On Mon, Nov 18, 2013 at 05:09:31PM +0100, Pavel Hrdina wrote:
On 15.11.2013 17:20, Daniel P. Berrange wrote:
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@redhat.com>
[...]
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) { }
Hi Daniel,
This hunk breaks the build on RHEL-6.4. lxc/lxc_fuse.c:374: error: control reaches end of non-void function [-Wreturn-type]
Fixed as commit 784bb73eaa5507375c21f801376a512dc6ae658d Author: Daniel P. Berrange <berrange@redhat.com> Date: Mon Nov 18 16:12:39 2013 +0000 Add missing 'return 0;' in stub lxcStartFuse() method impl. Without a 'return 0' in the stub lxcStartFuse() method, the compiler warns: lxc/lxc_fuse.c:374: error: control reaches end of non-void function [-Wreturn-type] Signed-off-by: Daniel P. Berrange <berrange@redhat.com> diff --git a/src/lxc/lxc_fuse.c b/src/lxc/lxc_fuse.c index 88e122e..d3d8f85 100644 --- a/src/lxc/lxc_fuse.c +++ b/src/lxc/lxc_fuse.c @@ -371,6 +371,7 @@ int lxcSetupFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED, int lxcStartFuse(virLXCFusePtr f ATTRIBUTE_UNUSED) { + return 0; } void lxcFreeFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED) Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|