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commit 9791ec7df0e7b4d80706ccea8f24b6542f6059e9 upstream. On systems or VMs where multiple devices share a single DevID (because they sit behind a PCI bridge, or because the HW is broken in funky ways), we reuse the save its_device structure in order to reflect this. It turns out that there is a distinct lack of locking when looking up the its_device, and two device being probed concurrently can result in double allocations. That's obviously not nice. A solution for this is to have a per-ITS mutex that serializes device allocation. A similar issue exists on the freeing side, which can run concurrently with the allocation. On top of now taking the appropriate lock, we also make sure that a shared device is never freed, as we have no way to currently track the life cycle of such object. Reported-by: Zheng Xiang <zhengxiang9@huawei.com> Tested-by: Zheng Xiang <zhengxiang9@huawei.com> Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.