openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

ARM: amba: Fix race condition with driver_override 

The driver_override implementation is susceptible to a race condition
when different threads are reading vs storing a different driver
override.  Add locking to avoid this race condition.

Cfr. commits 6265539776 ("driver core: platform: fix race
condition with driver_override") and 9561475db6 ("PCI: Fix race
condition with driver_override").

Fixes: 3cf3857134 ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven 2018-04-10 15:21:44 +02:00 committed by Greg Kroah-Hartman
parent 5f53624662
commit 6a7228d90d
1 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/amba/bus.c
View File

@ -69,8 +69,12 @@ static ssize_t driver_override_show(struct device *_dev,
struct device_attribute *attr, char *buf) struct device_attribute *attr, char *buf)
{ {
struct amba_device *dev = to_amba_device(_dev); struct amba_device *dev = to_amba_device(_dev);
ssize_t len;
return sprintf(buf, "%s\n", dev->driver_override); device_lock(_dev);
len = sprintf(buf, "%s\n", dev->driver_override);
device_unlock(_dev);
return len;
} }
static ssize_t driver_override_store(struct device *_dev, static ssize_t driver_override_store(struct device *_dev,
@ -78,7 +82,7 @@ static ssize_t driver_override_store(struct device *_dev,
const char *buf, size_t count) const char *buf, size_t count)
{ {
struct amba_device *dev = to_amba_device(_dev); struct amba_device *dev = to_amba_device(_dev);
char *driver_override, *old = dev->driver_override, *cp; char *driver_override, *old, *cp;
/* We need to keep extra room for a newline */ /* We need to keep extra room for a newline */
if (count >= (PAGE_SIZE - 1)) if (count >= (PAGE_SIZE - 1))
@ -92,12 +96,15 @@ static ssize_t driver_override_store(struct device *_dev,
if (cp) if (cp)
*cp = '\0'; *cp = '\0';
device_lock(_dev);
old = dev->driver_override;
if (strlen(driver_override)) { if (strlen(driver_override)) {
dev->driver_override = driver_override; dev->driver_override = driver_override;
} else { } else {
kfree(driver_override); kfree(driver_override);
dev->driver_override = NULL; dev->driver_override = NULL;
} }
device_unlock(_dev);
kfree(old); kfree(old);