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    SubjectRE: [PATCH v10 13/15] platform/x86: wmi: create userspace interface for drivers
    Date
    > -----Original Message-----
    > From: Greg KH [mailto:greg@kroah.com]
    > Sent: Friday, October 20, 2017 8:22 AM
    > To: Limonciello, Mario <Mario_Limonciello@Dell.com>
    > Cc: dvhart@infradead.org; Andy Shevchenko <andy.shevchenko@gmail.com>;
    > LKML <linux-kernel@vger.kernel.org>; platform-driver-x86@vger.kernel.org; Andy
    > Lutomirski <luto@kernel.org>; quasisec@google.com; pali.rohar@gmail.com;
    > rjw@rjwysocki.net; mjg59@google.com; hch@lst.de; Alan Cox
    > <gnomes@lxorguk.ukuu.org.uk>
    > Subject: Re: [PATCH v10 13/15] platform/x86: wmi: create userspace interface for
    > drivers
    >
    > On Thu, Oct 19, 2017 at 12:50:16PM -0500, Mario Limonciello wrote:
    > > + wblock = container_of(wdev, struct wmi_block, dev);
    > > + if (!wblock)
    > > + return -ENODEV;
    >
    > How can container_of() ever return NULL? If so, you have a very odd
    > memory layout...
    >

    I'm assuming this is from set_required_buffer_size right?

    The symbol is exported out for other drivers to use. It's possible for another
    driver to allocate a wmi_device structure that's not part of a wblock.

    > > + list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
    > > + wdriver = container_of(wblock->dev.dev.driver,
    > > + struct wmi_driver, driver);
    > > + if (!wdriver)
    > > + continue;
    >
    > Same here. And other places in this file.
    >

    This one it's possible that a driver isn't bound to a device, and when
    that happens wdriver is NULL.

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