This is a note to let you know that I've just added the patch titled
serial: mxs-auart: add spinlock around changing cts state
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-mxs-auart-add-spinlock-around-changing-cts-st.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a415cab513a700c984ba88682b1541856db3dcb6
Author: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx>
Date: Wed Mar 20 12:15:36 2024 +0000
serial: mxs-auart: add spinlock around changing cts state
[ Upstream commit 54c4ec5f8c471b7c1137a1f769648549c423c026 ]
The uart_handle_cts_change() function in serial_core expects the caller
to hold uport->lock. For example, I have seen the below kernel splat,
when the Bluetooth driver is loaded on an i.MX28 board.
[ 85.119255] ------------[ cut here ]------------
[ 85.124413] WARNING: CPU: 0 PID: 27 at /drivers/tty/serial/serial_core.c:3453 uart_handle_cts_change+0xb4/0xec
[ 85.134694] Modules linked in: hci_uart bluetooth ecdh_generic ecc wlcore_sdio configfs
[ 85.143314] CPU: 0 PID: 27 Comm: kworker/u3:0 Not tainted 6.6.3-00021-gd62a2f068f92 #1
[ 85.151396] Hardware name: Freescale MXS (Device Tree)
[ 85.156679] Workqueue: hci0 hci_power_on [bluetooth]
(...)
[ 85.191765] uart_handle_cts_change from mxs_auart_irq_handle+0x380/0x3f4
[ 85.198787] mxs_auart_irq_handle from __handle_irq_event_percpu+0x88/0x210
(...)
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 4d90bb147ef6 ("serial: core: Document and assert lock requirements for irq helpers")
Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
Signed-off-by: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240320121530.11348-1-emil.kronborg@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 5d483e996514f..a8eb98e37af48 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1126,11 +1126,13 @@ static void mxs_auart_set_ldisc(struct uart_port *port,
static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
{
- u32 istat;
+ u32 istat, stat;
struct mxs_auart_port *s = context;
u32 mctrl_temp = s->mctrl_prev;
- u32 stat = mxs_read(s, REG_STAT);
+ uart_port_lock(&s->port);
+
+ stat = mxs_read(s, REG_STAT);
istat = mxs_read(s, REG_INTR);
/* ack irq */
@@ -1166,6 +1168,8 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
istat &= ~AUART_INTR_TXIS;
}
+ uart_port_unlock(&s->port);
+
return IRQ_HANDLED;
}
