3f0d14efe2
When dereferencing the port vlan group we should use the rcu helper instead of the one relying on rtnl. In br_multicast_pg_to_port_ctx the entry cannot disappear as we hold the multicast lock and rcu as explained in the comment above it. For the same reason we're ok in br_multicast_start_querier. ============================= WARNING: suspicious RCU usage 5.14.0-rc5+ #429 Tainted: G W ----------------------------- net/bridge/br_private.h:1478 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by swapper/2/0: #0: ffff88822be85eb0 ((&p->timer)){+.-.}-{0:0}, at: call_timer_fn+0x5/0x2da #1: ffff88810b32f260 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_group_expired+0x28/0x13d [bridge] #2: ffffffff824f6c80 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire.constprop.0+0x0/0x22 [bridge] stack backtrace: CPU: 2 PID: 0 Comm: swapper/2 Kdump: loaded Tainted: G W 5.14.0-rc5+ #429 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014 Call Trace: <IRQ> dump_stack_lvl+0x45/0x59 nbp_vlan_group+0x3e/0x44 [bridge] br_multicast_pg_to_port_ctx+0xd6/0x10d [bridge] br_multicast_star_g_handle_mode+0xa1/0x2ce [bridge] ? netlink_broadcast+0xf/0x11 ? nlmsg_notify+0x56/0x99 ? br_mdb_notify+0x224/0x2e9 [bridge] ? br_multicast_del_pg+0x1dc/0x26d [bridge] br_multicast_del_pg+0x1dc/0x26d [bridge] br_multicast_port_group_expired+0xaa/0x13d [bridge] ? __grp_src_delete_marked.isra.0+0x35/0x35 [bridge] ? __grp_src_delete_marked.isra.0+0x35/0x35 [bridge] call_timer_fn+0x134/0x2da __run_timers+0x169/0x193 run_timer_softirq+0x19/0x2d __do_softirq+0x1bc/0x42a __irq_exit_rcu+0x5c/0xb3 irq_exit_rcu+0xa/0x12 sysvec_apic_timer_interrupt+0x5e/0x75 </IRQ> asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:default_idle+0xc/0xd Code: e8 14 40 71 ff e8 10 b3 ff ff 4c 89 e2 48 89 ef 31 f6 5d 41 5c e9 a9 e8 c2 ff cc cc cc cc 0f 1f 44 00 00 e8 7f 55 65 ff fb f4 <c3> 0f 1f 44 00 00 55 65 48 8b 2c 25 40 6f 01 00 53 f0 80 4d 02 20 RSP: 0018:ffff88810033bf00 EFLAGS: 00000206 RAX: ffffffff819cf828 RBX: ffff888100328000 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff819cfa2d RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 R10: ffff8881008302c0 R11: 00000000000006db R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 ? __sched_text_end+0x4/0x4 ? default_idle_call+0x15/0x7b default_idle_call+0x4d/0x7b do_idle+0x124/0x2a2 cpu_startup_entry+0x1d/0x1f secondary_startup_64_no_verify+0xb0/0xbb Fixes: 74edfd483de8 ("net: bridge: multicast: add helper to get port mcast context from port group") Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.