On 08/16/2012 05:07 PM, Eric Blake wrote:
On 08/09/2012 09:20 AM, Daniel P. Berrange wrote:
From: "Daniel P. Berrange" <berrange@redhat.com>
Add two new APIs virLockSpaceNewPostExecRestart and virLockSpacePreExecRestart which allow a virLockSpacePtr object to be created from a JSON object and saved to a JSON object, for the purposes of re-exec'ing a process.
As well as saving the state in JSON format, the second method will disable the O_CLOEXEC flag so that the open file descriptors are preserved across the process re-exec()
Signed-off-by: Daniel P. Berrange <berrange@redhat.com> ---
Is virLockSpacePreExecRestart called in the parent prior to forking (mostly good, with one caveat) or in the child between fork and exec (bad, since you malloc and do a lot of other non-async-safe stuff)? If the latter, we risk deadlock; if the former, then you have at least one bug...
Before you worry about responding to this, read my comments on 21/23. I think I've managed to convince myself that if these functions are only ever called from virtlockd (and _not_ from libvirt.so or libvirtd), then the fact that virtlockd is so dedicated-purpose as to never spawn a helper child means that you don't have to worry about FD_CLOEXEC races to arbitrary children. If you agree with my analysis, then this patch (and several like it where I complained about CLOEXEC races) should be okay as-is. -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org