On 2019-07-18 17:46:55 [-0300], Luis Claudio R. Goncalves wrote: > Hello, > > Sounds like ptp_classify_raw() should be reached with IRQs disabled to > safely call BPF_PROG_RUN(). I am just unsure where, down the road, the > proper context should have been set. > > 08:46:58 darkmatter kernel: BUG: assuming atomic context at net/core/ptp_classifier.c:106 > Jul 17 08:46:58 darkmatter kernel: in_atomic(): 0, irqs_disabled(): 0, pid: 1129, name: irq/35-enp4s0 > Jul 17 08:46:58 darkmatter kernel: CPU: 1 PID: 1129 Comm: irq/35-enp4s0 Not tainted 5.2.0-rt1 #1 > Jul 17 08:46:58 darkmatter kernel: Hardware name: Hewlett-Packard p7-1512/2ADA, BIOS 8.15 02/05/2013 > Jul 17 08:46:58 darkmatter kernel: Call Trace: > Jul 17 08:46:58 darkmatter kernel: dump_stack+0x67/0x90 > Jul 17 08:46:58 darkmatter kernel: __cant_sleep.cold+0x68/0x74 > Jul 17 08:46:58 darkmatter kernel: ptp_classify_raw+0x1f/0xa0 > Jul 17 08:46:58 darkmatter kernel: skb_defer_rx_timestamp+0x5a/0xb0 > Jul 17 08:46:58 darkmatter kernel: netif_receive_skb_internal+0x34/0xe0 > Jul 17 08:46:58 darkmatter kernel: napi_gro_receive+0x66/0x1c0 > Jul 17 08:46:58 darkmatter kernel: rtl8169_poll+0x216/0x610 [r8169] > Jul 17 08:46:58 darkmatter kernel: net_rx_action+0x208/0x490 > Jul 17 08:46:58 darkmatter kernel: __do_softirq+0x140/0x3c9 > Jul 17 08:46:58 darkmatter kernel: __local_bh_enable_ip+0x13d/0x160 > Jul 17 08:46:58 darkmatter kernel: irq_forced_thread_fn+0x70/0x80 > Jul 17 08:46:58 darkmatter kernel: irq_thread+0xf6/0x1d0 > Jul 17 08:46:58 darkmatter kernel: kthread+0x103/0x140 > Jul 17 08:46:58 darkmatter kernel: ret_from_fork+0x3a/0x50 > Jul 17 08:46:58 darkmatter kernel: bpfilter: Loaded bpfilter_umh pid 1160 > Jul 17 08:46:58 darkmatter kernel: bpfilter: read fail -13 I would argue that this cant_sleep() thingy is nonsense. On !RT you run in softirq and while this check does not trigger (because the preemption counter is != 0) you can be preempted by an IRQ. I have no idea what it intends to protect. The commit does not explain why it is important to keep preemption disabled while invoking a BPF program. > Luis Sebastian
