[lxc-devel] [PATCH] cgroup.c: clean up for handle_cgroup_settings

[Serge Hallyn]

Quoting Qiang Huang (h.huangqiang at huawei.com):
> Ping...
> 
> Hi Serge or Stéphane,
> 
> Did you miss this?

Patch looks good,

Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

but note that the there's been a touch of churn there.  If ok with
you I'll apply your patch with the needed changes;  if you prefer to
send a new patch let me know.

> On 2014/1/20 16:37, Qiang Huang wrote:
> > Clean up the nesting if, make the logic similar for memory
> > and cpuset, and the error message should sent from inside,
> > for better extendibility.
> > 
> > Signed-off-by: Qiang Huang <h.huangqiang at huawei.com>
> > ---
> >  src/lxc/cgroup.c | 53 ++++++++++++++++++++++++++++++++++-------------------
> >  1 file changed, 34 insertions(+), 19 deletions(-)
> > 
> > diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
> > index 85384fc..693db94 100644
> > --- a/src/lxc/cgroup.c
> > +++ b/src/lxc/cgroup.c
> > @@ -782,10 +782,8 @@ struct cgroup_process_info *lxc_cgroupfs_create(const char *name, const char *pa
> > 
> >  		if (lxc_string_in_array("ns", (const char **)h->subsystems))
> >  			continue;
> > -		if (handle_cgroup_settings(mp, info_ptr->cgroup_path) < 0) {
> > -			ERROR("Could not set clone_children to 1 for cpuset hierarchy in parent cgroup.");
> > +		if (handle_cgroup_settings(mp, info_ptr->cgroup_path) < 0)
> >  			goto out_initial_error;
> > -		}
> >  	}
> > 
> >  	/* normalize the path */
> > @@ -2016,43 +2014,60 @@ static int handle_cgroup_settings(struct cgroup_mount_point *mp,
> >  {
> >  	int r, saved_errno = 0;
> >  	char buf[2];
> > +	const char **subsystems = (const char **)mp->hierarchy->subsystems;
> > 
> >  	/* If this is the memory cgroup, we want to enforce hierarchy.
> >  	 * But don't fail if for some reason we can't.
> >  	 */
> > -	if (lxc_string_in_array("memory", (const char **)mp->hierarchy->subsystems)) {
> > -		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path, "/memory.use_hierarchy");
> > -		if (cc_path) {
> > -			r = lxc_read_from_file(cc_path, buf, 1);
> > -			if (r < 1 || buf[0] != '1') {
> > -				r = lxc_write_to_file(cc_path, "1", 1, false);
> > -				if (r < 0)
> > -					SYSERROR("failed to set memory.use_hiararchy to 1; continuing");
> > -			}
> > +	if (lxc_string_in_array("memory", subsystems)) {
> > +		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path,
> > +						"/memory.use_hierarchy");
> > +		if (!cc_path)
> > +			goto cpuset;
> > +
> > +		r = lxc_read_from_file(cc_path, buf, 1);
> > +		if (r == 1 && buf[0] == '1') {
> >  			free(cc_path);
> > +			goto cpuset;
> >  		}
> > +
> > +		r = lxc_write_to_file(cc_path, "1", 1, false);
> > +		if (r < 0)
> > +			SYSERROR("Failed to set memory.use_hiararchy to 1; continuing");
> > +		free(cc_path);
> >  	}
> > 
> >  	/* if this is a cpuset hierarchy, we have to set cgroup.clone_children in
> >  	 * the base cgroup, otherwise containers will start with an empty cpuset.mems
> >  	 * and cpuset.cpus and then
> >  	 */
> > -	if (lxc_string_in_array("cpuset", (const char **)mp->hierarchy->subsystems)) {
> > -		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path, "/cgroup.clone_children");
> > +cpuset:
> > +	if (lxc_string_in_array("cpuset", subsystems)) {
> > +		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path,
> > +						"/cgroup.clone_children");
> >  		if (!cc_path)
> > -			return -1;
> > +			goto err;
> > +
> >  		r = lxc_read_from_file(cc_path, buf, 1);
> >  		if (r == 1 && buf[0] == '1') {
> >  			free(cc_path);
> > -			return 0;
> > +			goto out;
> >  		}
> > +
> >  		r = lxc_write_to_file(cc_path, "1", 1, false);
> > -		saved_errno = errno;
> > +		if (r < 0) {
> > +			SYSERROR("Failed to set clone_children to 1 for cpuset hierarchy in parent cgroup.");
> > +			saved_errno = errno;
> > +			free(cc_path);
> > +			errno = saved_errno;
> > +			goto err;
> > +		}
> >  		free(cc_path);
> > -		errno = saved_errno;
> > -		return r < 0 ? -1 : 0;
> >  	}
> > +out:
> >  	return 0;
> > +err:
> > +	return -1;
> >  }
> > 
> >  extern void lxc_monitor_send_state(const char *name, lxc_state_t state,
> > 
> 
>