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Commit 6a7228d9 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Greg Kroah-Hartman
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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 62655397 ("driver core: platform: fix race
condition with driver_override") and 9561475d ("PCI: Fix race
condition with driver_override").

Fixes: 3cf38571 ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: default avatarTodd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5f536246

drivers/amba/bus.c

+9 −2
Original line number Diff line number Diff line
@@ -69,8 +69,12 @@ 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;



	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,
@@ -78,7 +82,7 @@ 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;



	/* We need to keep extra room for a newline */

	if (count >= (PAGE_SIZE - 1))
@@ -92,12 +96,15 @@ 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);