From: Emil Kronborg <emil.kronborg@protonmail.com>
To: jirislaby@kernel.org, gregkh@linuxfoundation.org
Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev,
Emil Kronborg <emil.kronborg@protonmail.com>,
stable@vger.kernel.org
Subject: [PATCH v2] serial: mxs-auart: add spinlock around changing cts state
Date: Tue, 19 Mar 2024 18:02:47 +0000 [thread overview]
Message-ID: <20240319180239.69765-1-emil.kronborg@protonmail.com> (raw)
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@vger.kernel.org # v6.1+
Fixes: 4d90bb147ef6 ("serial: core: Document and assert lock requirements for irq helpers")
Signed-off-by: Emil Kronborg <emil.kronborg@protonmail.com>
---
Changes in v2:
- Add more of the stack trace to show why the lock is necessary. Note
that i removed some unrelated noise for unwinding, showing and dumping
the stack trace.
- Add Fixes tag. Note that this commit do not fix 4d90bb147ef6 ("serial:
core: Document and assert lock requirements for irq helpers") as such,
but it was the closest commit I could find that makes sense.
- Cc stable. Commit b0af4bcb4946 ("serial: core: Provide port lock
wrappers") is a prerequisite. Therefore, v6.1+.
drivers/tty/serial/mxs-auart.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 4749331fe618..1e8853eae504 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1086,11 +1086,13 @@ 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 */
@@ -1126,6 +1128,8 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
istat &= ~AUART_INTR_TXIS;
}
+ uart_port_unlock(&s->port);
+
return IRQ_HANDLED;
}
--
2.44.0
next reply other threads:[~2024-03-19 18:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-19 18:02 Emil Kronborg [this message]
2024-03-19 18:22 ` [PATCH v2] serial: mxs-auart: add spinlock around changing cts state Frank Li
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