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Message-ID: <ZtSjmgk5olK6sfOE@shredder.mtl.com>
Date: Sun, 1 Sep 2024 20:25:46 +0300
From: Ido Schimmel <idosch@...sch.org>
To: Omid Ehtemam-Haghighi <omid.ehtemamhaghighi@...losecurity.com>
Cc: netdev@...r.kernel.org, dsahern@...il.com, edumazet@...gle.com,
adrian.oliver@...losecurity.com
Subject: Re: [PATCH v3] net/ipv6: Fix soft lockups in fib6_select_path under
high next hop churn
Subject prefix should be "[PATCH net]". See:
https://docs.kernel.org/process/maintainer-netdev.html
On Thu, Aug 29, 2024 at 03:28:03PM -0700, Omid Ehtemam-Haghighi wrote:
> Soft lockups have been observed on a cluster of Linux-based edge routers
> located in a highly dynamic environment. Using the `bird` service, these
> routers continuously update BGP-advertised routes due to frequently
> changing nexthop destinations, while also managing significant IPv6
> traffic. The lockups occur during the traversal of the multipath
> circular linked-list in the `fib6_select_path` function, particularly
> while iterating through the siblings in the list. The issue typically
> arises when the nodes of the linked list are unexpectedly deleted
> concurrently on a different core—indicated by their 'next' and
> 'previous' elements pointing back to the node itself and their reference
> count dropping to zero. This results in an infinite loop, leading to a
> soft lockup that triggers a system panic via the watchdog timer.
>
> To fix this issue, I applied RCU primitives in the problematic code
Use imperative mood:
https://docs.kernel.org/process/submitting-patches.html#describe-your-changes
> sections, which successfully resolved the issue within our testing
> parameters and in the production environment where the issue was first
> observed. Additionally, all references to fib6_siblings have been updated
> to annotate or use the RCU APIs.
>
> A test script that reproduces this issue is included with this patch. The
> script periodically updates the routing table while generating a heavy load
> of outgoing IPv6 traffic through multiple iperf3 clients. I have tested
> this script on various machines, ranging from low to high performance, as
> detailed in the comment section of the test script. It consistently induces
> soft lockups within a minute.
>
> Kernel log:
>
> 0 [ffffbd13003e8d30] machine_kexec at ffffffff8ceaf3eb
> 1 [ffffbd13003e8d90] __crash_kexec at ffffffff8d0120e3
> 2 [ffffbd13003e8e58] panic at ffffffff8cef65d4
> 3 [ffffbd13003e8ed8] watchdog_timer_fn at ffffffff8d05cb03
> 4 [ffffbd13003e8f08] __hrtimer_run_queues at ffffffff8cfec62f
> 5 [ffffbd13003e8f70] hrtimer_interrupt at ffffffff8cfed756
> 6 [ffffbd13003e8fd0] __sysvec_apic_timer_interrupt at ffffffff8cea01af
> 7 [ffffbd13003e8ff0] sysvec_apic_timer_interrupt at ffffffff8df1b83d
> -- <IRQ stack> --
> 8 [ffffbd13003d3708] asm_sysvec_apic_timer_interrupt at ffffffff8e000ecb
> [exception RIP: fib6_select_path+299]
> RIP: ffffffff8ddafe7b RSP: ffffbd13003d37b8 RFLAGS: 00000287
> RAX: ffff975850b43600 RBX: ffff975850b40200 RCX: 0000000000000000
> RDX: 000000003fffffff RSI: 0000000051d383e4 RDI: ffff975850b43618
> RBP: ffffbd13003d3800 R8: 0000000000000000 R9: ffff975850b40200
> R10: 0000000000000000 R11: 0000000000000000 R12: ffffbd13003d3830
> R13: ffff975850b436a8 R14: ffff975850b43600 R15: 0000000000000007
> ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
> 9 [ffffbd13003d3808] ip6_pol_route at ffffffff8ddb030c
> 10 [ffffbd13003d3888] ip6_pol_route_input at ffffffff8ddb068c
> 11 [ffffbd13003d3898] fib6_rule_lookup at ffffffff8ddf02b5
> 12 [ffffbd13003d3928] ip6_route_input at ffffffff8ddb0f47
> 13 [ffffbd13003d3a18] ip6_rcv_finish_core.constprop.0 at ffffffff8dd950d0
> 14 [ffffbd13003d3a30] ip6_list_rcv_finish.constprop.0 at ffffffff8dd96274
> 15 [ffffbd13003d3a98] ip6_sublist_rcv at ffffffff8dd96474
> 16 [ffffbd13003d3af8] ipv6_list_rcv at ffffffff8dd96615
> 17 [ffffbd13003d3b60] __netif_receive_skb_list_core at ffffffff8dc16fec
> 18 [ffffbd13003d3be0] netif_receive_skb_list_internal at ffffffff8dc176b3
> 19 [ffffbd13003d3c50] napi_gro_receive at ffffffff8dc565b9
> 20 [ffffbd13003d3c80] ice_receive_skb at ffffffffc087e4f5 [ice]
> 21 [ffffbd13003d3c90] ice_clean_rx_irq at ffffffffc0881b80 [ice]
> 22 [ffffbd13003d3d20] ice_napi_poll at ffffffffc088232f [ice]
> 23 [ffffbd13003d3d80] __napi_poll at ffffffff8dc18000
> 24 [ffffbd13003d3db8] net_rx_action at ffffffff8dc18581
> 25 [ffffbd13003d3e40] __do_softirq at ffffffff8df352e9
> 26 [ffffbd13003d3eb0] run_ksoftirqd at ffffffff8ceffe47
> 27 [ffffbd13003d3ec0] smpboot_thread_fn at ffffffff8cf36a30
> 28 [ffffbd13003d3ee8] kthread at ffffffff8cf2b39f
> 29 [ffffbd13003d3f28] ret_from_fork at ffffffff8ce5fa64
> 30 [ffffbd13003d3f50] ret_from_fork_asm at ffffffff8ce03cbb
>
> Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)")
Would be more appropriate to blame commit 66f5d6ce53e6 ("ipv6: replace
rwlock with rcu and spinlock in fib6_table"). Before this commit readers
could not traverse the siblings list in the data path while writers
modified it in the control path.
> Reported-by: Omid Ehtemam-Haghighi <omid.ehtemamhaghighi@...losecurity.com>
> Tested-by: Omid Ehtemam-Haghighi <omid.ehtemamhaghighi@...losecurity.com>
> Signed-off-by: Omid Ehtemam-Haghighi <omid.ehtemamhaghighi@...losecurity.com>
> Cc: David Ahern <dsahern@...il.com>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Ido Schimmel <idosch@...sch.org>
> ---
> v2 -> v3:
> * Removed redundant rcu_read_lock()/rcu_read_unlock() pairs
> * Revised the test script based on Ido Schimmel's feedback
> * Updated the test script to ensure compatibility with the latest iperf3 version
> * Fixed new warnings generated with 'C=2' in the previous version
> * Other review comments addressed
>
> v1 -> v2:
> * list_del_rcu() is applied exclusively to legacy multipath code
> * All occurrences of fib6_siblings have been modified to utilize RCU
> APIs for annotation and usage.
> * Additionally, a test script for reproducing the reported
> issue is included
> ---
> net/ipv6/ip6_fib.c | 22 +-
> net/ipv6/route.c | 30 ++-
> tools/testing/selftests/net/Makefile | 1 +
> .../net/ipv6_route_update_soft_lockup.sh | 226 ++++++++++++++++++
> 4 files changed, 261 insertions(+), 18 deletions(-)
> create mode 100755 tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh
>
> diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
> index eb111d20615c..002cddc5d3b5 100644
> --- a/net/ipv6/ip6_fib.c
> +++ b/net/ipv6/ip6_fib.c
> @@ -518,7 +518,7 @@ int fib6_tables_dump(struct net *net, struct notifier_block *nb,
> static int fib6_dump_node(struct fib6_walker *w)
> {
> int res;
> - struct fib6_info *rt;
> + struct fib6_info *rt, *sibling, *last_sibling;
>
> for_each_fib6_walker_rt(w) {
> res = rt6_dump_route(rt, w->args, w->skip_in_node);
> @@ -540,10 +540,14 @@ static int fib6_dump_node(struct fib6_walker *w)
> * last sibling of this route (no need to dump the
> * sibling routes again)
> */
> - if (rt->fib6_nsiblings)
> - rt = list_last_entry(&rt->fib6_siblings,
> - struct fib6_info,
> - fib6_siblings);
> + if (rt->fib6_nsiblings) {
> + last_sibling = rt;
> + list_for_each_entry_rcu(sibling, &rt->fib6_siblings,
> + fib6_siblings)
> + last_sibling = sibling;
> +
> + rt = last_sibling;
> + }
> }
> w->leaf = NULL;
> return 0;
Are you sure this hunk is needed? Seems this function is always called
with the table lock held.
> @@ -1190,8 +1194,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
> while (sibling) {
> if (sibling->fib6_metric == rt->fib6_metric &&
> rt6_qualify_for_ecmp(sibling)) {
> - list_add_tail(&rt->fib6_siblings,
> - &sibling->fib6_siblings);
> + list_add_tail_rcu(&rt->fib6_siblings,
> + &sibling->fib6_siblings);
> break;
> }
> sibling = rcu_dereference_protected(sibling->fib6_next,
> @@ -1252,7 +1256,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
> fib6_siblings)
> sibling->fib6_nsiblings--;
> rt->fib6_nsiblings = 0;
> - list_del_init(&rt->fib6_siblings);
> + list_del_rcu(&rt->fib6_siblings);
> rt6_multipath_rebalance(next_sibling);
> return err;
> }
> @@ -1970,7 +1974,7 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
> &rt->fib6_siblings, fib6_siblings)
> sibling->fib6_nsiblings--;
> rt->fib6_nsiblings = 0;
> - list_del_init(&rt->fib6_siblings);
> + list_del_rcu(&rt->fib6_siblings);
> rt6_multipath_rebalance(next_sibling);
> }
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 219701caba1e..12dc1acb6463 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -413,7 +413,7 @@ void fib6_select_path(const struct net *net, struct fib6_result *res,
> struct flowi6 *fl6, int oif, bool have_oif_match,
> const struct sk_buff *skb, int strict)
> {
> - struct fib6_info *sibling, *next_sibling;
> + struct fib6_info *sibling;
> struct fib6_info *match = res->f6i;
>
> if (!match->nh && (!match->fib6_nsiblings || have_oif_match))
> @@ -440,8 +440,10 @@ void fib6_select_path(const struct net *net, struct fib6_result *res,
> if (fl6->mp_hash <= atomic_read(&match->fib6_nh->fib_nh_upper_bound))
> goto out;
>
> - list_for_each_entry_safe(sibling, next_sibling, &match->fib6_siblings,
> - fib6_siblings) {
> + rcu_read_lock();
fib6_select_path() should already be called with rcu_read_lock()
> +
> + list_for_each_entry_rcu(sibling, &match->fib6_siblings,
> + fib6_siblings) {
> const struct fib6_nh *nh = sibling->fib6_nh;
> int nh_upper_bound;
>
> @@ -454,6 +456,8 @@ void fib6_select_path(const struct net *net, struct fib6_result *res,
> break;
> }
>
> + rcu_read_unlock();
> +
> out:
> res->f6i = match;
> res->nh = match->fib6_nh;
> @@ -5195,14 +5199,18 @@ static void ip6_route_mpath_notify(struct fib6_info *rt,
> * nexthop. Since sibling routes are always added at the end of
> * the list, find the first sibling of the last route appended
> */
> + rcu_read_lock();
> +
> if ((nlflags & NLM_F_APPEND) && rt_last && rt_last->fib6_nsiblings) {
> - rt = list_first_entry(&rt_last->fib6_siblings,
> - struct fib6_info,
> - fib6_siblings);
> + rt = list_first_or_null_rcu(&rt_last->fib6_siblings,
> + struct fib6_info,
> + fib6_siblings);
> }
>
> if (rt)
> inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
> +
> + rcu_read_unlock();
> }
>
> static bool ip6_route_mpath_should_notify(const struct fib6_info *rt)
> @@ -5547,17 +5555,21 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i)
> nexthop_for_each_fib6_nh(f6i->nh, rt6_nh_nlmsg_size,
> &nexthop_len);
> } else {
> - struct fib6_info *sibling, *next_sibling;
> + struct fib6_info *sibling;
> struct fib6_nh *nh = f6i->fib6_nh;
>
> nexthop_len = 0;
> if (f6i->fib6_nsiblings) {
> rt6_nh_nlmsg_size(nh, &nexthop_len);
>
> - list_for_each_entry_safe(sibling, next_sibling,
> - &f6i->fib6_siblings, fib6_siblings) {
> + rcu_read_lock();
> +
> + list_for_each_entry_rcu(sibling, &f6i->fib6_siblings,
> + fib6_siblings) {
> rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len);
> }
> +
> + rcu_read_unlock();
> }
> nexthop_len += lwtunnel_get_encap_size(nh->fib_nh_lws);
> }
What about rt6_fill_node() ? It's not always called with the table lock
held
> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
> index 8eaffd7a641c..95e5e5cd1195 100644
> --- a/tools/testing/selftests/net/Makefile
> +++ b/tools/testing/selftests/net/Makefile
> @@ -94,6 +94,7 @@ TEST_PROGS += fdb_flush.sh
> TEST_PROGS += fq_band_pktlimit.sh
> TEST_PROGS += vlan_hw_filter.sh
> TEST_PROGS += bpf_offload.py
> +TEST_PROGS += ipv6_route_update_soft_lockup.sh
>
> TEST_FILES := settings
> TEST_FILES += in_netns.sh lib.sh net_helper.sh setup_loopback.sh setup_veth.sh
> diff --git a/tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh b/tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh
> new file mode 100755
> index 000000000000..f55488e4645c
> --- /dev/null
> +++ b/tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh
> @@ -0,0 +1,226 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Testing for potential kernel soft lockup during IPv6 routing table
> +# refresh under heavy outgoing IPv6 traffic. If a kernel soft lockup
> +# occurs, a kernel panic will be triggered to prevent associated issues.
> +#
> +#
> +# Test Environment Layout
> +#
> +# ┌-----------------┐ ┌------------------┐
> +# | SOURCE_NS | | SINK_NS |
> +# | NAMESPACE | | NAMESPACE |
> +# |(iperf3 clients) | | (iperf3 servers) |
> +# | | | |
> +# | | | |
> +# | ┌-----------| nexthops |---------┐ |
> +# | |veth_source|<------------------------------------------->|veth_sink|<-┐ |
> +# | └-----------| 2001:0DB8:1::0:1/96 2001:0DB8:1::1:1/96 |---------┘ | |
> +# | | ^ 2001:0DB8:1::1:2/96 | | |
> +# | | . . | | fwd |
> +# | ┌---------┐ | . . | | |
> +# | | IPv6 | | . . | V |
> +# | | routing | | . 2001:0DB8:1::1:80/96| ┌-----┐ |
> +# | | table | | . | | lo | |
> +# | | nexthop | | . └---------┴-----┴--┘
> +# | | update | | ..................................> 2001:0DB8:2::1:1/128
> +# | └-------- ┘ |
> +# └-----------------┘
> +#
> +# The test script sets up two network namespaces, source_ns and sink_ns,
> +# connected via a veth link. Within source_ns, it continuously updates the
> +# IPv6 routing table by flushing and inserting IPV6_NEXTHOP_ADDR_COUNT nexthop
> +# IPs destined for SINK_LOOPBACK_IP_ADDR in sink_ns. This refresh occurs at a
> +# rate of 1/ROUTING_TABLE_REFRESH_PERIOD per second for TEST_DURATION seconds.
> +#
> +# Simultaneously, multiple iperf3 clients within source_ns generate heavy
> +# outgoing IPv6 traffic. Each client is assigned a unique port number starting
> +# at 5000 and incrementing sequentially. Each client targets a unique iperf3
> +# server running in sink_ns, connected to the SINK_LOOPBACK_IFACE interface
> +# using the same port number.
> +#
> +# The number of iperf3 servers and clients is set to half of the total
> +# available cores on each machine.
> +#
> +# NOTE: We have tested this script on machines with various CPU specifications,
> +# ranging from lower to higher performance as listed below. The test script
> +# effectively triggered a kernel soft lockup on machines running an unpatched
> +# kernel in under a minute:
> +#
> +# - 1x Intel Xeon E-2278G 8-Core Processor @ 3.40GHz
> +# - 1x Intel Xeon E-2378G Processor 8-Core @ 2.80GHz
> +# - 1x AMD EPYC 7401P 24-Core Processor @ 2.00GHz
> +# - 1x AMD EPYC 7402P 24-Core Processor @ 2.80GHz
> +# - 2x Intel Xeon Gold 5120 14-Core Processor @ 2.20GHz
> +# - 1x Ampere Altra Q80-30 80-Core Processor @ 3.00GHz
> +# - 2x Intel Xeon Gold 5120 14-Core Processor @ 2.20GHz
> +# - 2x Intel Xeon Silver 4214 24-Core Processor @ 2.20GHz
> +# - 1x AMD EPYC 7502P 32-Core @ 2.50GHz
> +# - 1x Intel Xeon Gold 6314U 32-Core Processor @ 2.30GHz
> +# - 2x Intel Xeon Gold 6338 32-Core Processor @ 2.00GHz
> +#
> +# On less performant machines, you may need to increase the TEST_DURATION
> +# parameter to enhance the likelihood of encountering a race condition leading
> +# to a kernel soft lockup and avoid a false negative result.
> +
> +source lib.sh
> +
> +TEST_DURATION=120
> +ROUTING_TABLE_REFRESH_PERIOD=0.01
> +
> +IPERF3_BITRATE="300m"
> +
> +
> +IPV6_NEXTHOP_ADDR_COUNT="128"
> +IPV6_NEXTHOP_ADDR_MASK="96"
> +IPV6_NEXTHOP_PREFIX="2001:0DB8:1"
> +
> +
> +SOURCE_TEST_IFACE="veth_source"
> +SOURCE_TEST_IP_ADDR="2001:0DB8:1::0:1/96"
> +
> +SINK_TEST_IFACE="veth_sink"
> +# ${SINK_TEST_IFACE} is populated with the following range of IPv6 addresses:
> +# 2001:0DB8:1::1:1 to 2001:0DB8:1::1:${IPV6_NEXTHOP_ADDR_COUNT}
> +SINK_LOOPBACK_IFACE="lo"
> +SINK_LOOPBACK_IP_MASK="128"
> +SINK_LOOPBACK_IP_ADDR="2001:0DB8:2::1:1"
> +
> +nexthop_ip_list=""
> +termination_signal=""
> +kernel_softlokup_panic_prev_val=""
> +
> +cleanup() {
> + echo "info: cleaning up namespaces and terminating all processes within them..."
> +
> + kill -9 $(pgrep -f "iperf3") > /dev/null 2>&1
> + sleep 1
> + kill -9 $(pgrep -f "ip netns list | grep -q ${source_ns}") > /dev/null 2>&1
> + sleep 1
> +
> + # Check if any iperf3 instances are still running. This could occur if a core has entered an infinite loop and
> + # the timeout for the soft lockup to be detected has not expired yet, but either the test interval has already
> + # elapsed or the test is terminated manually (Ctrl+C)
> + if pgrep -f "iperf3" > /dev/null; then
> + echo "FAIL: unable to terminate some iperf3 instances. Soft lockup is underway. A kernel panic is on the way!"
> + exit ${ksft_fail}
> + else
> + if [ "$termination_signal" == "SIGINT" ]; then
> + echo "SKIP: Termination due to ^C (SIGINT)"
> + elif [ "$termination_signal" == "SIGALRM" ]; then
> + echo "PASS: No kernel soft lockup occurred during this ${TEST_DURATION} second test"
> + fi
> + fi
> +
> + cleanup_ns ${source_ns} ${sink_ns}
> +
> + sysctl -qw kernel.softlockup_panic=${kernel_softlokup_panic_prev_val}
> +}
> +
> +setup_prepare() {
> + setup_ns source_ns sink_ns
> +
> + ip -n ${source_ns} link add name ${SOURCE_TEST_IFACE} type veth peer name ${SINK_TEST_IFACE} netns ${sink_ns}
> +
> + # Setting up the Source namespace
> + ip -n ${source_ns} addr add ${SOURCE_TEST_IP_ADDR} dev ${SOURCE_TEST_IFACE}
> + ip -n ${source_ns} link set dev ${SOURCE_TEST_IFACE} qlen 10000
> + ip -n ${source_ns} link set dev ${SOURCE_TEST_IFACE} up
> + ip netns exec ${source_ns} sysctl -qw net.ipv6.fib_multipath_hash_policy=1
> +
> + # Setting up the Sink namespace
> + ip -n ${sink_ns} addr add ${SINK_LOOPBACK_IP_ADDR}/${SINK_LOOPBACK_IP_MASK} dev ${SINK_LOOPBACK_IFACE}
> + ip -n ${sink_ns} link set dev ${SINK_LOOPBACK_IFACE} up
> + ip netns exec ${sink_ns} sysctl -qw net.ipv6.conf.${SINK_LOOPBACK_IFACE}.forwarding=1
> +
> + ip -n ${sink_ns} link set ${SINK_TEST_IFACE} up
> + ip netns exec ${sink_ns} sysctl -qw net.ipv6.conf.${SINK_TEST_IFACE}.forwarding=1
> +
> +
> + # Populating Nexthop IPv6 addresses on the test interface of the sink_ns namespace
> + echo "info: populating ${IPV6_NEXTHOP_ADDR_COUNT} IPv6 addresses on the ${SINK_TEST_IFACE} interface ..."
> + for IP in $(seq 1 ${IPV6_NEXTHOP_ADDR_COUNT}); do
> + ip -n ${sink_ns} addr add ${IPV6_NEXTHOP_PREFIX}::$(printf "1:%x" "${IP}")/${IPV6_NEXTHOP_ADDR_MASK} dev ${SINK_TEST_IFACE};
> + done
> +
> + # Preparing list of nexthops
> + for IP in $(seq 1 ${IPV6_NEXTHOP_ADDR_COUNT}); do
> + nexthop_ip_list=$nexthop_ip_list" nexthop via ${IPV6_NEXTHOP_PREFIX}::$(printf "1:%x" $IP) dev ${SOURCE_TEST_IFACE} weight 1"
> + done
> +}
> +
> +
> +test_soft_lockup_during_routing_table_refresh() {
> + # Start num_of_iperf_servers iperf3 servers in the sink_ns namespace, each listening on ports
> + # starting at 5001 and incrementing sequentially.
> + echo "info: starting ${num_of_iperf_servers} iperf3 servers in the sink_ns namespace ..."
> + for i in $(seq 1 ${num_of_iperf_servers}); do
> + cmd="iperf3 --bind ${SINK_LOOPBACK_IP_ADDR} -s -p $(printf '5%03d' ${i}) > /dev/null 2>&1"
> + ip netns exec ${sink_ns} bash -c "while true; do ${cmd}; done &"
> + done
> +
> + # Wait for a while for the iperf3 servers to become ready
> + sleep 2
> +
> + # Continuously refresh the routing table in background in the Source namespase
> + ip netns exec ${source_ns} bash -c "
> + while \$(ip netns list | grep -q ${source_ns}); do
> + ip -6 route add ${SINK_LOOPBACK_IP_ADDR}/${SINK_LOOPBACK_IP_MASK} ${nexthop_ip_list};
> + sleep ${ROUTING_TABLE_REFRESH_PERIOD};
> + ip -6 route delete ${SINK_LOOPBACK_IP_ADDR}/${SINK_LOOPBACK_IP_MASK};
> + done &"
> +
> + # Start num_of_iperf_servers iperf3 clients in the source_ns namespace, each sending TCP traffic on sequential ports starting at 5001
> + echo "info: starting ${num_of_iperf_servers} iperf3 clients in the source_ns namespace ..."
> + for i in $(seq 1 ${num_of_iperf_servers}); do
> + cmd="iperf3 -c ${SINK_LOOPBACK_IP_ADDR} -p $(printf '5%03d' ${i}) --length 64 --bitrate ${IPERF3_BITRATE} -t 0 > /dev/null 2>&1"
> + ip netns exec ${source_ns} bash -c "while true; do ${cmd}; done &"
> + done
> +
> + echo "info: IPv6 routing table is being updated at the rate of $(echo "1/${ROUTING_TABLE_REFRESH_PERIOD}" | bc)/s for ${TEST_DURATION} seconds ..."
> + echo "info: A kernel soft lockup, if detected, results in a kernel panic!"
> +
> + wait
> +}
> +
> +# Make sure 'iperf3' is installed, skip the test otherwise
> +if [ ! -x "$(command -v "iperf3")" ]; then
> + echo "SKIP: 'iperf3' is not installed. Skipping the test."
> + exit ${ksft_skip}
> +fi
> +
> +# Determine the number of cores on the machine
> +num_of_iperf_servers=$(( $(nproc)/2 ))
> +
> +# Check if we are running on a multi-core machine, skip the test otherwise
> +if [ "${num_of_iperf_servers}" -eq 0 ]; then
> + echo "SKIP: This test is not valid on a single core machine!"
> + exit ${ksft_skip}
> +fi
> +
> +# Since the kernel soft lockup we're testing against causes at least one core
> +# to enter an infinite loop, making the host unstable and likely affecting
> +# subsequent tests, we trigger a kernel panic instead of reporting a failure.
> +kernel_softlokup_panic_prev_val=$(sysctl -n kernel.softlockup_panic)
> +sysctl -qw kernel.softlockup_panic=1
> +
> +handle_sigint() {
> + termination_signal="SIGINT"
> + cleanup
> + exit ${ksft_skip}
> +}
> +
> +handle_sigalrm() {
> + termination_signal="SIGALRM"
> + cleanup
> + exit ${ksft_pass}
> +}
> +
> +trap handle_sigint SIGINT
> +trap handle_sigalrm SIGALRM
> +
> +(sleep ${TEST_DURATION} && kill -s SIGALRM $$)&
> +
> +setup_prepare
> +test_soft_lockup_during_routing_table_refresh
> --
> 2.43.0
>
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