Commit id '46a811db07' added code to check if the filter by Name already existed with a different UUID, to go along with the existing found filter by UUID and compare the Names match thus making it impossible to reach this find by Name condition without both the Name and UUID already matching, so remove the need to "filter" out the UUID for the virNWFilterDefEqual. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/conf/virnwfilterobj.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) diff --git a/src/conf/virnwfilterobj.c b/src/conf/virnwfilterobj.c index 408e575ca..87d7e7270 100644 --- a/src/conf/virnwfilterobj.c +++ b/src/conf/virnwfilterobj.c @@ -287,18 +287,11 @@ virNWFilterObjTestUnassignDef(virNWFilterObjPtr obj) static bool virNWFilterDefEqual(const virNWFilterDef *def1, - virNWFilterDefPtr def2, - bool cmpUUIDs) + virNWFilterDefPtr def2) { bool ret = false; - unsigned char rem_uuid[VIR_UUID_BUFLEN]; - char *xml1, *xml2 = NULL; - - if (!cmpUUIDs) { - /* make sure the UUIDs are equal */ - memcpy(rem_uuid, def2->uuid, sizeof(rem_uuid)); - memcpy(def2->uuid, def1->uuid, sizeof(def2->uuid)); - } + char *xml1 = NULL; + char *xml2 = NULL; if (!(xml1 = virNWFilterDefFormat(def1)) || !(xml2 = virNWFilterDefFormat(def2))) @@ -307,9 +300,6 @@ virNWFilterDefEqual(const virNWFilterDef *def1, ret = STREQ(xml1, xml2); cleanup: - if (!cmpUUIDs) - memcpy(def2->uuid, rem_uuid, sizeof(rem_uuid)); - VIR_FREE(xml1); VIR_FREE(xml2); @@ -360,7 +350,7 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, if ((obj = virNWFilterObjListFindByName(nwfilters, def->name))) { objdef = obj->def; - if (virNWFilterDefEqual(def, objdef, false)) { + if (virNWFilterDefEqual(def, objdef)) { virNWFilterDefFree(objdef); obj->def = def; return obj; -- 2.13.6

On 12/08/2017 09:01 AM, John Ferlan wrote: Sorry, but difficult to parse this sentence. Thinking out lout here (and below): virNWFilterDefFormat() will write the UUID into the XML. The STREQ will only ever be equal if def1 and def2 have the same UUID. We will not get here if a filter with the same uuid and name exists or same name and different uuid. So we can have the same uuid and a different name at this point. This call doesn't need to 'shadow' the uuid. It's the only caller. so your change seems to be correct. Reviewed-by: Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt;

Unlike it's counterparts, the nwfilter object code needs to be able to support recursive read locks while processing and checking new filters against the existing environment. Thus instead of using a virObjectLockable which uses pure mutexes, use the virObjectRWLockable and primarily use RWLockRead when obtaining the object lock since RWLockRead locks can be recursively obtained (up to a limit) as long as there's a corresponding unlock. Since all the object management is within the virnwfilterobj code, we can limit the number of Write locks on the object to very small areas of code to ensure we don't run into deadlock's with other threads and domain code that will check/use the filters (it's a very delicate balance). This limits the write locks to AssignDef and Remove processing. This patch will introduce a new API virNWFilterObjEndAPI to unlock and deref the object. This patch introduces two helpers to promote/demote the read/write lock. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/conf/virnwfilterobj.c | 191 +++++++++++++++++++++++---------- src/conf/virnwfilterobj.h | 9 +- src/libvirt_private.syms | 3 +- src/nwfilter/nwfilter_driver.c | 15 +-- src/nwfilter/nwfilter_gentech_driver.c | 11 +- 5 files changed, 149 insertions(+), 80 deletions(-) diff --git a/src/conf/virnwfilterobj.c b/src/conf/virnwfilterobj.c index 87d7e7270..6b4758656 100644 --- a/src/conf/virnwfilterobj.c +++ b/src/conf/virnwfilterobj.c @@ -34,7 +34,7 @@ VIR_LOG_INIT("conf.virnwfilterobj"); struct _virNWFilterObj { - virMutex lock; + virObjectRWLockable parent; bool wantRemoved; @@ -47,27 +47,69 @@ struct _virNWFilterObjList { virNWFilterObjPtr *objs; }; +static virClassPtr virNWFilterObjClass; +static void virNWFilterObjDispose(void *opaque); + + +static int +virNWFilterObjOnceInit(void) +{ + if (!(virNWFilterObjClass = virClassNew(virClassForObjectRWLockable(), + "virNWFilterObj", + sizeof(virNWFilterObj), + virNWFilterObjDispose))) + return -1; + + return 0; +} + +VIR_ONCE_GLOBAL_INIT(virNWFilterObj) + static virNWFilterObjPtr virNWFilterObjNew(void) { virNWFilterObjPtr obj; - if (VIR_ALLOC(obj) < 0) + if (virNWFilterObjInitialize() < 0) return NULL; - if (virMutexInitRecursive(&obj->lock) < 0) { - virReportError(VIR_ERR_INTERNAL_ERROR, - "%s", _("cannot initialize mutex")); - VIR_FREE(obj); + if (!(obj = virObjectRWLockableNew(virNWFilterObjClass))) return NULL; - } - virNWFilterObjLock(obj); + virObjectRWLockWrite(obj); return obj; } +static void +virNWFilterObjPromoteToWrite(virNWFilterObjPtr obj) +{ + virObjectRWUnlock(obj); + virObjectRWLockWrite(obj); +} + + +static void +virNWFilterObjDemoteFromWrite(virNWFilterObjPtr obj) +{ + virObjectRWUnlock(obj); + virObjectRWLockRead(obj); +} + + +void +virNWFilterObjEndAPI(virNWFilterObjPtr *obj) +{ + if (!*obj) + return; + + virObjectRWUnlock(*obj); + virObjectUnref(*obj); + *obj = NULL; +} + + virNWFilterDefPtr virNWFilterObjGetDef(virNWFilterObjPtr obj) { @@ -90,17 +132,15 @@ virNWFilterObjWantRemoved(virNWFilterObjPtr obj) static void -virNWFilterObjFree(virNWFilterObjPtr obj) +virNWFilterObjDispose(void *opaque) { + virNWFilterObjPtr obj = opaque; + if (!obj) return; virNWFilterDefFree(obj->def); virNWFilterDefFree(obj->newDef); - - virMutexDestroy(&obj->lock); - - VIR_FREE(obj); } @@ -109,7 +149,7 @@ virNWFilterObjListFree(virNWFilterObjListPtr nwfilters) { size_t i; for (i = 0; i < nwfilters->count; i++) - virNWFilterObjFree(nwfilters->objs[i]); + virObjectUnref(nwfilters->objs[i]); VIR_FREE(nwfilters->objs); VIR_FREE(nwfilters); } @@ -132,22 +172,32 @@ virNWFilterObjListRemove(virNWFilterObjListPtr nwfilters, { size_t i; - virNWFilterObjUnlock(obj); + virObjectRWUnlock(obj); for (i = 0; i < nwfilters->count; i++) { - virNWFilterObjLock(nwfilters->objs[i]); + virObjectRWLockWrite(nwfilters->objs[i]); if (nwfilters->objs[i] == obj) { - virNWFilterObjUnlock(nwfilters->objs[i]); - virNWFilterObjFree(nwfilters->objs[i]); + virObjectRWUnlock(nwfilters->objs[i]); + virObjectUnref(nwfilters->objs[i]); VIR_DELETE_ELEMENT(nwfilters->objs, i, nwfilters->count); break; } - virNWFilterObjUnlock(nwfilters->objs[i]); + virObjectRWUnlock(nwfilters->objs[i]); } } +/** + * virNWFilterObjListFindByUUID + * @nwfilters: Pointer to filter list + * @uuid: UUID to use to lookup the object + * + * Search for the object by uuidstr in the hash table and return a read + * locked copy of the object. + * + * Returns: A reffed and read locked object or NULL on error + */ virNWFilterObjPtr virNWFilterObjListFindByUUID(virNWFilterObjListPtr nwfilters, const unsigned char *uuid) @@ -158,17 +208,27 @@ virNWFilterObjListFindByUUID(virNWFilterObjListPtr nwfilters, for (i = 0; i < nwfilters->count; i++) { obj = nwfilters->objs[i]; - virNWFilterObjLock(obj); + virObjectRWLockRead(obj); def = obj->def; if (!memcmp(def->uuid, uuid, VIR_UUID_BUFLEN)) - return obj; - virNWFilterObjUnlock(obj); + return virObjectRef(obj); + virObjectRWUnlock(obj); } return NULL; } +/** + * virNWFilterObjListFindByName + * @nwfilters: Pointer to filter list + * @name: filter name to use to lookup the object + * + * Search for the object by name in the hash table and return a read + * locked copy of the object. + * + * Returns: A reffed and read locked object or NULL on error + */ virNWFilterObjPtr virNWFilterObjListFindByName(virNWFilterObjListPtr nwfilters, const char *name) @@ -179,11 +239,11 @@ virNWFilterObjListFindByName(virNWFilterObjListPtr nwfilters, for (i = 0; i < nwfilters->count; i++) { obj = nwfilters->objs[i]; - virNWFilterObjLock(obj); + virObjectRWLockRead(obj); def = obj->def; if (STREQ_NULLABLE(def->name, name)) - return obj; - virNWFilterObjUnlock(obj); + return virObjectRef(obj); + virObjectRWUnlock(obj); } return NULL; @@ -205,8 +265,7 @@ virNWFilterObjListFindInstantiateFilter(virNWFilterObjListPtr nwfilters, if (virNWFilterObjWantRemoved(obj)) { virReportError(VIR_ERR_NO_NWFILTER, _("Filter '%s' is in use."), filtername); - virNWFilterObjUnlock(obj); - return NULL; + virNWFilterObjEndAPI(&obj); } return obj; @@ -240,7 +299,7 @@ _virNWFilterObjListDefLoopDetect(virNWFilterObjListPtr nwfilters, if (obj) { rc = _virNWFilterObjListDefLoopDetect(nwfilters, obj->def, filtername); - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); if (rc < 0) break; } @@ -269,17 +328,36 @@ virNWFilterObjListDefLoopDetect(virNWFilterObjListPtr nwfilters, } +/* virNWFilterObjTestUnassignDef + * @obj: A read locked nwfilter object + * + * Cause the rebuild to occur because we're about to undefine the nwfilter. + * The rebuild code is designed to check if the filter is currently in use + * by a domain and thus disallow the unassign. + * + * NB: Although we enter with the UPDATE lock from UNDEFINE, let's still + * promote to a WRITE lock before changing *this* object's wantRemoved + * value that will be used in the virNWFilterObjListFindInstantiateFilter + * processing to determine whether we can really remove this filter or not. + * + * Returns 0 if we can continue with the unassign, -1 if it's in use + */ int virNWFilterObjTestUnassignDef(virNWFilterObjPtr obj) { int rc = 0; + virNWFilterObjPromoteToWrite(obj); obj->wantRemoved = true; + virNWFilterObjDemoteFromWrite(obj); + /* trigger the update on VMs referencing the filter */ if (virNWFilterTriggerVMFilterRebuild() < 0) rc = -1; + virNWFilterObjPromoteToWrite(obj); obj->wantRemoved = false; + virNWFilterObjDemoteFromWrite(obj); return rc; } @@ -322,10 +400,10 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, _("filter with same UUID but different name " "('%s') already exists"), objdef->name); - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return NULL; } - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); } else { if ((obj = virNWFilterObjListFindByName(nwfilters, def->name))) { char uuidstr[VIR_UUID_STRING_BUFLEN]; @@ -335,7 +413,7 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, virReportError(VIR_ERR_OPERATION_FAILED, _("filter '%s' already exists with uuid %s"), def->name, uuidstr); - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return NULL; } } @@ -347,7 +425,10 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, } + /* Get a READ lock and immediately promote to WRITE while we adjust + * data within. */ if ((obj = virNWFilterObjListFindByName(nwfilters, def->name))) { + virNWFilterObjPromoteToWrite(obj); objdef = obj->def; if (virNWFilterDefEqual(def, objdef)) { @@ -357,13 +438,20 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, } obj->newDef = def; + + /* Demote while the trigger runs since it may need to grab a read + * lock on this object and promote before returning. */ + virNWFilterObjDemoteFromWrite(obj); + /* trigger the update on VMs referencing the filter */ if (virNWFilterTriggerVMFilterRebuild() < 0) { + virNWFilterObjPromoteToWrite(obj); obj->newDef = NULL; - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return NULL; } + virNWFilterObjPromoteToWrite(obj); virNWFilterDefFree(objdef); obj->def = def; obj->newDef = NULL; @@ -375,13 +463,12 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, if (VIR_APPEND_ELEMENT_COPY(nwfilters->objs, nwfilters->count, obj) < 0) { - virNWFilterObjUnlock(obj); - virNWFilterObjFree(obj); + virNWFilterObjEndAPI(&obj); return NULL; } obj->def = def; - return obj; + return virObjectRef(obj); } @@ -395,10 +482,10 @@ virNWFilterObjListNumOfNWFilters(virNWFilterObjListPtr nwfilters, for (i = 0; i < nwfilters->count; i++) { virNWFilterObjPtr obj = nwfilters->objs[i]; - virNWFilterObjLock(obj); + virObjectRWLockRead(obj); if (!filter || filter(conn, obj->def)) nfilters++; - virNWFilterObjUnlock(obj); + virObjectRWUnlock(obj); } return nfilters; @@ -418,16 +505,16 @@ virNWFilterObjListGetNames(virNWFilterObjListPtr nwfilters, for (i = 0; i < nwfilters->count && nnames < maxnames; i++) { virNWFilterObjPtr obj = nwfilters->objs[i]; - virNWFilterObjLock(obj); + virObjectRWLockRead(obj); def = obj->def; if (!filter || filter(conn, def)) { if (VIR_STRDUP(names[nnames], def->name) < 0) { - virNWFilterObjUnlock(obj); + virObjectRWUnlock(obj); goto failure; } nnames++; } - virNWFilterObjUnlock(obj); + virObjectRWUnlock(obj); } return nnames; @@ -464,16 +551,16 @@ virNWFilterObjListExport(virConnectPtr conn, for (i = 0; i < nwfilters->count; i++) { obj = nwfilters->objs[i]; - virNWFilterObjLock(obj); + virObjectRWLockRead(obj); def = obj->def; if (!filter || filter(conn, def)) { if (!(nwfilter = virGetNWFilter(conn, def->name, def->uuid))) { - virNWFilterObjUnlock(obj); + virObjectRWUnlock(obj); goto cleanup; } tmp_filters[nfilters++] = nwfilter; } - virNWFilterObjUnlock(obj); + virObjectRWUnlock(obj); } *filters = tmp_filters; @@ -551,24 +638,10 @@ virNWFilterObjListLoadAllConfigs(virNWFilterObjListPtr nwfilters, continue; obj = virNWFilterObjListLoadConfig(nwfilters, configDir, entry->d_name); - if (obj) - virNWFilterObjUnlock(obj); + + virNWFilterObjEndAPI(&obj); } VIR_DIR_CLOSE(dir); return ret; } - - -void -virNWFilterObjLock(virNWFilterObjPtr obj) -{ - virMutexLock(&obj->lock); -} - - -void -virNWFilterObjUnlock(virNWFilterObjPtr obj) -{ - virMutexUnlock(&obj->lock); -} diff --git a/src/conf/virnwfilterobj.h b/src/conf/virnwfilterobj.h index 8e79518ed..0281bc5f5 100644 --- a/src/conf/virnwfilterobj.h +++ b/src/conf/virnwfilterobj.h @@ -41,6 +41,9 @@ struct _virNWFilterDriverState { bool watchingFirewallD; }; +void +virNWFilterObjEndAPI(virNWFilterObjPtr *obj); + virNWFilterDefPtr virNWFilterObjGetDef(virNWFilterObjPtr obj); @@ -105,10 +108,4 @@ int virNWFilterObjListLoadAllConfigs(virNWFilterObjListPtr nwfilters, const char *configDir); -void -virNWFilterObjLock(virNWFilterObjPtr obj); - -void -virNWFilterObjUnlock(virNWFilterObjPtr obj); - #endif /* VIRNWFILTEROBJ_H */ diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index de4ec4d44..132244878 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1022,6 +1022,7 @@ virNodeDeviceObjListRemove; # conf/virnwfilterobj.h +virNWFilterObjEndAPI; virNWFilterObjGetDef; virNWFilterObjGetNewDef; virNWFilterObjListAssignDef; @@ -1035,9 +1036,7 @@ virNWFilterObjListLoadAllConfigs; virNWFilterObjListNew; virNWFilterObjListNumOfNWFilters; virNWFilterObjListRemove; -virNWFilterObjLock; virNWFilterObjTestUnassignDef; -virNWFilterObjUnlock; virNWFilterObjWantRemoved; diff --git a/src/nwfilter/nwfilter_driver.c b/src/nwfilter/nwfilter_driver.c index 885dbcc28..b38740b15 100644 --- a/src/nwfilter/nwfilter_driver.c +++ b/src/nwfilter/nwfilter_driver.c @@ -400,7 +400,7 @@ nwfilterLookupByUUID(virConnectPtr conn, nwfilter = virGetNWFilter(conn, def->name, def->uuid); cleanup: - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return nwfilter; } @@ -430,7 +430,7 @@ nwfilterLookupByName(virConnectPtr conn, nwfilter = virGetNWFilter(conn, def->name, def->uuid); cleanup: - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return nwfilter; } @@ -517,6 +517,8 @@ nwfilterDefineXML(virConnectPtr conn, if (virNWFilterSaveConfig(driver->configDir, objdef) < 0) { virNWFilterObjListRemove(driver->nwfilters, obj); + virObjectUnref(obj); + obj = NULL; goto cleanup; } @@ -524,8 +526,7 @@ nwfilterDefineXML(virConnectPtr conn, cleanup: virNWFilterDefFree(def); - if (obj) - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); virNWFilterCallbackDriversUnlock(); virNWFilterUnlockFilterUpdates(); @@ -563,12 +564,12 @@ nwfilterUndefine(virNWFilterPtr nwfilter) goto cleanup; virNWFilterObjListRemove(driver->nwfilters, obj); + virObjectUnref(obj); obj = NULL; ret = 0; cleanup: - if (obj) - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); virNWFilterCallbackDriversUnlock(); virNWFilterUnlockFilterUpdates(); @@ -601,7 +602,7 @@ nwfilterGetXMLDesc(virNWFilterPtr nwfilter, ret = virNWFilterDefFormat(def); cleanup: - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return ret; } diff --git a/src/nwfilter/nwfilter_gentech_driver.c b/src/nwfilter/nwfilter_gentech_driver.c index 840d419bb..48d0e1769 100644 --- a/src/nwfilter/nwfilter_gentech_driver.c +++ b/src/nwfilter/nwfilter_gentech_driver.c @@ -316,7 +316,7 @@ virNWFilterInstReset(virNWFilterInstPtr inst) size_t i; for (i = 0; i < inst->nfilters; i++) - virNWFilterObjUnlock(inst->filters[i]); + virNWFilterObjEndAPI(&inst->filters[i]); VIR_FREE(inst->filters); inst->nfilters = 0; @@ -426,8 +426,7 @@ virNWFilterIncludeDefToRuleInst(virNWFilterDriverStatePtr driver, if (ret < 0) virNWFilterInstReset(inst); virNWFilterHashTableFree(tmpvars); - if (obj) - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return ret; } @@ -541,7 +540,7 @@ virNWFilterDetermineMissingVarsRec(virNWFilterDefPtr filter, /* create a temporary hashmap for depth-first tree traversal */ if (!(tmpvars = virNWFilterCreateVarsFrom(inc->params, vars))) { - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); return -1; } @@ -565,7 +564,7 @@ virNWFilterDetermineMissingVarsRec(virNWFilterDefPtr filter, virNWFilterHashTableFree(tmpvars); - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); if (rc < 0) return -1; } @@ -839,7 +838,7 @@ virNWFilterInstantiateFilterUpdate(virNWFilterDriverStatePtr driver, virNWFilterHashTableFree(vars1); err_exit: - virNWFilterObjUnlock(obj); + virNWFilterObjEndAPI(&obj); VIR_FREE(str_ipaddr); VIR_FREE(str_macaddr); -- 2.13.6

On 01/31/2018 09:15 PM, Stefan Berger wrote: It's "hidden" by that VIR_ONCE_GLOBAL_INIT macro... Fairly common when using referenced object classes. See src/util/virthread.h. Essentially a common way of handling a lockable object - if you search on vir.*ObjNew (where .* is domain, interface, network, nodedevice, secret, storagevol, and storagepool) you'll see a common theme. Also a bit of paranoia. Since the nwfilters list will eventually be write locked too during add, it shouldn't really matter. We only ever do this when adding a new nwfilter. The two existing callers of virNWFilterObjListAssignDef are virNWFilterObjListLoadConfig via virNWFilterObjListLoadAllConfigs and nwfilterDefineXML do not demote the lock from write to read. Both end up calling virNWFilterObjEndAPI to release the lock when they're done. That's my assumption on this too - trying to get read-locks refcnt to zero. If there were a bunch of readers, then obtaining the write lock will wait for all those readers to complete. If we were the only reader, then getting the write will happen. It would be really nice to have the dlm available - that code was generated using the OpenVMS lock manager which I actually got to know quite well in a previous job... In the long run, I believe this ends up being one of those pthread_rwlock_wrlock type "things" related to refcnt's and which thread we're talking about. The man page states: "The pthread_rwlock_wrlock() function applies a write lock to the read-write lock referenced by rwlock. The calling thread acquires the write lock if no other thread (reader or writer) holds the read-write lock rwlock. Otherwise, the thread blocks (that is, does not return from the pthread_rwlock_wrlock() call) until it can acquire the lock. Results are undefined if the calling thread holds the read-write lock (whether a read or write lock) at the time the call is made." So my "choice" is demote/promote mainly because of that "undefined" part and because of other 'research' which seemed to indicate that promoting to wr while holding rd doesn't work reliably. This code essentially mirrors how other vir.*ObjListRemove API's handle removing an object from the List (or what eventually will be a Hash Table). I agree that getting the lock is superfluous, but to a degree this change is part of an overall larger set of changes (already complete) that have converted from linked lists to hash tables. The nwfilter code has lagged because no one really wants to look at it! True for now, but in two patches, that lock is removed. In the next patch the nwfilters gets rwlock capabilities too. Maybe once all this is done - I can go back and remove all the unnecessary Lock/Unlock once list is RWLock'd. Yes, this has been a painful exercise... The domain code still is messed up, but that's a different problem. We do, see virNWFilterObjEndAPI, after it Unref and Unlock it: *obj = NULL; thus obj = NULL when we leave. Every time we call virNWFilterObjListFindByName we return with a locked and reffed @obj. Once we are done with that obj, we have to remove the lock and ref. It's a fairly common process with all the other driver code. True that could/should be done since we're no longer updating @obj. I can add that. This one I'm not sure I agree as what we're doing then is: Unlock(WR) Lock(RD) Unlock(RD) Instead of just Unlock(WR) I'm not 100% against it, but I'm not sure I see the reason. How about if I add before the EndAPI: /* NB: We're done, no need to Demote and End, just End */ Sure... Technically we wouldn't need the else if the if returns NULL... True, but that is handled that way in the next patch (essentially). I'll make the change for clarity in this patch though. Thanks for the review... I appreciate it especially since nwfilter has languished in this "project" I undertook a bit over a year ago to convert driver objects to using objects/classes and hash tables instead of VIR_ALLOC[_N] and forward linked lists... It's the last code to convert although domainobj[list] processing still doesn't 100% use the style. Not sure if I still have the same energy/desire to tackle domain though. John

Implement the self locking object list for nwfilter object lists that uses two hash tables to store the nwfilter object by UUID or by Name. As part of this alter the uuid argument to virNWFilterObjLookupByUUID to expect an already formatted uuidstr. Alter the existing list traversal code to implement the hash table find/lookup/search functionality. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/conf/virnwfilterobj.c | 402 ++++++++++++++++++++++++++++------------- src/conf/virnwfilterobj.h | 2 +- src/nwfilter/nwfilter_driver.c | 5 +- 3 files changed, 282 insertions(+), 127 deletions(-) diff --git a/src/conf/virnwfilterobj.c b/src/conf/virnwfilterobj.c index 6b4758656..a4e6a03d2 100644 --- a/src/conf/virnwfilterobj.c +++ b/src/conf/virnwfilterobj.c @@ -43,12 +43,21 @@ struct _virNWFilterObj { }; struct _virNWFilterObjList { - size_t count; - virNWFilterObjPtr *objs; + virObjectRWLockable parent; + + /* uuid string -> virNWFilterObj mapping + * for O(1), lockless lookup-by-uuid */ + virHashTable *objs; + + /* name -> virNWFilterObj mapping for O(1), + * lockless lookup-by-name */ + virHashTable *objsName; }; static virClassPtr virNWFilterObjClass; +static virClassPtr virNWFilterObjListClass; static void virNWFilterObjDispose(void *opaque); +static void virNWFilterObjListDispose(void *opaque); static int @@ -60,6 +69,12 @@ virNWFilterObjOnceInit(void) virNWFilterObjDispose))) return -1; + if (!(virNWFilterObjListClass = virClassNew(virClassForObjectRWLockable(), + "virNWFilterObjList", + sizeof(virNWFilterObjList), + virNWFilterObjListDispose))) + return -1; + return 0; } @@ -144,14 +159,20 @@ virNWFilterObjDispose(void *opaque) } +static void +virNWFilterObjListDispose(void *opaque) +{ + virNWFilterObjListPtr nwfilters = opaque; + + virHashFree(nwfilters->objs); + virHashFree(nwfilters->objsName); +} + + void virNWFilterObjListFree(virNWFilterObjListPtr nwfilters) { - size_t i; - for (i = 0; i < nwfilters->count; i++) - virObjectUnref(nwfilters->objs[i]); - VIR_FREE(nwfilters->objs); - VIR_FREE(nwfilters); + virObjectUnref(nwfilters); } @@ -160,8 +181,23 @@ virNWFilterObjListNew(void) { virNWFilterObjListPtr nwfilters; - if (VIR_ALLOC(nwfilters) < 0) + if (virNWFilterObjInitialize() < 0) + return NULL; + + if (!(nwfilters = virObjectRWLockableNew(virNWFilterObjListClass))) + return NULL; + + if (!(nwfilters->objs = virHashCreate(10, virObjectFreeHashData))) { + virObjectUnref(nwfilters); + return NULL; + } + + if (!(nwfilters->objsName = virHashCreate(10, virObjectFreeHashData))) { + virHashFree(nwfilters->objs); + virObjectUnref(nwfilters); return NULL; + } + return nwfilters; } @@ -170,83 +206,105 @@ void virNWFilterObjListRemove(virNWFilterObjListPtr nwfilters, virNWFilterObjPtr obj) { - size_t i; - - virObjectRWUnlock(obj); + char uuidstr[VIR_UUID_STRING_BUFLEN]; + virNWFilterDefPtr def; - for (i = 0; i < nwfilters->count; i++) { - virObjectRWLockWrite(nwfilters->objs[i]); - if (nwfilters->objs[i] == obj) { - virObjectRWUnlock(nwfilters->objs[i]); - virObjectUnref(nwfilters->objs[i]); + if (!obj) + return; + def = obj->def; - VIR_DELETE_ELEMENT(nwfilters->objs, i, nwfilters->count); - break; - } - virObjectRWUnlock(nwfilters->objs[i]); - } + virUUIDFormat(def->uuid, uuidstr); + virObjectRef(obj); + virObjectRWUnlock(obj); + virObjectRWLockWrite(nwfilters); + virObjectRWLockWrite(obj); + virHashRemoveEntry(nwfilters->objs, uuidstr); + virHashRemoveEntry(nwfilters->objsName, def->name); + virObjectRWUnlock(obj); + virObjectUnref(obj); + virObjectRWUnlock(nwfilters); } /** - * virNWFilterObjListFindByUUID + * virNWFilterObjListFindByUUID[Locked] * @nwfilters: Pointer to filter list - * @uuid: UUID to use to lookup the object + * @uuidstr: UUID to use to lookup the object + * + * The static [Locked] version would only be used when the Object List is + * already locked, such as is the case during virNWFilterObjListAssignDef. + * The caller is thus responsible for locking the object. * * Search for the object by uuidstr in the hash table and return a read * locked copy of the object. * + * Returns: A reffed object or NULL on error + */ +static virNWFilterObjPtr +virNWFilterObjListFindByUUIDLocked(virNWFilterObjListPtr nwfilters, + const char *uuidstr) +{ + return virObjectRef(virHashLookup(nwfilters->objs, uuidstr)); +} + + +/* * Returns: A reffed and read locked object or NULL on error */ virNWFilterObjPtr virNWFilterObjListFindByUUID(virNWFilterObjListPtr nwfilters, - const unsigned char *uuid) + const char *uuidstr) { - size_t i; virNWFilterObjPtr obj; - virNWFilterDefPtr def; - for (i = 0; i < nwfilters->count; i++) { - obj = nwfilters->objs[i]; + virObjectRWLockRead(nwfilters); + obj = virNWFilterObjListFindByUUIDLocked(nwfilters, uuidstr); + virObjectRWUnlock(nwfilters); + if (obj) virObjectRWLockRead(obj); - def = obj->def; - if (!memcmp(def->uuid, uuid, VIR_UUID_BUFLEN)) - return virObjectRef(obj); - virObjectRWUnlock(obj); - } - return NULL; + return obj; } /** - * virNWFilterObjListFindByName + * virNWFilterObjListFindByName[Locked] * @nwfilters: Pointer to filter list * @name: filter name to use to lookup the object * + * The static [Locked] version would only be used when the Object List is + * already locked, such as is the case during virNWFilterObjListAssignDef. + * The caller is thus responsible for locking the object. + * * Search for the object by name in the hash table and return a read * locked copy of the object. * + * Returns: A reffed object or NULL on error + */ +static virNWFilterObjPtr +virNWFilterObjListFindByNameLocked(virNWFilterObjListPtr nwfilters, + const char *name) +{ + return virObjectRef(virHashLookup(nwfilters->objsName, name)); +} + + +/* * Returns: A reffed and read locked object or NULL on error */ virNWFilterObjPtr virNWFilterObjListFindByName(virNWFilterObjListPtr nwfilters, const char *name) { - size_t i; virNWFilterObjPtr obj; - virNWFilterDefPtr def; - for (i = 0; i < nwfilters->count; i++) { - obj = nwfilters->objs[i]; + virObjectRWLockRead(nwfilters); + obj = virNWFilterObjListFindByNameLocked(nwfilters, name); + virObjectRWUnlock(nwfilters); + if (obj) virObjectRWLockRead(obj); - def = obj->def; - if (STREQ_NULLABLE(def->name, name)) - return virObjectRef(obj); - virObjectRWUnlock(obj); - } - return NULL; + return obj; } @@ -391,8 +449,11 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, { virNWFilterObjPtr obj; virNWFilterDefPtr objdef; + char uuidstr[VIR_UUID_STRING_BUFLEN]; - if ((obj = virNWFilterObjListFindByUUID(nwfilters, def->uuid))) { + virUUIDFormat(def->uuid, uuidstr); + + if ((obj = virNWFilterObjListFindByUUID(nwfilters, uuidstr))) { objdef = obj->def; if (STRNEQ(def->name, objdef->name)) { @@ -406,10 +467,7 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, virNWFilterObjEndAPI(&obj); } else { if ((obj = virNWFilterObjListFindByName(nwfilters, def->name))) { - char uuidstr[VIR_UUID_STRING_BUFLEN]; - objdef = obj->def; - virUUIDFormat(objdef->uuid, uuidstr); virReportError(VIR_ERR_OPERATION_FAILED, _("filter '%s' already exists with uuid %s"), def->name, uuidstr); @@ -424,11 +482,13 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, return NULL; } - - /* Get a READ lock and immediately promote to WRITE while we adjust - * data within. */ - if ((obj = virNWFilterObjListFindByName(nwfilters, def->name))) { - virNWFilterObjPromoteToWrite(obj); + /* We're about to make some changes to objects on the list - so get + * the list READ lock in order to Find the object and WRITE lock it + * while we adjust data within. */ + virObjectRWLockRead(nwfilters); + if ((obj = virNWFilterObjListFindByNameLocked(nwfilters, def->name))) { + virObjectRWUnlock(nwfilters); + virObjectRWLockWrite(obj); objdef = obj->def; if (virNWFilterDefEqual(def, objdef)) { @@ -458,37 +518,112 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters, return obj; } + /* Promote the nwfilters to add a new object */ + virObjectRWUnlock(nwfilters); + virObjectRWLockWrite(nwfilters); if (!(obj = virNWFilterObjNew())) - return NULL; + goto cleanup; - if (VIR_APPEND_ELEMENT_COPY(nwfilters->objs, - nwfilters->count, obj) < 0) { - virNWFilterObjEndAPI(&obj); - return NULL; + if (virHashAddEntry(nwfilters->objs, uuidstr, obj) < 0) + goto error; + virObjectRef(obj); + + if (virHashAddEntry(nwfilters->objsName, def->name, obj) < 0) { + virHashRemoveEntry(nwfilters->objs, uuidstr); + goto error; } + virObjectRef(obj); + obj->def = def; - return virObjectRef(obj); + cleanup: + virObjectRWUnlock(nwfilters); + return obj; + + error: + virObjectRWUnlock(obj); + virObjectUnref(obj); + virObjectRWUnlock(nwfilters); + return NULL; } +struct virNWFilterCountData { + virConnectPtr conn; + virNWFilterObjListFilter filter; + int nelems; +}; + +static int +virNWFilterObjListNumOfNWFiltersCallback(void *payload, + const void *name ATTRIBUTE_UNUSED, + void *opaque) +{ + virNWFilterObjPtr obj = payload; + struct virNWFilterCountData *data = opaque; + + virObjectRWLockRead(obj); + if (!data->filter || data->filter(data->conn, obj->def)) + data->nelems++; + virObjectRWUnlock(obj); + return 0; +} + int virNWFilterObjListNumOfNWFilters(virNWFilterObjListPtr nwfilters, virConnectPtr conn, virNWFilterObjListFilter filter) { - size_t i; - int nfilters = 0; + struct virNWFilterCountData data = { .conn = conn, + .filter = filter, .nelems = 0 }; - for (i = 0; i < nwfilters->count; i++) { - virNWFilterObjPtr obj = nwfilters->objs[i]; - virObjectRWLockRead(obj); - if (!filter || filter(conn, obj->def)) - nfilters++; - virObjectRWUnlock(obj); + virObjectRWLockRead(nwfilters); + virHashForEach(nwfilters->objs, virNWFilterObjListNumOfNWFiltersCallback, + &data); + virObjectRWUnlock(nwfilters); + + return data.nelems; +} + + +struct virNWFilterListData { + virConnectPtr conn; + virNWFilterObjListFilter filter; + int nelems; + char **elems; + int maxelems; + bool error; +}; + +static int +virNWFilterObjListGetNamesCallback(void *payload, + const void *name ATTRIBUTE_UNUSED, + void *opaque) +{ + virNWFilterObjPtr obj = payload; + virNWFilterDefPtr def; + struct virNWFilterListData *data = opaque; + + if (data->error) + return 0; + + if (data->maxelems >= 0 && data->nelems == data->maxelems) + return 0; + + virObjectRWLockRead(obj); + def = obj->def; + + if (!data->filter || data->filter(data->conn, def)) { + if (VIR_STRDUP(data->elems[data->nelems], def->name) < 0) { + data->error = true; + goto cleanup; + } + data->nelems++; } - return nfilters; + cleanup: + virObjectRWUnlock(obj); + return 0; } @@ -499,82 +634,103 @@ virNWFilterObjListGetNames(virNWFilterObjListPtr nwfilters, char **const names, int maxnames) { - int nnames = 0; - size_t i; - virNWFilterDefPtr def; + struct virNWFilterListData data = { .conn = conn, .filter = filter, + .nelems = 0, .elems = names, .maxelems = maxnames, .error = false }; - for (i = 0; i < nwfilters->count && nnames < maxnames; i++) { - virNWFilterObjPtr obj = nwfilters->objs[i]; - virObjectRWLockRead(obj); - def = obj->def; - if (!filter || filter(conn, def)) { - if (VIR_STRDUP(names[nnames], def->name) < 0) { - virObjectRWUnlock(obj); - goto failure; - } - nnames++; - } - virObjectRWUnlock(obj); - } + virObjectRWLockRead(nwfilters); + virHashForEach(nwfilters->objs, virNWFilterObjListGetNamesCallback, &data); + virObjectRWUnlock(nwfilters); - return nnames; + if (data.error) + goto error; - failure: - while (--nnames >= 0) - VIR_FREE(names[nnames]); + return data.nelems; + error: + while (--data.nelems >= 0) + VIR_FREE(data.elems[data.nelems]); return -1; } +struct virNWFilterExportData { + virConnectPtr conn; + virNWFilterObjListFilter filter; + virNWFilterPtr *filters; + int nfilters; + bool error; +}; + +static int +virNWFilterObjListExportCallback(void *payload, + const void *name ATTRIBUTE_UNUSED, + void *opaque) +{ + virNWFilterObjPtr obj = payload; + virNWFilterDefPtr def; + + struct virNWFilterExportData *data = opaque; + virNWFilterPtr nwfilter; + + if (data->error) + return 0; + + virObjectRWLockRead(obj); + def = obj->def; + + if (data->filter && !data->filter(data->conn, def)) + goto cleanup; + + if (!data->filters) { + data->nfilters++; + goto cleanup; + } + + if (!(nwfilter = virGetNWFilter(data->conn, def->name, def->uuid))) { + data->error = true; + goto cleanup; + } + data->filters[data->nfilters++] = nwfilter; + + cleanup: + virObjectRWUnlock(obj); + return 0; +} + + int virNWFilterObjListExport(virConnectPtr conn, virNWFilterObjListPtr nwfilters, virNWFilterPtr **filters, virNWFilterObjListFilter filter) { - virNWFilterPtr *tmp_filters = NULL; - int nfilters = 0; - virNWFilterPtr nwfilter = NULL; - virNWFilterObjPtr obj = NULL; - virNWFilterDefPtr def; - size_t i; - int ret = -1; + struct virNWFilterExportData data = { .conn = conn, .filter = filter, + .filters = NULL, .nfilters = 0, .error = false }; - if (!filters) { - ret = nwfilters->count; - goto cleanup; + virObjectRWLockRead(nwfilters); + if (filters && + VIR_ALLOC_N(data.filters, virHashSize(nwfilters->objs) + 1) < 0) { + virObjectRWUnlock(nwfilters); + return -1; } - if (VIR_ALLOC_N(tmp_filters, nwfilters->count + 1) < 0) - goto cleanup; + virHashForEach(nwfilters->objs, virNWFilterObjListExportCallback, &data); + virObjectRWUnlock(nwfilters); - for (i = 0; i < nwfilters->count; i++) { - obj = nwfilters->objs[i]; - virObjectRWLockRead(obj); - def = obj->def; - if (!filter || filter(conn, def)) { - if (!(nwfilter = virGetNWFilter(conn, def->name, def->uuid))) { - virObjectRWUnlock(obj); - goto cleanup; - } - tmp_filters[nfilters++] = nwfilter; - } - virObjectRWUnlock(obj); + if (data.error) + goto cleanup; + + if (data.filters) { + /* trim the array to the final size */ + ignore_value(VIR_REALLOC_N(data.filters, data.nfilters + 1)); + *filters = data.filters; } - *filters = tmp_filters; - tmp_filters = NULL; - ret = nfilters; + return data.nfilters; cleanup: - if (tmp_filters) { - for (i = 0; i < nfilters; i ++) - virObjectUnref(tmp_filters[i]); - } - VIR_FREE(tmp_filters); - - return ret; + virObjectListFree(data.filters); + return -1; } diff --git a/src/conf/virnwfilterobj.h b/src/conf/virnwfilterobj.h index 0281bc5f5..cabb42a71 100644 --- a/src/conf/virnwfilterobj.h +++ b/src/conf/virnwfilterobj.h @@ -65,7 +65,7 @@ virNWFilterObjListRemove(virNWFilterObjListPtr nwfilters, virNWFilterObjPtr virNWFilterObjListFindByUUID(virNWFilterObjListPtr nwfilters, - const unsigned char *uuid); + const char *uuidstr); virNWFilterObjPtr virNWFilterObjListFindByName(virNWFilterObjListPtr nwfilters, diff --git a/src/nwfilter/nwfilter_driver.c b/src/nwfilter/nwfilter_driver.c index b38740b15..b24f59379 100644 --- a/src/nwfilter/nwfilter_driver.c +++ b/src/nwfilter/nwfilter_driver.c @@ -369,11 +369,10 @@ nwfilterObjFromNWFilter(const unsigned char *uuid) virNWFilterObjPtr obj; char uuidstr[VIR_UUID_STRING_BUFLEN]; - if (!(obj = virNWFilterObjListFindByUUID(driver->nwfilters, uuid))) { - virUUIDFormat(uuid, uuidstr); + virUUIDFormat(uuid, uuidstr); + if (!(obj = virNWFilterObjListFindByUUID(driver->nwfilters, uuidstr))) virReportError(VIR_ERR_NO_NWFILTER, _("no nwfilter with matching uuid '%s'"), uuidstr); - } return obj; } -- 2.13.6

On 01/31/2018 10:10 PM, Stefan Berger wrote: [1] As part of the magic of hash tables, when an element is removed from the hash table the virObjectFreeHashData is called which does a virObjectUnref... [1] So when we RemoveEntry, the data->tableFree (from our Create) is called. So, yes, that Unref happens automagically. Once the last ref is removed the object's disposal API (virNWFilterObjDispose) is called before being completely reaped. Hmm... true... I think that's because originally I had done the list patch before the object patch... So it's probably one of those merge things... Good catch. Right. That was the "end goal"... I've never seen a consistent style for these things, but I can move the .conn to the same line as .filter which is done in other initializers where there is only one line. Thanks! Yes, the error would be we cannot shrink... This is common between vir.*ObjList.*Export.* functions Thanks again for the detailed review. After I push patch 1, I'll repost the remaining ones. Maybe Laine will also have some luck with his nwfilter testing. He's pursuing either a locking problem or a *severe* performance problem with the libvirt-tck test. John

[...] Revisiting this particular place after some testing I've just done using the libvirt-tck test... and lots of debug code ;-)... When we return from the FindByNameLocked, all we have is a refcnt incremented object. So, we have to Lock it while we still hold the nwfilters read lock, thus this particular hunk was "mostly" correct. ... Should have taken the lock while we had nwfilters lock ... Using a Write lock avoids the immediate promote in either path [...] I'm going to post a v5 soon with the adjustments. I also added one more place to Demote in the new series. That'd be in the end of this AssignDef where we get a new filter to be consistent we should return with the filter read locked only. John

On 12/08/2017 09:01 AM, John Ferlan wrote: This looks good.