[libvirt] [PATCH v2 0/2] Rework reference counting in QEMU

Our reference locking for objects is great and powerful thing. The problem is that it was either not followed through completely or the design was not complete, but it doesn't matter now. There are few bugs in the code due to the reference counting and the daemon is lacking some performance in specific scenarios. This "series" tried to fix that using the following idea: - Each API working with a domain object that has to get it from the list will have its *own* reference, not borrowed one from the list. - When adding a domain into the list, the reference counter is increased (this is the reference that is there just for being in the list) and when being removed, it is decreased. No special-casing of "if this is was the last reference" and other funny stuff. - When job is created, there is no need to increase the reference counter as there are at least two references for the domain: 1) The API that created the job has one, so if it's not async it will be kept until the API ends and at that point the job won't exist any more. 2) The domain list has one and even though I said nobody needs to rely on that, async APIs probably will do that, but there's an excuse for that. In order to remove the domain from the list, you need a job and that won't succeed unless the async one ended. So we're good in this case as well. After searching through the code for all things that needed to be removed and fixing everything I could possibly think of, I tried a few things on my setup and it looks like it works. However, I haven't tried *every single API*, but I hope that's understandable. On the other hand, I asked Pavel to try running virt-test with these patches applied, hopefully we'll get an idea about how reliable this "series" is. I used "series" (with quotes) on purpose, because first patch just adds two new wrappers for slightly modified function and the second one changes the whole qemu driver at once. Unfortunately the second patch couldn't be broken up to more parts due to the nature of the fix. Martin Kletzander (2): conf: Rework virDomainObjListFindByUUID to allow more concurrent APIs qemu: completely rework reference counting src/conf/domain_conf.c | 29 +- src/conf/domain_conf.h | 2 + src/libvirt_private.syms | 1 + src/qemu/THREADS.txt | 40 ++- src/qemu/qemu_domain.c | 49 ++-- src/qemu/qemu_domain.h | 12 +- src/qemu/qemu_driver.c | 708 ++++++++++++++++------------------------------ src/qemu/qemu_migration.c | 111 +++----- src/qemu/qemu_migration.h | 10 +- src/qemu/qemu_process.c | 77 ++--- 10 files changed, 400 insertions(+), 639 deletions(-) -- 2.2.0