[CRIU] [PATCH 09/10] epoll: Ignore inaccessible targets

[Kirill Tkhai]

On 28.02.2017 18:05, Cyrill Gorcunov wrote:
> Not all targets can be restored by now,
> so simply ignore them on dump this should
> not be a common case.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> ---
>  criu/eventpoll.c      | 57 +++++++++++++++++++++++++++++++++++++++++----------
>  criu/include/fdinfo.h |  1 +
>  criu/proc_parse.c     |  1 +
>  3 files changed, 48 insertions(+), 11 deletions(-)
> 
> diff --git a/criu/eventpoll.c b/criu/eventpoll.c
> index 0515b736603a..670cb06f95bd 100644
> --- a/criu/eventpoll.c
> +++ b/criu/eventpoll.c
> @@ -151,6 +151,7 @@ int dump_eventpoll(void)
>  	struct kid_elem *kid;
>  
>  	list_for_each_entry(dinfo, &eventpoll_fds, list) {
> +		unsigned long nr_valid = 0;
>  		kcmp_epoll_slot_t slot = {
>  			.efd	= dinfo->fd,
>  			.toff	= 0,
> @@ -167,22 +168,56 @@ int dump_eventpoll(void)
>  				kid = fd_kid_epoll_lookup(dinfo->pid,
>  							  te->epl.gen_id,
>  							  &slot);
> -				if (!kid || kid->pid != dinfo->pid) {
> -					pr_err("Target %d not found for pid %d "
> -					       "(or pid mismatsh %d)\n",
> -					       te->epl.e.tfd, dinfo->pid,
> -					       kid ? kid->pid : -1);
> -					goto out;
> +				if (!kid || kid->pid != dinfo->pid ||
> +				    kid->idx != te->epl.e.tfd) {
> +					pr_warn("Target %d not found for pid %d "
> +						"(or pid mismatsh %d), ignoring\n",
> +						te->epl.e.tfd, dinfo->pid,
> +						kid ? kid->pid : -1);
> +					te->epl.valid = 0;
> +				} else {
> +					pr_debug("Target %d for pid %d matched fd %d\n",
> +						 te->epl.e.tfd, dinfo->pid, kid->idx);
> +					nr_valid++;
> +				}
> +			} else {
> +				char path[PATH_MAX];
> +
> +				snprintf(path, sizeof(path), "/proc/%d/fd/%d",
> +					 dinfo->pid, slot.tfd);
> +				if (access(path, F_OK)) {
> +					pr_warn("Target %d not found for pid %d, ignoring\n",
> +						te->epl.e.tfd, dinfo->pid);
> +					te->epl.valid = 0;
> +				} else {
> +					pr_debug("Target %d for pid %d is accessible\n",
> +						 te->epl.e.tfd, dinfo->pid);
> +					nr_valid++;
>  				}
> -
> -				pr_debug("Target %d for pid %d matched fd %d\n",
> -					 te->epl.e.tfd, dinfo->pid, kid->idx);
>  			}
> +		}
> +
> +		if (nr_valid != dinfo->efe.n_tfd) {
> +			size_t i = 0;
>  
> -			if (pb_write_one(img_from_set(glob_imgset, CR_FD_EVENTPOLL_FILE),
> -					 &dinfo->efe, PB_EVENTPOLL_FILE))
> +			EventpollTfdEntry **tfd = xmalloc(sizeof(struct EventpollTfdEntry *) * nr_valid);


> +			if (!tfd)
>  				goto out;
> +
> +			list_for_each_entry(te, &dinfo->ep_list, epl.node) {
> +				if (te->epl.valid)
> +					tfd[i++] = &te->epl.e;
> +			}
> +
> +			xfree(dinfo->efe.tfd);
> +			dinfo->efe.tfd = tfd;
> +			dinfo->efe.n_tfd = nr_valid;
>  		}
> +
> +		pr_info_eventpoll("Dumping ", &dinfo->efe);
> +		if (pb_write_one(img_from_set(glob_imgset, CR_FD_EVENTPOLL_FILE),
> +				 &dinfo->efe, PB_EVENTPOLL_FILE))

Have you checked that this works correct, when nr_valid == 0 and tfd == NULL?

> +			goto out;
>  	}
>  
>  	ret = 0;
> diff --git a/criu/include/fdinfo.h b/criu/include/fdinfo.h
> index be516efce5d6..c9af47eeadc5 100644
> --- a/criu/include/fdinfo.h
> +++ b/criu/include/fdinfo.h
> @@ -30,6 +30,7 @@ struct eventpoll_tfd_entry {
>  	struct list_head node;
>  	unsigned int gen_id;
>  	int use_kcmp;
> +	int valid;
>  };
>  
>  union fdinfo_entries {
> diff --git a/criu/proc_parse.c b/criu/proc_parse.c
> index a96123679aa2..f2255d42e6f7 100644
> --- a/criu/proc_parse.c
> +++ b/criu/proc_parse.c
> @@ -1744,6 +1744,7 @@ static int parse_fdinfo_pid_s(int pid, int fd, int type,
>  			e = xmalloc(sizeof(union fdinfo_entries));
>  			if (!e)
>  				goto out;
> +			e->epl.valid = 1;
>  
>  			eventpoll_tfd_entry__init(&e->epl.e);
>  
>