When executing 'echo mem > /sys/power/state', the following
deadlock occurs. Since there is output during the serial
port entering the suspend process, the suspend will be
interrupted, resulting in the nesting of locks. Therefore,
use uart_port_lock_irq() instead of uart_port_unlock().
WARNING: inconsistent lock state
6.12.0-rc2-00002-g3c199ed5bd64-dirty #23 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
sh/494 [HC0[0]:SC0[0]:HE1:SE1] takes:
c4db5850 (&port_lock_key){?.-.}-{3:3}, at: imx_uart_enable_wakeup+0x14/0x254
{IN-HARDIRQ-W} state was registered at:
lock_acquire+0x104/0x348
_raw_spin_lock+0x48/0x84
imx_uart_int+0x14/0x4dc
__handle_irq_event_percpu+0xac/0x2fc
handle_irq_event_percpu+0xc/0x40
handle_irq_event+0x38/0x8c
handle_fasteoi_irq+0xb4/0x1b8
handle_irq_desc+0x1c/0x2c
gic_handle_irq+0x6c/0xa0
generic_handle_arch_irq+0x2c/0x64
call_with_stack+0x18/0x20
__irq_svc+0x9c/0xbc
_raw_spin_unlock_irqrestore+0x2c/0x48
uart_write+0xd8/0x3a0
do_output_char+0x1a8/0x1e4
n_tty_write+0x224/0x440
file_tty_write.constprop.0+0x124/0x250
do_iter_readv_writev+0x100/0x1e0
vfs_writev+0xc4/0x448
do_writev+0x68/0xf8
ret_fast_syscall+0x0/0x1c
irq event stamp: 31593
hardirqs last enabled at (31593): [<c1150e48>] _raw_spin_unlock_irqrestore+0x44/0x48
hardirqs last disabled at (31592): [<c07f32f0>] clk_enable_lock+0x60/0x120
softirqs last enabled at (30334): [<c012d1d4>] handle_softirqs+0x2cc/0x478
softirqs last disabled at (30325): [<c012d510>] __irq_exit_rcu+0x120/0x15c
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&port_lock_key);
<Interrupt>
lock(&port_lock_key);
Fixes: 3c199ed5bd64 ("serial: imx: Grab port lock in imx_uart_enable_wakeup()")
Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Reviewed-by: Fabio Estevam <festevam@xxxxxxxxx>
---
v1:
https://patchwork.kernel.org/project/linux-arm-kernel/patch/20241209124732.693834-1-xiaolei.wang@xxxxxxxxxxxxx/
v2:
use uart_port_lock_irq() instead of uart_port_lock_irqsave()
v3:
update commit log 'ehco --> echo'
drivers/tty/serial/imx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 17f70e4bee43..9c59ec128bb4 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2692,7 +2692,7 @@ static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
{
u32 ucr3;
- uart_port_lock(&sport->port);
+ uart_port_lock_irq(&sport->port);
ucr3 = imx_uart_readl(sport, UCR3);
if (on) {
@@ -2714,7 +2714,7 @@ static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
imx_uart_writel(sport, ucr1, UCR1);
}
- uart_port_unlock(&sport->port);
+ uart_port_unlock_irq(&sport->port);
}
static int imx_uart_suspend_noirq(struct device *dev)
--
2.25.1
