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Re: [libvirt] [PATCH v3 3/4] monitor: Prevent removing fd from set during init

On 10/17/2012 12:02 AM, Eric Blake wrote:
On 10/16/2012 12:08 PM, Corey Bryant wrote:
If an fd is added to an fd set via the command line, and it is not
referenced by another command line option (ie. -drive), then clean
it up after QEMU initialization is complete.

Signed-off-by: Corey Bryant <coreyb linux vnet ibm com>
   - This patch was split into it's own patch in v3
     (eblake redhat com, kwolf redhat com)

  monitor.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

Reviewed-by: Eric Blake <eblake redhat com>


diff --git a/monitor.c b/monitor.c
index 5d5de41..0dae7ac 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2105,8 +2105,9 @@ static void monitor_fdset_cleanup(MonFdset *mon_fdset)
      MonFdsetFd *mon_fdset_fd_next;

      QLIST_FOREACH_SAFE(mon_fdset_fd, &mon_fdset->fds, next, mon_fdset_fd_next) {
-        if (mon_fdset_fd->removed ||
-                (QLIST_EMPTY(&mon_fdset->dup_fds) && mon_refcount == 0)) {
+        if ((mon_fdset_fd->removed ||
+                (QLIST_EMPTY(&mon_fdset->dup_fds) && mon_refcount == 0)) &&
+                runstate_is_running()) {

This condition looks sufficient for command line parsing; however, I
have to wonder if there are any long-term ill effects, such as if I
pause a guest, then close an fdset, where qemu keeps the fd open until I
continue the guest.  But thinking a bit more, we never promised that
qemu would close fds right away, but only that it wouldn't leak fds by
closing them whenever qemu thinks it is convenient.

I can't think of any ill effects. I think you may be able to remove an fd or fd set followed by adding a drive using that fd set, but that is just a difference in behavior compared to when a guest is running.

              QLIST_REMOVE(mon_fdset_fd, next);

Corey Bryant

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