On 01/25/2018 11:59 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). > > Paolo > > v1->v2: fix typos and copyright year > > v2->v3: add tests, fix brown paper bag bug, avoid -Waddress errors
I spotted a few typos, but did not rigorously test it enough to leave R-b. At any rate, writing polymorphic code in C is an interesting exercise, so it was fun learning from this thread. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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