Re: [libvirt] [PATCH] Avoid async signal safety problem in glibc's setxid

The glibc setxid is supposed to be async signal safe, but libc developers confirm that it is not. This causes a problem when libvirt_lxc starts the FUSE thread and then runs clone() to start the container. If the clone() was done before the FUSE thread has completely started up, then the container will hang in setxid after clone(). The fix is to avoid creating any threads until after the container has been clone()'d. By avoiding any threads in the parent, the child is no longer required to run in an async signal safe context, and we thus avoid the glibc bug. Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt;

diff --git a/src/lxc/lxc_fuse.c b/src/lxc/lxc_fuse.c index 9d12832..88e122e 100644 --- a/src/lxc/lxc_fuse.c +++ b/src/lxc/lxc_fuse.c

@@ -364,6 +369,10 @@ int lxcSetupFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED, return 0; } +int lxcStartFuse(virLXCFusePtr f ATTRIBUTE_UNUSED) +{ +} + void lxcFreeFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED) { }