LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@armlinux.org.uk>,
	Adrian Salido <salidoa@google.com>,
	Nicolai Stange <nstange@suse.de>,
	Sasha Levin <Alexander.Levin@microsoft.com>,
	Todd Kjos <tkjos@android.com>,
	linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH v2 2/4] ARM: amba: Fix race condition with driver_override
Date: Tue, 10 Apr 2018 15:21:44 +0200	[thread overview]
Message-ID: <1523366506-19832-3-git-send-email-geert+renesas@glider.be> (raw)
In-Reply-To: <1523366506-19832-1-git-send-email-geert+renesas@glider.be>

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>
---
 drivers/amba/bus.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 6ffd778352e6d953..36c5653ced5742b7 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -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;
 
 	if (count > PATH_MAX)
 		return -EINVAL;
@@ -91,12 +95,15 @@ 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);
 
-- 
2.7.4

  parent reply	other threads:[~2018-04-10 13:21 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-10 13:21 [PATCH v2 0/4] ARM: amba: driver_override improvements and fixes Geert Uytterhoeven
2018-04-10 13:21 ` [PATCH v2 1/4] ARM: amba: Make driver_override output consistent with other buses Geert Uytterhoeven
2018-04-25 15:53   ` Todd Kjos
2018-04-10 13:21 ` Geert Uytterhoeven [this message]
2018-04-25 15:56   ` [PATCH v2 2/4] ARM: amba: Fix race condition with driver_override Todd Kjos
2018-04-25 16:06   ` Greg Kroah-Hartman
2018-04-25 17:53     ` Geert Uytterhoeven
2018-04-26  7:04       ` Greg Kroah-Hartman
2018-04-26  7:40         ` Geert Uytterhoeven
2018-04-26  8:35           ` Greg Kroah-Hartman
2018-04-26  8:45             ` Geert Uytterhoeven
2018-05-09 10:39               ` Russell King - ARM Linux
2018-05-09 13:32                 ` Geert Uytterhoeven
2018-05-09 14:50                   ` Greg Kroah-Hartman
2018-04-10 13:21 ` [PATCH v2 3/4] ARM: amba: Don't read past the end of sysfs "driver_override" buffer Geert Uytterhoeven
2018-04-25 15:56   ` Todd Kjos
2018-04-10 13:21 ` [PATCH v2 4/4] ARM: amba: Fix wrong indentation in driver_override_store() Geert Uytterhoeven
2018-04-25 15:58   ` Todd Kjos
2018-04-10 22:19 ` [PATCH v2 0/4] ARM: amba: driver_override improvements and fixes Russell King - ARM Linux
2018-04-25 16:08   ` Greg Kroah-Hartman
2018-04-25 17:27   ` Geert Uytterhoeven

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1523366506-19832-3-git-send-email-geert+renesas@glider.be \
    --to=geert+renesas@glider.be \
    --cc=Alexander.Levin@microsoft.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=nstange@suse.de \
    --cc=salidoa@google.com \
    --cc=tkjos@android.com \
    --subject='Re: [PATCH v2 2/4] ARM: amba: Fix race condition with driver_override' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).