1. Patchew
  2. linux
  3. View series

[PATCH] tty: serial: fixed uart irq maybe cause irq storm

fengchunguo@126.com posted 1 patch 1 year, 10 months ago
There is a newer version of this series
drivers/tty/serial/8250/8250_dw.c | 9 +++++++++
1 file changed, 9 insertions(+)
[PATCH] tty: serial: fixed uart irq maybe cause irq storm
Posted by fengchunguo@126.com 1 year, 10 months ago 
From: "chunguo.feng" <chunguo.feng@semidrive.com>

if not disable uart irq before disable clk,  uart irq maybe triggered after
disabled clk immediately, then maybe cause irq storm.

Reproduced the below call trace, see i2c not be connected, but irq storm
was triggered.

i2c_designware 30b70000.i2c: controller timed out
CPU: 2 PID: 2932 Comm: gnss@1.0-servic 
Tainted: G O 5.14.61-00094-geaa0149416cc-dirty #8
Hardware name: Semidrive kunlun x9 REF Board (DT)
Call trace:
[<ffff00000808a3cc>] dump_backtrace+0x0/0x3c0
[<ffff00000808a7a0>] show_stack+0x14/0x1c
[<ffff000008cef43c>] dump_stack+0xc4/0xfc
[<ffff00000814eb80>] __report_bad_irq+0x50/0xe0
[<ffff00000814eaec>] note_interrupt+0x248/0x28c
[<ffff00000814c0e8>] handle_irq_event+0x78/0xa4
[<ffff00000814fcb8>] handle_fasteoi_irq+0xe4/0x1b4
[<ffff00000814b060>] __handle_domain_irq+0x7c/0xbc
[<ffff00000808176c>] gic_handle_irq+0x4c/0xb8
[<ffff000008083230>] el1_irq+0xb0/0x124
[<ffff000008d09f5c>] _raw_spin_unlock_irqrestore+0x10/0x44
[<ffff00000865b784>] dw8250_set_termios+0x48/0xf4
[<ffff0000086545a4>] serial8250_set_termios+0x14/0x28
[<ffff00000864c4f4>] uart_change_speed+0x38/0x10c
[<ffff00000864e458>] uart_set_termios+0xd0/0x17c
[<ffff000008630ad4>] tty_set_termios+0x160/0x1e4
[<ffff00000863165c>] set_termios+0x32c/0x3bc
[<ffff000008631248>] tty_mode_ioctl+0x6f0/0x7d8
[<ffff000008631a6c>] n_tty_ioctl_helper+0x10c/0x1e8
[<ffff00000862d2c4>] n_tty_ioctl+0x120/0x194
[<ffff00000862a724>] tty_ioctl+0x658/0xa34
[<ffff0000082a8f40>] do_vfs_ioctl+0x554/0x810
[<ffff0000082a9368>] SyS_ioctl+0x88/0x94
Exception stack(0xffff00000ccf3ec0 to 0xffff00000ccf4000

Signed-off-by: chunguo.feng <chunguo.feng@semidrive.com>
---
 drivers/tty/serial/8250/8250_dw.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index c1d43f0..133c24e 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -359,6 +359,12 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
 
 	rate = clk_round_rate(d->clk, newrate);
 	if (rate > 0 && p->uartclk != rate) {
+		/*Need disable uart irq before disabled clk, because uart irq maybe triggered after
+		 * disabled clk immediately, then cause irq storm.
+		 */
+		if (p->irq)
+			disabled_irq(p->irq);
+
 		clk_disable_unprepare(d->clk);
 		/*
 		 * Note that any clock-notifer worker will block in
@@ -368,6 +374,9 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
 		if (!ret)
 			p->uartclk = rate;
 		clk_prepare_enable(d->clk);
+
+		if (p->irq)
+			enable_irq(p->irq);
 	}
 
 	dw8250_do_set_termios(p, termios, old);
-- 
2.7.4
Re: [PATCH] tty: serial: fixed uart irq maybe cause irq storm
Posted by Greg KH 1 year, 10 months ago 
On Mon, Apr 01, 2024 at 05:30:01PM +0800, fengchunguo@126.com wrote:
> From: "chunguo.feng" <chunguo.feng@semidrive.com>

Please use your name, which is not with a "." in it, right?

> if not disable uart irq before disable clk,  uart irq maybe triggered after
> disabled clk immediately, then maybe cause irq storm.
> 
> Reproduced the below call trace, see i2c not be connected, but irq storm
> was triggered.
> 
> i2c_designware 30b70000.i2c: controller timed out
> CPU: 2 PID: 2932 Comm: gnss@1.0-servic 
> Tainted: G O 5.14.61-00094-geaa0149416cc-dirty #8
> Hardware name: Semidrive kunlun x9 REF Board (DT)
> Call trace:
> [<ffff00000808a3cc>] dump_backtrace+0x0/0x3c0
> [<ffff00000808a7a0>] show_stack+0x14/0x1c
> [<ffff000008cef43c>] dump_stack+0xc4/0xfc
> [<ffff00000814eb80>] __report_bad_irq+0x50/0xe0
> [<ffff00000814eaec>] note_interrupt+0x248/0x28c
> [<ffff00000814c0e8>] handle_irq_event+0x78/0xa4
> [<ffff00000814fcb8>] handle_fasteoi_irq+0xe4/0x1b4
> [<ffff00000814b060>] __handle_domain_irq+0x7c/0xbc
> [<ffff00000808176c>] gic_handle_irq+0x4c/0xb8
> [<ffff000008083230>] el1_irq+0xb0/0x124
> [<ffff000008d09f5c>] _raw_spin_unlock_irqrestore+0x10/0x44
> [<ffff00000865b784>] dw8250_set_termios+0x48/0xf4
> [<ffff0000086545a4>] serial8250_set_termios+0x14/0x28
> [<ffff00000864c4f4>] uart_change_speed+0x38/0x10c
> [<ffff00000864e458>] uart_set_termios+0xd0/0x17c
> [<ffff000008630ad4>] tty_set_termios+0x160/0x1e4
> [<ffff00000863165c>] set_termios+0x32c/0x3bc
> [<ffff000008631248>] tty_mode_ioctl+0x6f0/0x7d8
> [<ffff000008631a6c>] n_tty_ioctl_helper+0x10c/0x1e8
> [<ffff00000862d2c4>] n_tty_ioctl+0x120/0x194
> [<ffff00000862a724>] tty_ioctl+0x658/0xa34
> [<ffff0000082a8f40>] do_vfs_ioctl+0x554/0x810
> [<ffff0000082a9368>] SyS_ioctl+0x88/0x94
> Exception stack(0xffff00000ccf3ec0 to 0xffff00000ccf4000
> 
> Signed-off-by: chunguo.feng <chunguo.feng@semidrive.com>
> ---
>  drivers/tty/serial/8250/8250_dw.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index c1d43f0..133c24e 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -359,6 +359,12 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
>  
>  	rate = clk_round_rate(d->clk, newrate);
>  	if (rate > 0 && p->uartclk != rate) {
> +		/*Need disable uart irq before disabled clk, because uart irq maybe triggered after

Space needed after '*', right?

> +		 * disabled clk immediately, then cause irq storm.
> +		 */
> +		if (p->irq)
> +			disabled_irq(p->irq);

This feels wrong, the irq should not be turned off here, what happens if
some data comes in while this function is running?  Will it be lost?

thanks,

greg k-h

Patchew 2.1-devel-b67e4c2

© 2016 - 2026 Red Hat, Inc.