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Using the mtty mdev sample driver we can generate a remove race by starting one shell that continuously creates mtty devices and several other shells all attempting to remove devices, in my case four remove shells. The fault occurs in mdev_remove_sysfs_files() where the passed type arg is NULL, which suggests we've received a struct device in mdev_device_remove() but it's in some sort of teardown state. The solution here is to make use of the accidentally unused list_head on the mdev_device such that the mdev core keeps a list of all the mdev devices. This allows us to validate that we have a valid mdev before we start removal, remove it from the list to prevent others from working on it, and if the vendor driver refuses to remove, we can re-add it to the list. Cc: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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.