Re: [PATCH] qemuNamespaceMknodOne: Call g_file_read_link() in async-signal-safe fashion

When creating a node in QEMU's namespace the whole link chain is created with it. Here, we use g_file_read_link() from the child (running inside the namespace) to learn whether a link exists and points to expected target. Now, when building the namespace there can't be any symlinks and this g_file_read_link() returns NULL always. And because we pass a local GError variable to it, glib tries to set it to a localized error message. This comes with creating a (static) hash table inside of g_strerror() and is guarded with a mutex. The hash table is also allocated using GSlice allocator instead of g_malloc, and since the latter is safe to use after fork (because it's documented to use plain malloc), glib went with the former, naturally. Now, GSlice allocator has plenty of internal mutexes and thus hitting a locked mutex is not that hard. Fortunately, we don't care about any error from g_file_read_link() and thus we can pass NULL which avoids calling g_strerror(). Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2120965 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_namespace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/qemu/qemu_namespace.c b/src/qemu/qemu_namespace.c index a2c31310d9..311c66d46e 100644 --- a/src/qemu/qemu_namespace.c +++ b/src/qemu/qemu_namespace.c @@ -957,10 +957,9 @@ qemuNamespaceMknodOne(qemuNamespaceMknodItem *data) } if (isLink) { - g_autoptr(GError) gerr = NULL; g_autofree char *target = NULL; - if ((target = g_file_read_link(data->file, &gerr)) && + if ((target = g_file_read_link(data->file, NULL)) && STREQ(target, data->target)) { VIR_DEBUG("Skipping symlink %s -> %s which exists and points to correct target", data->file, data->target);