External/libvirt
1
0
Fork 0
mirror of https://gitlab.com/libvirt/libvirt.git synced 2024-12-24 14:45:24 +00:00
Code Issues Packages Projects Releases Wiki Activity

virNWFilterBindingObjListAddLocked: Produce better error message than 'Duplicate key'

Browse Source 
If there are two concurrent threads, one of which is removing an
nwfilter from the list and the other is trying to add it back they
may serialize in the following order:

1) obj->removing is set and @obj is unlocked.
2) The tread that's trying to add the nwfilter onto the list locks
   the list and tries to find, if the nwfilter already exists.
3) Our lookup functions say it doesn't, so the thread proceeds to
   virHashAddEntry() which fails with 'Duplicate key' error.

This is obviously not helpful error message at all.

The problem lies in our lookup function
(virNWFilterBindingObjListFindByPortDevLocked()) which return
NULL even if the object is still on the list. They do this so
that the object is not mistakenly looked up by some API. The fix
consists of moving 'removing' check one level up and thus
allowing virNWFilterBindingObjListAddLocked() to produce
meaningful error message.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
This commit is contained in:
Michal Privoznik 2019-03-19 14:39:20 +01:00
parent a5c71129bf
commit b701e45be5
1 changed files with 18 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
src/conf/virnwfilterbindingobjlist.c
View File

@ -91,14 +91,9 @@ virNWFilterBindingObjListFindByPortDevLocked(virNWFilterBindingObjListPtr bindin
virNWFilterBindingObjPtr obj;
obj = virHashLookup(bindings->objs, name);
virObjectRef(obj);
if (obj) {
virObjectRef(obj);
virObjectLock(obj);
if (virNWFilterBindingObjGetRemoving(obj)) {
virObjectUnlock(obj);
virObjectUnref(obj);
obj = NULL;
}
}
return obj;
}
@ -122,6 +117,12 @@ virNWFilterBindingObjListFindByPortDev(virNWFilterBindingObjListPtr bindings,
obj = virNWFilterBindingObjListFindByPortDevLocked(bindings, name);
virObjectRWUnlock(bindings);
if (obj && virNWFilterBindingObjGetRemoving(obj)) {
virObjectUnlock(obj);
virObjectUnref(obj);
obj = NULL;
}
return obj;
}
@ -170,11 +171,17 @@ virNWFilterBindingObjListAddLocked(virNWFilterBindingObjListPtr bindings,
bool stealDef = false;
/* See if a binding with matching portdev already exists */
if ((binding = virNWFilterBindingObjListFindByPortDevLocked(
bindings, def->portdevname))) {
virReportError(VIR_ERR_OPERATION_FAILED,
_("binding '%s' already exists"),
def->portdevname);
binding = virNWFilterBindingObjListFindByPortDevLocked(bindings, def->portdevname);
if (binding) {
if (virNWFilterBindingObjGetRemoving(binding)) {
virReportError(VIR_ERR_OPERATION_FAILED,
_("binding '%s' is already being removed"),
def->portdevname);
} else {
virReportError(VIR_ERR_OPERATION_FAILED,
_("binding '%s' already exists"),
def->portdevname);
}
goto error;
}