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| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2018-04-10 15:21:44 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-26 10:35:04 +0200 |
| commit | 6a7228d90d42bcacfe38786756ba62762b91c20a (patch) | |
| tree | 16f072e45e22a3ccbc94ae82b9deafa9e28e0ea7 /drivers/amba | |
| parent | 5f53624662eaac89598641cee6cd54fc192572d9 (diff) | |
| download | lwn-6a7228d90d42bcacfe38786756ba62762b91c20a.tar.gz lwn-6a7228d90d42bcacfe38786756ba62762b91c20a.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.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index f8c01fbef64d..4a3ac31c07d0 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; /* 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); |