PACKET socket can retain its fanout membership through link down and up and leave a fanout while closed regardless of link state. However, socket was forbidden from joining a fanout while it was not RUNNING. This scenario was identified while studying DPDK pmd_af_packet_drv. Since sockets are only created during initialization, there is no reason to fail the initialization if a single link is temporarily down. This patch allows PACKET socket to join a fanout while not RUNNING. Selftest psock_fanout is extended to test this "fanout while link down" scenario. Selftest psock_fanout is also extended to test fanout create/join by socket that did not bind or specified a protocol, which carries an implicit bind. This is the only test that was performed. Changes: V04: * Minimized code change. * Removed test of ifindex. A socket that went through bind "unlisted" race can join a fanout. V03: https://lore.kernel.org/netdev/cover.1728555449.git.gur.stavi@xxxxxxxxxx * psock_fanout: add test for joining fanout with unbound socket. * Test that socket can receive packets before adding it to a fanout match. This is kind of replaces the RUNNING test that was removed. * Initialize po->ifindex in packet_create. To -1 if no protocol is specified and add an explicit initialization to 0 if protocol is specified. * Refactor relevant code in fanout_add within bind_lock, as a sequence of if {} else if {}, in order to reduce indentation of nested if statements and provide specific error codes. V02: https://lore.kernel.org/netdev/cover.1728382839.git.gur.stavi@xxxxxxxxxx * psock_fanout: use explicit loopback up/down instead of toggle. * psock_fanout: don't try to restore loopback state on failure. * Rephrase commit message about "leaving a fanout". V01: https://lore.kernel.org/netdev/cover.1728303615.git.gur.stavi@xxxxxxxxxx/ Gur Stavi (3): af_packet: allow fanout_add when socket is not RUNNING selftests: net/psock_fanout: socket joins fanout when link is down selftests: net/psock_fanout: unbound socket fanout net/packet/af_packet.c | 9 +-- tools/testing/selftests/net/psock_fanout.c | 78 +++++++++++++++++++++- 2 files changed, 80 insertions(+), 7 deletions(-) base-commit: c531f2269a53db5cf64b24baf785ccbcda52970f -- 2.45.2
