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This corrects the test that determines whether a vcpu that has just become able to run in the guest (e.g. it has just finished handling a hypercall or hypervisor page fault) and whose virtual core is already running somewhere as a "piggybacked" vcore can start immediately or not. (A piggybacked vcore is one which is executing along with another vcore as a result of dynamic micro-threading.) Previously the test tried to lock the piggybacked vcore using spin_trylock, which would always fail because the vcore was already locked, and so the vcpu would have to wait until its vcore exited the guest before it could enter. In fact the vcpu can enter if its vcore is in VCORE_PIGGYBACK state and not already exiting (or exited) the guest, so the test in VCORE_PIGGYBACK state is basically the same as for VCORE_RUNNING state. Coverity detected this as a double unlock issue, which it isn't because the spin_trylock would always fail. This will fix the apparent double unlock as well. Signed-off-by: Paul Mackerras <paulus@ozlabs.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.