2017-08-20 22:02:02

by Alexandre Belloni

[permalink] [raw]

Subject: [PATCH] alarmtimer: ensure RTC module is not unloaded

---

When registering the rtc device to be used to handle alarm timers,
get_device is used to ensure the device doesn't go away but the module can
still be unloaded. Call try_module_get to ensure the rtc driver will not go
away.

Reported-by: Michal Simek <[email protected]>
Signed-off-by: Alexandre Belloni <[email protected]>
---
kernel/time/alarmtimer.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 0b8ff7d257ea..1c682eef7e6b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -28,6 +28,7 @@
#include <linux/workqueue.h>
#include <linux/freezer.h>
#include <linux/compat.h>
+#include <linux/module.h>

#include "posix-timers.h"

@@ -100,6 +101,11 @@ static int alarmtimer_rtc_add_device(struct device *dev,

spin_lock_irqsave(&rtcdev_lock, flags);
if (!rtcdev) {
+ if (!try_module_get(rtc->owner)) {
+ spin_unlock_irqrestore(&rtcdev_lock, flags);
+ return -1;
+ }
+
rtcdev = rtc;
/* hold a reference so it doesn't go away */
get_device(dev);
--
2.14.1

2017-08-21 09:42:41

by Michal Simek

[permalink] [raw]

Subject: Re: [PATCH] alarmtimer: ensure RTC module is not unloaded

---

On 21.8.2017 00:01, Alexandre Belloni wrote:
> When registering the rtc device to be used to handle alarm timers,
> get_device is used to ensure the device doesn't go away but the module can
> still be unloaded. Call try_module_get to ensure the rtc driver will not go
> away.
>
> Reported-by: Michal Simek <[email protected]>
> Signed-off-by: Alexandre Belloni <[email protected]>
> ---
> kernel/time/alarmtimer.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
> index 0b8ff7d257ea..1c682eef7e6b 100644
> --- a/kernel/time/alarmtimer.c
> +++ b/kernel/time/alarmtimer.c
> @@ -28,6 +28,7 @@
> #include <linux/workqueue.h>
> #include <linux/freezer.h>
> #include <linux/compat.h>
> +#include <linux/module.h>
>
> #include "posix-timers.h"
>
> @@ -100,6 +101,11 @@ static int alarmtimer_rtc_add_device(struct device *dev,
>
> spin_lock_irqsave(&rtcdev_lock, flags);
> if (!rtcdev) {
> + if (!try_module_get(rtc->owner)) {
> + spin_unlock_irqrestore(&rtcdev_lock, flags);
> + return -1;
> + }
> +
> rtcdev = rtc;
> /* hold a reference so it doesn't go away */
> get_device(dev);
>

Tested-by: Michal Simek <[email protected]>

Thanks,
Michal


--
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: http://www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Xilinx Microblaze
Maintainer of Linux kernel - Xilinx Zynq ARM and ZynqMP ARM64 SoCs
U-Boot custodian - Xilinx Microblaze/Zynq/ZynqMP SoCs

---

Attachments:

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2017-08-31 19:42:45

by tip-bot for Vasyl Gomonovych

[permalink] [raw]

Subject: [tip:timers/core] alarmtimer: Ensure RTC module is not unloaded

---

Commit-ID: 51218298a25e6942957c5595f2abf130d47d5df9
Gitweb: http://git.kernel.org/tip/51218298a25e6942957c5595f2abf130d47d5df9
Author: Alexandre Belloni <[email protected]>
AuthorDate: Mon, 21 Aug 2017 00:01:46 +0200
Committer: Thomas Gleixner <[email protected]>
CommitDate: Thu, 31 Aug 2017 21:36:45 +0200

alarmtimer: Ensure RTC module is not unloaded

When registering the rtc device to be used to handle alarm timers,
get_device is used to ensure the device doesn't go away but the module can
still be unloaded.

Call try_module_get to ensure the rtc driver will not go away.

Reported-and-tested-by: Michal Simek <[email protected]>
Signed-off-by: Alexandre Belloni <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: John Stultz <[email protected]>
Cc: Stephen Boyd <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]

---
kernel/time/alarmtimer.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 73a2b47..ec09ce9 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -28,6 +28,7 @@
#include <linux/workqueue.h>
#include <linux/freezer.h>
#include <linux/compat.h>
+#include <linux/module.h>

#include "posix-timers.h"

@@ -103,6 +104,11 @@ static int alarmtimer_rtc_add_device(struct device *dev,

spin_lock_irqsave(&rtcdev_lock, flags);
if (!rtcdev) {
+ if (!try_module_get(rtc->owner)) {
+ spin_unlock_irqrestore(&rtcdev_lock, flags);
+ return -1;
+ }
+
rtcdev = rtc;
/* hold a reference so it doesn't go away */
get_device(dev);