patch "Revert "ARM: amba: Fix race condition with driver_override"" added to char-misc-linus

patch "Revert "ARM: amba: Fix race condition with driver_override"" added to char-misc-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    Revert "ARM: amba: Fix race condition with driver_override"

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 2891d4feae7c2cf0a56d84bf38519aae6c5060b5 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 26 Apr 2018 10:29:57 +0200
Subject: Revert "ARM: amba: Fix race condition with driver_override"

This reverts commit 6b614a87f3f477571e319281e84dba11e0ea0a76.

My backport was incorrect, as Geert pointed out :(

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/amba/bus.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 8e6ac3031662..fac8e36de11e 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -69,15 +69,11 @@ 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;
 
-	device_lock(_dev);
-	len = sprintf(buf, "%s\n", dev->driver_override);
-	device_unlock(_dev);
-	return len;
+	return sprintf(buf, "%s\n", dev->driver_override);
 }
 
 static ssize_t driver_override_store(struct device *_dev,
@@ -85,7 +81,7 @@ 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, *cp;
+	char *driver_override, *old = dev->driver_override, *cp;
 
 	/* We need to keep extra room for a newline */
 	if (count >= (PAGE_SIZE - 1))
@@ -99,15 +95,12 @@ 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);
 
-- 
2.17.0