Patch "serial: omap: fix runtime-pm handling on unbind" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    serial: omap: fix runtime-pm handling on unbind

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     serial-omap-fix-runtime-pm-handling-on-unbind.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 099bd73dc17ed77aa8c98323e043613b6e8f54fc Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Mon, 10 Apr 2017 11:21:38 +0200
Subject: serial: omap: fix runtime-pm handling on unbind

From: Johan Hovold <johan@kernel.org>

commit 099bd73dc17ed77aa8c98323e043613b6e8f54fc upstream.

An unbalanced and misplaced synchronous put was used to suspend the
device on driver unbind, something which with a likewise misplaced
pm_runtime_disable leads to external aborts when an open port is being
removed.

Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa024010
...
[<c046e760>] (serial_omap_set_mctrl) from [<c046a064>] (uart_update_mctrl+0x50/0x60)
[<c046a064>] (uart_update_mctrl) from [<c046a400>] (uart_shutdown+0xbc/0x138)
[<c046a400>] (uart_shutdown) from [<c046bd2c>] (uart_hangup+0x94/0x190)
[<c046bd2c>] (uart_hangup) from [<c045b760>] (__tty_hangup+0x404/0x41c)
[<c045b760>] (__tty_hangup) from [<c045b794>] (tty_vhangup+0x1c/0x20)
[<c045b794>] (tty_vhangup) from [<c046ccc8>] (uart_remove_one_port+0xec/0x260)
[<c046ccc8>] (uart_remove_one_port) from [<c046ef4c>] (serial_omap_remove+0x40/0x60)
[<c046ef4c>] (serial_omap_remove) from [<c04845e8>] (platform_drv_remove+0x34/0x4c)

Fix this up by resuming the device before deregistering the port and by
suspending and disabling runtime pm only after the port has been
removed.

Also make sure to disable autosuspend before disabling runtime pm so
that the usage count is balanced and device actually suspended before
returning.

Note that due to a negative autosuspend delay being set in probe, the
unbalanced put would actually suspend the device on first driver unbind,
while rebinding and again unbinding would result in a negative
power.usage_count.

Fixes: 7e9c8e7dbf3b ("serial: omap: make sure to suspend device before remove")
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/serial/omap-serial.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1725,9 +1725,13 @@ static int serial_omap_remove(struct pla
 {
 	struct uart_omap_port *up = platform_get_drvdata(dev);
 
+	pm_runtime_get_sync(up->dev);
+
+	uart_remove_one_port(&serial_omap_reg, &up->port);
+
+	pm_runtime_dont_use_autosuspend(up->dev);
 	pm_runtime_put_sync(up->dev);
 	pm_runtime_disable(up->dev);
-	uart_remove_one_port(&serial_omap_reg, &up->port);
 	pm_qos_remove_request(&up->pm_qos_request);
 	device_init_wakeup(&dev->dev, false);
 


Patches currently in stable-queue which might be from johan@kernel.org are

queue-4.9/usb-serial-ftdi_sio-add-device-id-for-microsemi-arrow-sf2plus-dev-kit.patch
queue-4.9/bluetooth-hci_bcm-add-missing-tty-device-sanity-check.patch
queue-4.9/bluetooth-hci_intel-add-missing-tty-device-sanity-check.patch
queue-4.9/serial-omap-fix-runtime-pm-handling-on-unbind.patch
queue-4.9/serial-omap-suspend-device-on-probe-errors.patch
queue-4.9/staging-gdm724x-gdm_mux-fix-use-after-free-on-module-unload.patch