On a Thursday in 2022, Daniel P. Berrangé wrote:
The comment against the 'updateMutex' refers to a problem with lock ordering when looking up filters in the virNWFilterObjList which uses an array. That problem does indeed exist.
Unfortunately it claims that switching to a hash table would solve the lock ordering problems during instantiation. That is not correct because there is a second lock ordering problem related to how we traverse related filters when instantiating filters. Consider a set of filters:
Filter A: Reference Filter C Reference Filter D
Filter B: Reference Filter D Reference Filter C
In one example, we lock A, C, D, in the other example we lock A, D, C.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- src/nwfilter/nwfilter_gentech_driver.c | 57 ++++++++++++++++++++------ 1 file changed, 45 insertions(+), 12 deletions(-)
Reviewed-by: Ján Tomko <jtomko@redhat.com> Jano