On 02/16/2018 10:08 AM, Peter Krempa wrote:
On Fri, Feb 16, 2018 at 09:52:53 +0100, Michal Privoznik wrote:
On 02/16/2018 09:34 AM, Pavel Hrdina wrote:
On Mon, Feb 12, 2018 at 01:16:28PM +0100, Michal Privoznik wrote:
On 02/12/2018 01:10 PM, Peter Krempa wrote:
On Mon, Feb 12, 2018 at 11:52:49 +0100, Michal Privoznik wrote:
Sometimes we need the lock in virObjectLockable to be recursive. Because of the nature of pthreads we don't need a special class for that - the pthread_* APIs don't distinguish between normal and recursive locks.
Based-on-work-of: John Ferlan <jferlan@redhat.com> Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/libvirt_private.syms | 1 + src/util/virobject.c | 22 +++++++++++++++++++--- src/util/virobject.h | 4 ++++ 3 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 3b14d7d15..fcf378105 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms
[...]
This can be viewed as rewrite of existing code, not completely new code.
I know that NWFilter code is complex and removing recursive locks is not an easy task, but for the long run I think it's worth it, it will make the code cleaner and easier to follow.
Right, that the ideal goal. But as I said it's far from happening. I think it was you who when trying to fix some issue in NWFilter drew call graph in NWFilter driver and realized how complicated it is. That's why I don't see it happening anywhere in near future. Also, if we really have multiple entry points as Dan mentioned earlier can we really fix this? I mean there are multiple locks that need to be acquired when touching a virNWFilterObj. The advantage of reentrant mutex is that we will not get a dead lock scenario if two functions fight over lock.
Anyway, it's a pity that we are stuck on this patch while reworking the vir*ObjList code.
So and why can't we keep the NWfilter code as-is until the locking is sanitized first? It is working so I don't see a reason to try to rewrite it to objects if it is not trivially possible.
Well, I find it somewhat disappointing. The patches that John and I proposed make things better. But because they don't make it 100% better they are NACKed. But I can live with having two different implementations for vir*ObjList if that's what we want. Or if it's better than having either John's or mines patches merged. I think otherwise though. Michal