[pve-devel] [PATCH kronosnet 1/2] fix #3672: cherry-pick knet fixes

Fabian Grünbichler f.gruenbichler at proxmox.com
Tue Nov 9 13:07:41 CET 2021


see https://github.com/corosync/corosync/issues/660 as well. these are
already queued for 1.23 and taken straight from stable1-proposed.

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---
 ...eq_num-initialization-race-condition.patch | 53 +++++++++++
 ...or-messages-to-trigger-faster-link-d.patch | 92 +++++++++++++++++++
 debian/patches/series                         |  3 +-
 3 files changed, 147 insertions(+), 1 deletion(-)
 create mode 100644 debian/patches/0001-host-fix-dst_seq_num-initialization-race-condition.patch
 create mode 100644 debian/patches/0002-udp-use-ICMP-error-messages-to-trigger-faster-link-d.patch

diff --git a/debian/patches/0001-host-fix-dst_seq_num-initialization-race-condition.patch b/debian/patches/0001-host-fix-dst_seq_num-initialization-race-condition.patch
new file mode 100644
index 0000000..d01e0d4
--- /dev/null
+++ b/debian/patches/0001-host-fix-dst_seq_num-initialization-race-condition.patch
@@ -0,0 +1,53 @@
+From 7eebe93c5039dad432bdd40101287e7fc04b3d10 Mon Sep 17 00:00:00 2001
+From: "Fabio M. Di Nitto" <fdinitto at redhat.com>
+Date: Mon, 8 Nov 2021 09:14:22 +0100
+Subject: [PATCH 1/2] [host] fix dst_seq_num initialization race condition
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+There is a potential race condition where the sender
+is overloaded, sending data packets before pings
+can kick in and set the correct dst_seq_num.
+
+if this node is starting up (dst_seq_num = 0),
+it can start rejecing valid packets and get stuck.
+
+Set the dst_seq_num to the first seen packet and
+use that as reference instead.
+
+Signed-off-by: Fabio M. Di Nitto <fdinitto at redhat.com>
+Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
+---
+ libknet/host.c | 15 +++++++++++++++
+ 1 file changed, 15 insertions(+)
+
+diff --git a/libknet/host.c b/libknet/host.c
+index ec73c0df..6fca01f8 100644
+--- a/libknet/host.c
++++ b/libknet/host.c
+@@ -573,6 +573,21 @@ int _seq_num_lookup(struct knet_host *host, seq_num_t seq_num, int defrag_buf, i
+ 	char *dst_cbuf_defrag = host->circular_buffer_defrag;
+ 	seq_num_t *dst_seq_num = &host->rx_seq_num;
+ 
++	/*
++	 * There is a potential race condition where the sender
++	 * is overloaded, sending data packets before pings
++	 * can kick in and set the correct dst_seq_num.
++	 *
++	 * if this node is starting up (dst_seq_num = 0),
++	 * it can start rejecing valid packets and get stuck.
++	 *
++	 * Set the dst_seq_num to the first seen packet and
++	 * use that as reference instead.
++	 */
++	if (!*dst_seq_num) {
++		*dst_seq_num = seq_num;
++	}
++
+ 	if (clear_buf) {
+ 		_clear_cbuffers(host, seq_num);
+ 	}
+-- 
+2.30.2
+
diff --git a/debian/patches/0002-udp-use-ICMP-error-messages-to-trigger-faster-link-d.patch b/debian/patches/0002-udp-use-ICMP-error-messages-to-trigger-faster-link-d.patch
new file mode 100644
index 0000000..c8a9990
--- /dev/null
+++ b/debian/patches/0002-udp-use-ICMP-error-messages-to-trigger-faster-link-d.patch
@@ -0,0 +1,92 @@
+From 1d52003ae7814ebf2b47c1ac3463c7d82486a5fd Mon Sep 17 00:00:00 2001
+From: "Fabio M. Di Nitto" <fdinitto at redhat.com>
+Date: Sun, 7 Nov 2021 17:02:05 +0100
+Subject: [PATCH 2/2] [udp] use ICMP error messages to trigger faster link down
+ detection
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+this solves a possible race condition when:
+
+- node1 is running
+- node2 very fast
+- node1 does NOT have enough time to detect that node2 has gone
+  and reset the local seq numbers / buffers
+- node1 will start rejecting valid packets from node2
+
+There is still a potential minor race condition where app
+can restart so fast that kernel / network don't have time
+to generate an ICMP error. This will be addressed using
+instance id in onwire v2 protocol, as suggested by Jan F.
+
+Signed-off-by: Fabio M. Di Nitto <fdinitto at redhat.com>
+Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
+---
+ libknet/transport_udp.c | 44 +++++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 44 insertions(+)
+
+diff --git a/libknet/transport_udp.c b/libknet/transport_udp.c
+index 482c99b1..a1419c89 100644
+--- a/libknet/transport_udp.c
++++ b/libknet/transport_udp.c
+@@ -364,6 +364,46 @@ static int read_errs_from_sock(knet_handle_t knet_h, int sockfd)
+ 									log_debug(knet_h, KNET_SUB_TRANSP_UDP, "Received ICMP error from %s: %s destination unknown", addr_str, strerror(sock_err->ee_errno));
+ 								} else {
+ 									log_debug(knet_h, KNET_SUB_TRANSP_UDP, "Received ICMP error from %s: %s %s", addr_str, strerror(sock_err->ee_errno), addr_remote_str);
++									if ((sock_err->ee_errno == ECONNREFUSED) || /* knet is not running on the other node */
++									    (sock_err->ee_errno == ECONNABORTED) || /* local kernel closed the socket */
++									    (sock_err->ee_errno == ENONET)       || /* network does not exist */
++									    (sock_err->ee_errno == ENETUNREACH)  || /* network unreachable */
++									    (sock_err->ee_errno == EHOSTUNREACH) || /* host unreachable */
++									    (sock_err->ee_errno == EHOSTDOWN)    || /* host down (from kernel/net/ipv4/icmp.c */
++									    (sock_err->ee_errno == ENETDOWN)) {     /* network down */
++										struct knet_host *host = NULL;
++										struct knet_link *kn_link = NULL;
++										int link_idx, found = 0;
++
++										for (host = knet_h->host_head; host != NULL; host = host->next) {
++											for (link_idx = 0; link_idx < KNET_MAX_LINK; link_idx++) {
++												kn_link = &host->link[link_idx];
++												if (kn_link->outsock == sockfd) {
++													if (!cmpaddr(&remote, &kn_link->dst_addr)) {
++														found = 1;
++														break;
++													}
++												}
++											}
++											if (found) {
++												break;
++											}
++										}
++
++										if ((host) && (kn_link) &&
++										    (kn_link->status.connected)) {
++											log_debug(knet_h, KNET_SUB_TRANSP_UDP, "Setting down host %u link %i", host->host_id, kn_link->link_id);
++											/*
++											 * setting transport_connected = 0 will trigger
++											 * thread_heartbeat link_down process.
++											 *
++											 * the process terminates calling into transport_link_down
++											 * below that will set transport_connected = 1
++											 */
++											kn_link->transport_connected = 0;
++										}
++
++									}
+ 								}
+ 							}
+ 							break;
+@@ -436,5 +476,9 @@ int udp_transport_link_dyn_connect(knet_handle_t knet_h, int sockfd, struct knet
+ 
+ int udp_transport_link_is_down(knet_handle_t knet_h, struct knet_link *kn_link)
+ {
++	/*
++	 * see comments about handling ICMP error messages
++	 */
++	kn_link->transport_connected = 1;
+ 	return 0;
+ }
+-- 
+2.30.2
+
diff --git a/debian/patches/series b/debian/patches/series
index 8b13789..16fba19 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1 +1,2 @@
-
+0001-host-fix-dst_seq_num-initialization-race-condition.patch
+0002-udp-use-ICMP-error-messages-to-trigger-faster-link-d.patch
-- 
2.30.2





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