[CRIU] [PATCH 5/5] pstree: use rbtree to find a specified pid

[Andrew Vagin]

On Wed, Mar 09, 2016 at 02:03:34PM +0300, Pavel Emelyanov wrote:
> On 02/19/2016 09:13 PM, Andrey Vagin wrote:
> > From: Andrew Vagin <avagin at virtuozzo.com>
> > 
> > Signed-off-by: Andrew Vagin <avagin at virtuozzo.com>
> > ---
> >  criu/pstree.c | 36 +++++++++++++++++++++++++-----------
> >  1 file changed, 25 insertions(+), 11 deletions(-)
> > 
> > diff --git a/criu/pstree.c b/criu/pstree.c
> > index 61fd5d3..f82a3de 100644
> > --- a/criu/pstree.c
> > +++ b/criu/pstree.c
> > @@ -383,6 +383,23 @@ static int prepare_pstree_for_shell_job(void)
> >  	return 0;
> >  }
> >  
> > +static struct pid *lookup_pid(pid_t pid)
> 
> We already have pstree_item_by_virt and pstree_item_by_real. Why do we need one more?

"struct pid" is used for threads too
> 
> > +{
> > +	struct rb_node *node = root_rb.rb_node;
> > +
> > +	while (node) {
> > +		struct pid *this = rb_entry(node, struct pid, node);
> > +
> > +		if (pid < this->virt)
> > +			node = node->rb_left;
> > +		else if (pid > this->virt)
> > +			node = node->rb_right;
> > +		else
> > +			return this;
> > +	}
> > +	return NULL;
> > +}
> > +
> >  static struct pid *insert_pid(pid_t pid, struct pid *pid_node)
> >  {
> >  	struct rb_node *node = root_rb.rb_node;
> > @@ -686,18 +703,15 @@ static int prepare_pstree_ids(void)
> >  
> >  	/* Add a process group leader if it is absent  */
> >  	for_each_pstree_item(item) {
> > -		struct pstree_item *gleader;
> > +		struct pid *pid;
> >  
> >  		if (!item->pgid || item->pid.virt == item->pgid)
> >  			continue;
> >  
> > -		for_each_pstree_item(gleader) {
> > -			if (gleader->pid.virt == item->pgid)
> > -				break;
> > -		}
> > -
> > -		if (gleader) {
> > -			rsti(item)->pgrp_leader = gleader;
> > +		pid = lookup_pid(item->pgid);
> > +		if (pid->state != TASK_UNDEF) {
> > +			BUG_ON(pid->state == TASK_THREAD);
> > +			rsti(item)->pgrp_leader = container_of(pid, struct pstree_item, pid);
> >  			continue;
> >  		}
> >  
> > @@ -709,9 +723,9 @@ static int prepare_pstree_ids(void)
> >  		if (current_pgid == item->pgid)
> >  			continue;
> >  
> > -		helper = alloc_pstree_helper();
> > -		if (helper == NULL)
> > -			return -1;
> > +		helper = container_of(pid, struct pstree_item, pid);
> > +		init_pstree_helper(helper);
> > +
> >  		helper->sid = item->sid;
> >  		helper->pgid = item->pgid;
> >  		helper->pid.virt = item->pgid;
> > 
>