On 01/16/2018 06:08 AM, Paolo Bonzini wrote:
There are cases in which a queued coroutine must be restarted from non-coroutine context (with qemu_co_enter_next). In this cases, qemu_co_enter_next also needs to be thread-safe, but it cannot use a CoMutex and so cannot qemu_co_queue_wait. This happens in curl (which right now is rolling its own list of Coroutines) and will happen in Fam's NVMe driver as well. This series extracts the idea of a polymorphic lockable object from my "scoped lock guard" proposal, and applies it to CoQueue. The implementation of QemuLockable is similar to C11 _Generic, but redone using the preprocessor and GCC builtins for compatibility. In general, while a bit on the esoteric side, the functionality used to emulate _Generic is fairly old in GCC, and the builtins are already used by include/qemu/atomic.h; the series was tested with Fedora 27 (boot Damn Small Linux via http) and CentOS 6 (compiled only).
Reviewed-by: Fam Zheng <f...@redhat.com>
