At boot time, probe function of multiple connected devices (proprietary devices) execute simultaneously. And because of the following code path race condition happens: probe->usb_register_dev->init_usb_class Tested with these changes, and problem has been solved. thanks, ajay kaher --------- Original Message --------- Sender : gregkh@xxxxxxxxxxxxxxxxxxx <gregkh@xxxxxxxxxxxxxxxxxxx> Date : 2017-01-30 14:36 (GMT+5:30) Title : Re: Subject: [PATCH v1] USB:Core: BugFix: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously On Mon, Jan 30, 2017 at 08:25:25AM +0000, Ajay Kaher wrote: > First off, you are sending html email, which the mailing list keeps rejecting, why are you ignoring that? > > There is race condition when two USB class drivers try to call > > init_usb_class at the same time and leads to crash. > > > > The main reason for this is one of the Class drivers allocates memory > for usb_class structure and initializes its member. In the meantime NULL > check for usb_class structure fails and assumes that usb_class structure > is properly initialized and crashed while trying to access its members. > > > > To avoid this race condition locking required before calling > init_usb_class from function usb_register_dev. > > > > > > Signed-off-by: Ajay Kaher Does this look correct? Please work with some of the samsung kernel developers for how to properly submit a patch. And finally, how are two drivers calling init_usb_class() at the same time? What code path causes that? Have you seen this happen, and if so, what drivers caused it? thanks, greg k-h
