[Libvir] [PATCH] lxc: handle SIGCHLD from exiting container

[Jim Meyering]

Dave Leskovec <dlesko at linux.vnet.ibm.com> wrote:
...
>>> +#ifndef	_SIGNAL_H
>>> +#include <signal.h>
>>> +#endif
>>
>> In practice it's fine to include <signal.h> unconditionally,
>> and even multiple times.  Have you encountered a version of <signal.h>
>> that may not be included twice?  If so, it probably deserves a comment
>> with the details.
>
> No, I don't have any special condition here.  This is probably some past
> conditioning resurfacing briefly.  If I remember correctly, it had more to do
> with compile efficiency rather than avoiding compile failures from multiple
> inclusions.

Then don't bother.
gcc performs a handy optimization whereby it doesn't even open
the header file the second (and subsequent) time it's included, as
long as it's entire contents is wrapped in the usual sort of guard:

  #ifndef SYM
  #define SYM
  ...
  #endif