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Subject[PATCH 17/36] sysdev: detect multiple driver registrations
Date
From: Ben Dooks <ben@fluff.org>

I've just found how easy it is to accidentally register a sysdev_driver for
two different classes. When this happens, bad things happen as the
sysdev_driver structure keeps has the list entry for the driver
registration.

The following patch makes a WARN_ON() if this happens, although I think
BUG_ON or returning -EAGAIN could also be valid responses to this.

Signed-off-by: Ben Dooks <ben@fluff.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/base/sys.c | 16 ++++++++++++++++
1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/drivers/base/sys.c b/drivers/base/sys.c
index 8e13fd9..1a06c23 100644
--- a/drivers/base/sys.c
+++ b/drivers/base/sys.c
@@ -167,6 +167,22 @@ int sysdev_driver_register(struct sysdev_class *cls, struct sysdev_driver *drv)
{
int err = 0;

+ if (!cls) {
+ printk(KERN_WARNING "sysdev: invalid class passed to "
+ "sysdev_driver_register!\n");
+ WARN_ON(1);
+ return -EINVAL;
+ }
+
+ /* Check whether this driver has already been added to a class. */
+ if ((drv->entry.next != drv->entry.prev) ||
+ (drv->entry.next != NULL)) {
+ printk(KERN_WARNING "sysdev: class %s: driver (%p) has already"
+ " been registered to a class, something is wrong, but "
+ "will forge on!\n", cls->name, drv);
+ WARN_ON(1);
+ }
+
mutex_lock(&sysdev_drivers_lock);
if (cls && kset_get(&cls->kset)) {
list_add_tail(&drv->entry, &cls->drivers);
--
1.5.4.5


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