patch "serial: sh-sci: Initialize spinlock for uart console" added to tty-linus

-----Original Message-----
From: [email protected] <[email protected]>
Sent: 03 July 2020 09:41
To: Prabhakar Mahadev Lad <[email protected]>; Biju Das <[email protected]>; [email protected]; [email protected]
Subject: patch "serial: sh-sci: Initialize spinlock for uart console" added to tty-linus

This is a note to let you know that I've just added the patch titled

serial: sh-sci: Initialize spinlock for uart console

to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From f38278e9b810b06aff2981d505267be984423ba3 Mon Sep 17 00:00:00 2001
From: Lad Prabhakar <[email protected]>
Date: Wed, 1 Jul 2020 16:41:40 +0100
Subject: 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 <[email protected]>

Reviewed-by Biju Das <[email protected]>

Fixes a3cb39d258ef ("serial: core: Allow detach and attach serial device for console")

Cc stable <[email protected]>

Link https://lore.kernel.org/r/1593618100-2151-1-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com open here

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 drivers/tty/serial/sh-sci.c | 3 +++
 1 file changed, 3 insertions(+)

drivers/tty/serial/sh-sci.c +3 -1

index e1179e74a2b8..204bb68ce3ca 100644
@@ -3301,6 +3301,9 @@ 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);
--

2.27.0

Hi Greg,

Quoted 22 lines

-----Original Message-----
From: [email protected] <[email protected]>
Sent: 03 July 2020 09:41
To: Prabhakar Mahadev Lad <[email protected]>; Biju Das <[email protected]>; [email protected]; [email protected]
Subject: patch "serial: sh-sci: Initialize spinlock for uart console" added to tty-linus

This is a note to let you know that I've just added the patch titled

serial: sh-sci: Initialize spinlock for uart console

to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

Quoted 2 lines

If you have any questions about this process, please let me know.

It looks like it's a regression in serial_core.c [1] as Geert pointed out [2]. Please drop this patch until we come to a conclusion.

[1] https://www.spinics.net/lists/linux-serial/msg37119.html
[2] https://patchwork.kernel.org/patch/11636731/

Quoted 26 lines · Prabhakar Mahadev Lad

Quoted 16 lines

-----Original Message-----
From: [email protected] <[email protected]>
Sent: 03 July 2020 09:41
To: Prabhakar Mahadev Lad <[email protected]>; Biju Das <[email protected]>; [email protected]; [email protected]
Subject: patch "serial: sh-sci: Initialize spinlock for uart console" added to tty-linus

This is a note to let you know that I've just added the patch titled

serial: sh-sci: Initialize spinlock for uart console

to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

Quoted 8 lines

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

It looks like it's a regression in serial_core.c [1] as Geert pointed out [2]. Please drop this patch until we come to a conclusion.

Quoted 2 lines

[1] https://www.spinics.net/lists/linux-serial/msg37119.html
[2] https://patchwork.kernel.org/patch/11636731/

We have had MANY patches for individual drivers to fix up the issue with that serial_core patch. I think, and hope, they are all now caught. If not, please let us know, but for now, this patch is needed, so I'll keep it.