1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 1 Mar 2024 22:45:25 +0100
Subject: [PATCH 12/18] serial: sifive: Use uart_prepare_sysrq_char() to handle
sysrq.
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz
The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT.
The driver splits the locking function into two parts: local_irq_save() and
uart_port_lock() and this breaks PREEMPT_RT.
Handle sysrq requests sysrq once the port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: linux-riscv@lists.infradead.org
Link: https://lore.kernel.org/r/20240301215246.891055-13-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/tty/serial/sifive.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -412,7 +412,8 @@ static void __ssp_receive_chars(struct s
break;
ssp->port.icount.rx++;
- uart_insert_char(&ssp->port, 0, 0, ch, TTY_NORMAL);
+ if (!uart_prepare_sysrq_char(&ssp->port, ch))
+ uart_insert_char(&ssp->port, 0, 0, ch, TTY_NORMAL);
}
tty_flip_buffer_push(&ssp->port.state->port);
@@ -534,7 +535,7 @@ static irqreturn_t sifive_serial_irq(int
if (ip & SIFIVE_SERIAL_IP_TXWM_MASK)
__ssp_transmit_chars(ssp);
- uart_port_unlock(&ssp->port);
+ uart_unlock_and_check_sysrq(&ssp->port);
return IRQ_HANDLED;
}
@@ -791,13 +792,10 @@ static void sifive_serial_console_write(
if (!ssp)
return;
- local_irq_save(flags);
- if (ssp->port.sysrq)
- locked = 0;
- else if (oops_in_progress)
- locked = uart_port_trylock(&ssp->port);
+ if (oops_in_progress)
+ locked = uart_port_trylock_irqsave(&ssp->port, &flags);
else
- uart_port_lock(&ssp->port);
+ uart_port_lock_irqsave(&ssp->port, &flags);
ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
@@ -807,8 +805,7 @@ static void sifive_serial_console_write(
__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
if (locked)
- uart_port_unlock(&ssp->port);
- local_irq_restore(flags);
+ uart_port_unlock_irqrestore(&ssp->port, flags);
}
static int sifive_serial_console_setup(struct console *co, char *options)
|
