On Mon, Jun 23, 2025 at 17:17:06 +0100, Daniel P. Berrangé via Devel wrote: > From: Daniel P. Berrangé <berra...@redhat.com> > > The main XML parser code global initializer historically had a mutex > protecting it, and more recently uses a pthread_once. The RelaxNG > code, however, relies on two other global initializers that are > not thread safe, just relying on setting an integer "initialized" > flag. > > Calling the relevant initializers from libvirt in a protected global > initializer will protect libvirt's own concurrent usage, however, it > cannot protect against other libraries loaded in process that might > be using libxml2's schema code. Fortunately: > > * The chances of other loaded non-libvirt code using libxml is > relatively low > * The chances of other loaded non-libvirt code using the schema > validation / catalog functionality inside libxml is even > lower > * The chances of both libvirt and the non-libvirt usage having > their *1st* usage of libxml2 be concurrent is tiny > > IOW, in practice, although our solution doesn't fully fix the thread > safety, it is good enough. > > libxml2 should none the less still be fixed to make its global > initializers be thread safe without special actions by its API > consumers[1]. > > Resolves: https://gitlab.com/libvirt/libvirt/-/issues/788 > [1] https://gitlab.gnome.org/GNOME/libxml2/-/merge_requests/326 > Signed-off-by: Daniel P. Berrangé <berra...@redhat.com> > --- > > Changed in v3: > > - Drop xmlInitializeCatalog - I misread the code wrt > thread safety - it has a sufficiently protective mutex > - Cope with return type change for xmlSchemaInitTypes > in libxml >= 2.11.0
Reviewed-by: Peter Krempa <pkre...@redhat.com>
