[libvirt] [PATCH 1/2] cgroup: fix including sys/mount.h for OpenBSD

[Roman Bogorodskiy]

  Martin Kletzander wrote:

> On Fri, Jan 08, 2016 at 10:36:07PM +0300, Roman Bogorodskiy wrote:
> >From: Jasper Lievisse Adriaanse <jasper at openbsd.org>
> >
> >Include sys/param.h along with sys/mount.h to fix compilation on
> >OpenBSD.
> >
> >Signed-off-by: Roman Bogorodskiy <bogorodskiy at gmail.com>
> >---
> > src/util/vircgroup.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> >diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
> >index e39c4d1..e8e0875 100644
> >--- a/src/util/vircgroup.c
> >+++ b/src/util/vircgroup.c
> >@@ -27,7 +27,8 @@
> > #if defined HAVE_MNTENT_H && defined HAVE_GETMNTENT_R
> > # include <mntent.h>
> > #endif
> >-#if defined HAVE_SYS_MOUNT_H
> >+#if defined HAVE_SYS_PARAM_H && defined HAVE_SYS_MOUNT_H
> >+# include <sys/param.h>
> > # include <sys/mount.h>
> 
> Wouldn't this cause an error for systems that have sys/mount.h and need
> it for the mount() call, but don't have sys/param.h ?

That's an interesting question.

A check for sys/mount.h was added with the initial implementation of the
mount() using code in commit 1da631e. The mount() call currently is used
only on platforms with cgroups available (i.e. Linux).

Moreover, HAVE_SYS_MOUNT_H does not play any role in cgroups detection:

#if defined(__linux__) && defined(HAVE_GETMNTENT_R) && \
    defined(_DIRENT_HAVE_D_TYPE) && defined(_SC_CLK_TCK)
# define VIR_CGROUP_SUPPORTED
#endif

So, sys/mount.h and mount() are only needed on Linux anyway, and I'm
wondering if we actually can just do something like this:

#if defined HAVE_SYS_MOUNT_H && defined HAVE_GETMNTENT_R
# include <sys/mount.h>
#endif

as if we don't have HAVE_GETMNTENT_R define, we will not have
VIR_CGROUP_SUPPORTED, and therefore we'll not need the mount() call.

I've tested it on FreeBSD and OpenBSD and it builds fine. Unfortunately,
cannot test it on Linux at this moment.

Roman Bogorodskiy