This is a note to let you know that I've just added the patch titled
serial_core.c: add put_device() after device_find_child()
to the 3.9-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_core.c-add-put_device-after-device_find_child.patch
and it can be found in the queue-3.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5a65dcc04cda41f4122aacc37a5a348454645399 Mon Sep 17 00:00:00 2001
From: Federico Vaga <federico.vaga@xxxxxxxxx>
Date: Mon, 15 Apr 2013 16:01:07 +0200
Subject: serial_core.c: add put_device() after device_find_child()
From: Federico Vaga <federico.vaga@xxxxxxxxx>
commit 5a65dcc04cda41f4122aacc37a5a348454645399 upstream.
The serial core uses device_find_child() but does not drop the reference to
the retrieved child after using it. This patch add the missing put_device().
What I have done to test this issue.
I used a machine with an AMBA PL011 serial driver. I tested the patch on
next-20120408 because the last branch [next-20120415] does not boot on this
board.
For test purpose, I added some pr_info() messages to print the refcount
after device_find_child() (lines: 1937,2009), and after put_device()
(lines: 1947, 2021).
Boot the machine *without* put_device(). Then:
echo reboot > /sys/power/disk
echo disk > /sys/power/state
[ 87.058575] uart_suspend_port:1937 refcount 4
[ 87.058582] uart_suspend_port:1947 refcount 4
[ 87.098083] uart_resume_port:2009refcount 5
[ 87.098088] uart_resume_port:2021 refcount 5
echo disk > /sys/power/state
[ 103.055574] uart_suspend_port:1937 refcount 6
[ 103.055580] uart_suspend_port:1947 refcount 6
[ 103.095322] uart_resume_port:2009 refcount 7
[ 103.095327] uart_resume_port:2021 refcount 7
echo disk > /sys/power/state
[ 252.459580] uart_suspend_port:1937 refcount 8
[ 252.459586] uart_suspend_port:1947 refcount 8
[ 252.499611] uart_resume_port:2009 refcount 9
[ 252.499616] uart_resume_port:2021 refcount 9
The refcount continuously increased.
Boot the machine *with* this patch. Then:
echo reboot > /sys/power/disk
echo disk > /sys/power/state
[ 159.333559] uart_suspend_port:1937 refcount 4
[ 159.333566] uart_suspend_port:1947 refcount 3
[ 159.372751] uart_resume_port:2009 refcount 4
[ 159.372755] uart_resume_port:2021 refcount 3
echo disk > /sys/power/state
[ 185.713614] uart_suspend_port:1937 refcount 4
[ 185.713621] uart_suspend_port:1947 refcount 3
[ 185.752935] uart_resume_port:2009 refcount 4
[ 185.752940] uart_resume_port:2021 refcount 3
echo disk > /sys/power/state
[ 207.458584] uart_suspend_port:1937 refcount 4
[ 207.458591] uart_suspend_port:1947 refcount 3
[ 207.498598] uart_resume_port:2009 refcount 4
[ 207.498605] uart_resume_port:2021 refcount 3
The refcount correctly handled.
Signed-off-by: Federico Vaga <federico.vaga@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1941,6 +1941,8 @@ int uart_suspend_port(struct uart_driver
mutex_unlock(&port->mutex);
return 0;
}
+ put_device(tty_dev);
+
if (console_suspend_enabled || !uart_console(uport))
uport->suspended = 1;
@@ -2006,9 +2008,11 @@ int uart_resume_port(struct uart_driver
disable_irq_wake(uport->irq);
uport->irq_wake = 0;
}
+ put_device(tty_dev);
mutex_unlock(&port->mutex);
return 0;
}
+ put_device(tty_dev);
uport->suspended = 0;
/*
Patches currently in stable-queue which might be from federico.vaga@xxxxxxxxx are
queue-3.9/serial_core.c-add-put_device-after-device_find_child.patch
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