *s = container_of(w, struct max3100_port, work);