[libvirt] [PATCH v2 0/6] nwfilter adjustments for common object
jferlan at redhat.com
Tue Aug 15 01:23:32 UTC 2017
Again, don't bother with patches 4-6.
On 08/02/2017 07:27 AM, John Ferlan wrote:
> ping -
> perhaps at least the first 3...
> I'm now beginning to think/wonder if using the rwlock_rdlock would be
> the solution at least for nwfilter objs. It seems from a quick scan of
> the man page that they are designed to be recursive as long as the
> consumer guarantees that there is an Unlock for every LockRead. A lot
> better than rolling my own recursive lock algorithm that I tried in
> patch 4. Would require some other adjustments (and concessions) along
> the way, but seemingly possible.
> Tks -
> On 07/18/2017 04:57 PM, John Ferlan wrote:
>> v1: https://www.redhat.com/archives/libvir-list/2017-June/msg00079.html
>> Changes since v1 (if I can recall all of them!):
>> Patches 1, 4, 8-13 were pushed
>> Patches 2, 3, 5-7 are dropped
>> This this is a rework of patches 14-17
>> Patch 1 (former patch14):
>> * Requested adjustments made to ACK'd patch, but since this and the
>> remaining ones were related I didn't yet push it.
>> Patch 2 (new):
>> * From review though... As it turns out, virNWFilterDefEqual doesn't
>> require the @cmpUUIDs patch.
>> Patch 3 (fromer patch 15):
>> * Fixed the line as requested. Patch was ACK'd by like Patch 1 I held
>> onto it since it was related.
>> Patch 4 (former patch 16):
>> * Let's call it a complete rewrite. Rather than rely solely on the
>> refcnt of the object, I've added/implemented a 'trylock' mechanism
>> which essentially will allow the subsequent patch to use the
>> virObjectLockable (e.g. a non recursive lock). Of course as I got
>> further into the code - I think I've come to the conclusion that
>> there isn't a way for a @def to disappear between threads with a
>> refcnt only mechanism because there's a few other serialized locks
>> which would need to be hurdled before hand. Still as I found out
>> while running the Avocado test 'nwfilter_update_vm_running.update_arp_rule'
>> the recursion would occur because the AssignDef code would call the
>> Instantiation with the lock from the def being updated and that's
>> where all the awful magic needs to occur. Additionally, I found that
>> one wouldn't want to attempt to lock the nwfilters list inside the
>> virNWFilterObjListFindInstantiateFilter because AssignDef already
>> had that lock. I debated needing a recursive lock there until I
>> came to the conclusion that the list couldn't change because the
>> DefineXML is protected by a driver level lock (as is the Undefine
>> and Reload paths).
>> Patch 5 (former patch 17):
>> * No changes, it was ACK'd, but without 1-4 is useless
>> Patch 6 (NEW):
>> * Remove the need for the driver level lock for a few API's since
>> we have self locking nwfilters list. Also left comments in the
>> 3 places where that lock remained to hopefully cause someone great
>> anxiety if they decided to attempt to remove the lock without
>> first consulting a specialist.
>> NB: Ran all of the changes through the 'nwfilter' tests found in
>> the Avocado test suite.
>> John Ferlan (6):
>> nwfilter: Add @refs logic to __virNWFilterObj
>> nwfilter: Remove unnecessary UUID comparison bypass
>> nwfilter: Convert _virNWFilterObjList to be a virObjectLockable
>> nwfilter: Remove recursive locking for nwfilter instantiation
>> nwfilter: Convert virNWFilterObj to use virObjectLockable
>> nwfilter: Remove need for nwfilterDriverLock in some API's
>> src/conf/virnwfilterobj.c | 635 ++++++++++++++++++++++++---------
>> src/conf/virnwfilterobj.h | 12 +-
>> src/libvirt_private.syms | 6 +-
>> src/nwfilter/nwfilter_driver.c | 66 ++--
>> src/nwfilter/nwfilter_gentech_driver.c | 66 +++-
>> src/util/virobject.c | 24 ++
>> src/util/virobject.h | 4 +
>> src/util/virthread.c | 5 +
>> src/util/virthread.h | 1 +
>> 9 files changed, 586 insertions(+), 233 deletions(-)
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