[CRIU] [PATCH v5 08/11] unix: Resolve senders of packets in receive queue of DGRAM socket
Pavel Emelyanov
xemul at virtuozzo.com
Tue Jun 28 05:19:46 PDT 2016
On 06/16/2016 04:54 PM, Kirill Tkhai wrote:
> Determine unique senders of packets in receive queue. If sender
> is the only or if queue is empty, try to assign a queuer.
> If there are several senders or if it's impossible to assign
> a queuer, request the sender fle to be sent to task, who restores
> the socket.
>
> In resolve_unix_peers(), there are the second iteration thru
> unix_sockets. It's need to set peers of rest sockets: sockets
> who are not queuer of someone. I do not merge it in the single
> iteration, because of optimization reasons. The most sockets
> should have peers set after the first iteration, so to call
> find_unix_sk_by_ino() one more time is excess.
>
> v5: Use fle to send promious queue's senders.
> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
> criu/sk-unix.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 143 insertions(+), 13 deletions(-)
>
> diff --git a/criu/sk-unix.c b/criu/sk-unix.c
> index 959b30d..b221a71 100644
> --- a/criu/sk-unix.c
> +++ b/criu/sk-unix.c
> @@ -28,6 +28,7 @@
> #include "namespaces.h"
> #include "pstree.h"
> #include "crtools.h"
> +#include "rst-malloc.h"
>
> #include "protobuf.h"
> #include "images/sk-unix.pb-c.h"
> @@ -1334,7 +1335,7 @@ static int collect_one_unixsk(void *o, ProtobufCMessage *base, struct cr_img *i)
> ui->ue = pb_msg(base, UnixSkEntry);
> ui->name_dir = (void *)ui->ue->name_dir;
>
> - if (ui->ue->peer && !post_queued) {
> + if (!post_queued) {
> post_queued = true;
> if (add_post_prepare_cb(resolve_unix_peers, NULL))
> return -1;
> @@ -1392,11 +1393,152 @@ static void interconnected_pair(struct unix_sk_info *ui, struct unix_sk_info *pe
> }
> }
>
> +static int set_queuer(u32 s_ino, struct unix_sk_info *r_ui, unsigned count)
> +{
> + u32 r_ino = r_ui->ue->ino;
> + struct unix_sk_info *s_ui;
> +
> + list_for_each_entry(s_ui, &unix_sockets, list) {
This drives us into O(n^2) of unix peers resolution :(
> + if (s_ui->ue->peer != r_ino)
> + continue;
> + /*
> + * Currently, only DGRAM senders are dumped,
> + * while others always have zero s_ino here.
> + * For DGRAM, zero s_ino means "unnamed sender".
> + */
> + if (s_ino && s_ino != s_ui->ue->ino)
> + continue;
> + /* Looking for unnamed sender, while s_ui is not */
> + if (r_ui->ue->type == SOCK_DGRAM &&
> + !s_ino && count && s_ui->ue->name.len)
> + continue;
> + s_ui->peer = r_ui;
> + r_ui->queuer = s_ui->ue->ino;
> +
> + /* socket connected to self %) */
> + if (s_ui == r_ui)
> + continue;
> +
> + if (s_ui->queuer == r_ino)
> + interconnected_pair(s_ui, r_ui);
> + return 0;
> + }
> + return -1;
> +}
> +
> +static int add_receiver(u32 s_ino, struct unix_sk_info *r_ui)
> +{
> + struct fdinfo_list_entry *s_fle, *r_fle;
> + struct pstree_item *r_task;
> + struct unix_sk_info *s_ui;
> + int fd;
> +
> + if (!s_ino)
> + return 0;
> +
> + s_ui = find_unix_sk_by_ino(s_ino);
> + if (!s_ui) {
> + pr_err("Can't find a sender: ino=%d\n", s_ino);
> + return -1;
> + }
> +
> + r_fle = file_master(&r_ui->d);
> + r_task = pstree_item_by_virt(r_fle->pid);
> + if (!r_task) {
> + pr_err("Can't find task by vpid %u\n", r_fle->pid);
> + return -1;
> + }
> +
> + list_for_each_entry(s_fle, &s_ui->d.fd_info_head, desc_list) {
> + /* Return, if receiver task already owns this socket */
> + if (s_fle->pid == r_task->pid.virt)
> + return 0;
> + }
> +
> + fd = find_unused_fd(&rsti(r_task)->used, -1);
> + s_fle = file_master(&s_ui->d);
> +
> + s_fle = dup_fle(r_task, s_fle, fd, s_fle->fe->flags);
> + if (!s_fle) {
> + pr_err("Can't dup sock fle\n");
> + return -1;
> + }
> + s_fle->flags |= FD_LE_GHOST;
> +
> + pr_info("Add receiver %u to %u\n", r_ui->ue->ino, s_ino);
> +
> + return 0;
> +}
> +
> +/*
> + * Resolves senders and returns number of foreign senders, we should receive.
> + */
> +static int resolve_senders(struct unix_sk_info *r_ui)
> +{
> + struct sk_packet *pkt;
> + u32 s_ino, *sa = NULL;
> + int i, ret, count = 0;
> +
> + list_for_each_entry(pkt, &packets_list, list) {
> + SkPacketEntry *entry = pkt->entry;
> + bool found = false;
> +
> + if (entry->id_for != r_ui->ue->id)
> + continue;
> + if (entry->has_sender_ino)
> + s_ino = entry->sender_ino;
> + else
> + s_ino = 0;
> +
> + for (i = 0; i < count; i++) {
> + if (sa[i] == s_ino) {
> + found = true;
> + break;
> + }
> + }
> +
> + if (found)
> + continue;
> +
> + count++;
> + sa = xrealloc(sa, sizeof(u32) * count);
> + if (!sa)
> + goto err;
> + sa[count-1] = s_ino;
> + }
> +
> + if (count <= 1) {
> + s_ino = count ? sa[0] : 0;
> + ret = set_queuer(s_ino, r_ui, count);
> + if (ret == 0 || !count || r_ui->ue->type != SOCK_DGRAM)
> + goto out;
On ret == -1 you _may_ go ahead and try the for() loop below? Why? It's an error already.
> + }
> +
> + BUG_ON(r_ui->ue->type != SOCK_DGRAM || !count);
> +
> + for (i = 0; i < count; i++) {
> + ret = add_receiver(sa[i], r_ui);
> + if (ret < 0)
> + goto err;
> + }
> +out:
> + xfree(sa);
> + return 0;
> +err:
> + pr_err("Resolving senders failed\n");
> + return -1;
> +}
> +
> static int resolve_unix_peers(void *unused)
> {
> struct unix_sk_info *ui, *peer;
>
> list_for_each_entry(ui, &unix_sockets, list) {
> + if (resolve_senders(ui) < 0)
> + return -1;
> + }
> +
> + list_for_each_entry(ui, &unix_sockets, list) {
Why 2nd loop?
> if (ui->peer)
> continue;
> if (!ui->ue->peer)
> @@ -1411,18 +1553,6 @@ static int resolve_unix_peers(void *unused)
> }
>
> ui->peer = peer;
> - if (!peer->queuer)
> - peer->queuer = ui->ue->ino;
> - if (ui == peer)
> - /* socket connected to self %) */
> - continue;
> - if (peer->ue->peer != ui->ue->ino)
> - continue;
> -
> - peer->peer = ui;
> -
> - /* socketpair or interconnected sockets */
> - interconnected_pair(ui, peer);
Plain socketpais() are not not interconnected_pair()-ed, aren't they?
> }
>
> pr_info("Unix sockets:\n");
>
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