linux-kernel - [PATCH] serial: sh-sci: Initialize spinlock for uart console

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Date:   Wed,  1 Jul 2020 16:41:40 +0100
From:   Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Cc:     linux-renesas-soc@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Prabhakar <prabhakar.csengg@...il.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH] serial: sh-sci: Initialize spinlock for uart console

serial core expects the spinlock to be initialized by the controller
driver for serial console, this patch makes sure the spinlock is
initialized, fixing the below issue:

[    0.865928] BUG: spinlock bad magic on CPU#0, swapper/0/1
[    0.865945]  lock: sci_ports+0x0/0x4c80, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
[    0.865955] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.8.0-rc1+ #112
[    0.865961] Hardware name: HopeRun HiHope RZ/G2H with sub board (DT)
[    0.865968] Call trace:
[    0.865979]  dump_backtrace+0x0/0x1d8
[    0.865985]  show_stack+0x14/0x20
[    0.865996]  dump_stack+0xe8/0x130
[    0.866006]  spin_dump+0x6c/0x88
[    0.866012]  do_raw_spin_lock+0xb0/0xf8
[    0.866023]  _raw_spin_lock_irqsave+0x80/0xa0
[    0.866032]  uart_add_one_port+0x3a4/0x4e0
[    0.866039]  sci_probe+0x504/0x7c8
[    0.866048]  platform_drv_probe+0x50/0xa0
[    0.866059]  really_probe+0xdc/0x330
[    0.866066]  driver_probe_device+0x58/0xb8
[    0.866072]  device_driver_attach+0x6c/0x90
[    0.866078]  __driver_attach+0x88/0xd0
[    0.866085]  bus_for_each_dev+0x74/0xc8
[    0.866091]  driver_attach+0x20/0x28
[    0.866098]  bus_add_driver+0x14c/0x1f8
[    0.866104]  driver_register+0x60/0x110
[    0.866109]  __platform_driver_register+0x40/0x48
[    0.866119]  sci_init+0x2c/0x34
[    0.866127]  do_one_initcall+0x88/0x428
[    0.866137]  kernel_init_freeable+0x2c0/0x328
[    0.866143]  kernel_init+0x10/0x108
[    0.866150]  ret_from_fork+0x10/0x18

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Reviewed-by: Biju Das <biju.das.jz@...renesas.com>
---
 drivers/tty/serial/sh-sci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index ae8463a..2d3169f 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -3298,6 +3298,9 @@ static int sci_probe_single(struct platform_device *dev,
 		sciport->port.flags |= UPF_HARD_FLOW;
 	}
 
+	if (sci_uart_driver.cons->index == sciport->port.line)
+		spin_lock_init(&sciport->port.lock);
+
 	ret = uart_add_one_port(&sci_uart_driver, &sciport->port);
 	if (ret) {
 		sci_cleanup_single(sciport);
-- 
2.7.4