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authorGeert Uytterhoeven <geert+renesas@glider.be>2018-04-10 15:21:44 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-04-25 18:07:10 +0200
commit6b614a87f3f477571e319281e84dba11e0ea0a76 (patch)
treebb4455725169c7e4017c4bc6e27ccd981f1dc6d9 /drivers/amba
parent19972dd568f8d1e701f8051fcff56562e0551f63 (diff)
downloadblackbird-obmc-linux-6b614a87f3f477571e319281e84dba11e0ea0a76.tar.gz
blackbird-obmc-linux-6b614a87f3f477571e319281e84dba11e0ea0a76.zip
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 6265539776a0810b ("driver core: platform: fix race condition with driver_override") and 9561475db680f714 ("PCI: Fix race condition with driver_override"). Fixes: 3cf385713460eb2b ("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>
Diffstat (limited to 'drivers/amba')
-rw-r--r--drivers/amba/bus.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 594c228d2f02..c77eb6e65646 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -69,11 +69,15 @@ static ssize_t driver_override_show(struct device *_dev,
struct device_attribute *attr, char *buf)
{
struct amba_device *dev = to_amba_device(_dev);
+ ssize_t len;
if (!dev->driver_override)
return 0;
- 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,
@@ -81,7 +85,7 @@ static ssize_t driver_override_store(struct device *_dev,
const char *buf, size_t count)
{
struct amba_device *dev = to_amba_device(_dev);
- char *driver_override, *old = dev->driver_override, *cp;
+ char *driver_override, *old, *cp;
if (count > PATH_MAX)
return -EINVAL;
@@ -94,12 +98,15 @@ static ssize_t driver_override_store(struct device *_dev,
if (cp)
*cp = '\0';
+ device_lock(_dev);
+ old = dev->driver_override;
if (strlen(driver_override)) {
dev->driver_override = driver_override;
} else {
kfree(driver_override);
dev->driver_override = NULL;
}
+ device_unlock(_dev);
kfree(old);
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