> -----Original Message----- > From: Greg KH [mailto:greg@xxxxxxxxx] > Sent: Wednesday, April 26, 2006 10:41 PM > To: Vishal Sharda > Cc: tyler@xxxxxxxx; kernelnewbies@xxxxxxxxxxxx > Subject: Re: function "class_device_add" in inux26/drivers/base/class.c > > > A: Because it messes up the order in which people normally read text. > Q: Why is top-posting such a bad thing? > A: Top-posting. > Q: What is the most annoying thing on usenet and in e-mail? > > A: No. > Q: Should I include quotations after my reply? > > > On Wed, Apr 26, 2006 at 05:42:44PM +0530, Vishal Sharda wrote: > > > > Yes, I'd seen that but the question is that whether can it be NULL? > > > > I had gone through the function chains from where it is called but > > couldn't find where can it be NULL? > > Are you having a problem with some driver that is causing this to > happen? Or just wanting to figure out why I put a "let's better be safe > than sorry" check in the code? > > thanks, > > greg k-h No, as of now I am not having a problem with any driver. But if you see the code of 2.6.14: if (MAJOR(class_dev->devt)) { struct class_device_attribute *attr; attr = kzalloc(sizeof(*attr), GFP_KERNEL); if (!attr) { error = -ENOMEM; kobject_del(&class_dev->kobj); goto register_done; } attr->attr.name = "dev"; attr->attr.mode = S_IRUGO; ****** attr->attr.owner = parent->owner; attr->show = show_dev; attr->store = NULL; class_device_create_file(class_dev, attr); class_dev->devt_attr = attr; } The code above marked with asterisks could crash the system. So, either there should be a check as it is there at one place in the code in the same function as sown below: if (parent) class_dev->kobj.parent = &parent->subsys.kset.kobj; Or what I think is that probably it is not necessary to check this based on all of the caller function tree I've gone through. Regards, Vishal. **************** CAUTION - Disclaimer ***************** This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended solely for the use of the addressee(s). If you are not the intended recipient, please notify the sender by e-mail and delete the original message. Further, you are not to copy, disclose, or distribute this e-mail or its contents to any other person and any such actions are unlawful. This e-mail may contain viruses. Infosys has taken every reasonable precaution to minimize this risk, but is not liable for any damage you may sustain as a result of any virus in this e-mail. You should carry out your own virus checks before opening the e-mail or attachment. Infosys reserves the right to monitor and review the content of all messages sent to or from this e-mail address. Messages sent to or from this e-mail address may be stored on the Infosys e-mail system. ***INFOSYS******** End of Disclaimer ********INFOSYS*** -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
