On 04/09/2020 10:52 AM, Dirk Behme wrote:
> Analyzing [1] it seems there is a race condition where ravb_start_xmit()
> can be called from interrupt while tx skbuffs are being torn down in
> the scheduled timeout handling. The actual timeout work is done in
> ravb_tx_timeout_work() during which the tx skbuffs are torn down via
> invocations of ravb_ring_free(). But there seems to be no flag to tell
> the driver it is shutting down so it continues to use the ring buffer
> when it should not.
>
> Fix this by disabling the interrupts in the timeout handler.
>
> [1]
>
> -- cut --
> ravb e6800000.ethernet ethernet: transmit timed out, status 00000000, resetting...
> ravb e6800000.ethernet ethernet: failed to switch device to config mode
> Unable to handle kernel NULL pointer dereference at virtual address 00000018
> Mem abort info:
> Exception class = DABT (current EL), IL = 32 bits
> SET = 0, FnV = 0
> EA = 0, S1PTW = 0
> Data abort info:
> ISV = 0, ISS = 0x00000046
> CM = 0, WnR = 1
> user pgtable: 4k pages, 48-bit VAs, pgd = ffff80065622f000
> [0000000000000018] *pgd=00000006962a7003
> , *pud=00000006962a8003
> , *pmd=0000000000000000
> Internal error: Oops: 96000046 [#1] PREEMPT SMP
> Modules linked in:
> ...
> Process Thread1 (pid: 3132, stack limit = 0xffff000027dd0000)
> CPU: 2 PID: 3132 Comm: Thread1 Tainted: G WC 4.14.130-ltsi-g28acae87 #1
> Hardware name: Board based on r8a7796 (DT)
> task: ffff80064f2aaa00 task.stack: ffff000027dd0000
> PC is at ravb_start_xmit+0x138/0x5a0
> LR is at ravb_start_xmit+0x40/0x5a0
> pc : [<ffff0000084d6324>] lr : [<ffff0000084d622c>] pstate: 600001c5
> sp : ffff000027dd3550
> x29: ffff000027dd3550
> x28: 0000000000000076
> x27: ffff80061035ff00
> x26: ffff000027dd3694
> x25: ffff80069624f800
> x24: ffff80069624f000
> x23: 0000000000000003
> x22: 0000000000000001
> x21: ffff80069624f000
> x20: 0000000000000000
> x19: ffff80069624f000
> x18: 0000000000000014
> x17: 0000ffff9b90ddb0
> x16: ffff00000867d07c
> x15: 0000155107b31031
> x14: 000409000c000000
> x13: 0000000003000001
> x12: 0100050010000001
> x11: 0000000003000001
> x10: 0100010010000001
> x9 : 20000000000000c0
> x8 : 0000000000000000
> x7 : ffff8006656f9388
> x6 : 0000000000000002
> x5 : 0000000000000000
> x4 : ffff8006656f929c
> x3 : ffff000027dd3694
> x2 : 0000000000000018
> x1 : 0000000000000000
> x0 : 0000000000000003
> Call trace:
> Exception stack(0xffff000027dd3410 to 0xffff000027dd3550)
> 3400: 0000000000000003 0000000000000000
> 3420: 0000000000000018 ffff000027dd3694 ffff8006656f929c 0000000000000000
> 3440: 0000000000000002 ffff8006656f9388 0000000000000000 20000000000000c0
> 3460: 0100010010000001 0000000003000001 0100050010000001 0000000003000001
> 3480: 000409000c000000 0000155107b31031 ffff00000867d07c 0000ffff9b90ddb0
> 34a0: 0000000000000014 ffff80069624f000 0000000000000000 ffff80069624f000
> 34c0: 0000000000000001 0000000000000003 ffff80069624f000 ffff80069624f800
> 34e0: ffff000027dd3694 ffff80061035ff00 0000000000000076 ffff000027dd3550
> 3500: ffff0000084d622c ffff000027dd3550 ffff0000084d6324 00000000600001c5
> 3520: ffff00000921d008 ffff8006159b0d00 0000ffffffffffff ffff0000084d622c
> 3540: ffff000027dd3550 ffff0000084d6324
> [<ffff0000084d6324>] ravb_start_xmit+0x138/0x5a0
> [<ffff000008699d60>] dev_hard_start_xmit+0xa8/0x24c
> [<ffff0000086c51c0>] sch_direct_xmit+0xb0/0x1a8
> [<ffff0000086c54cc>] __qdisc_run+0x214/0x2ec
> [<ffff00000869a348>] __dev_queue_xmit+0x35c/0x5b4
> [<ffff00000869a5b0>] dev_queue_xmit+0x10/0x18
> [<ffff000000b9765c>] register_vlan_dev+0xc74/0x10f8 [8021q]
> [<ffff000008699d60>] dev_hard_start_xmit+0xa8/0x24c
> [<ffff00000869a438>] __dev_queue_xmit+0x44c/0x5b4
> [<ffff00000869a5b0>] dev_queue_xmit+0x10/0x18
> [<ffff0000086a5b9c>] neigh_connected_output+0xc0/0xe4
> [<ffff0000086d6bd8>] ip_finish_output2+0x3c0/0x3fc
> [<ffff0000086d8178>] ip_finish_output+0xf8/0x1c4
> [<ffff0000086d8b74>] ip_mc_output+0x258/0x308
> [<ffff0000086d8400>] ip_local_out+0x44/0x54
> [<ffff0000086d9594>] ip_send_skb+0x1c/0xa8
> [<ffff0000086fea4c>] udp_send_skb+0x11c/0x244
> [<ffff000008701084>] udp_sendmsg+0x534/0x6bc
> [<ffff00000870b390>] inet_sendmsg+0x40/0xe0
> [<ffff00000867b588>] sock_sendmsg+0x3c/0x58
> [<ffff00000867bf18>] ___sys_sendmsg+0x228/0x278
> [<ffff00000867d03c>] __sys_sendmsg+0x58/0x98
> [<ffff00000867d08c>] SyS_sendmsg+0x10/0x20
> Exception stack(0xffff000027dd3ec0 to 0xffff000027dd4000)
> 3ec0: 0000000000000012 0000ffff8a7fdf18 0000000000004000 0000000000000000
> 3ee0: 0000ffff8a7ff258 0000ffff8a7ff150 0000ffff8a7ff840 0000000000000000
> 3f00: 00000000000000d3 0100010010000001 0000000003000001 0100050010000001
> 3f20: 0000000003000001 000409000c000000 0000000000000047 0000155107b31031
> 3f40: 0000ffff9b67dfb8 0000ffff9b90ddb0 0000000000000014 0000000000004000
> 3f60: 0000000000000012 0000ffff8a7fdf18 0000ffff780017b0 0000000000004000
> 3f80: 0000000000000010 0000000000000001 0000ffff8a7fdf00 0000ffff9000b770
> 3fa0: 0000000000000012 0000ffff8a7fde60 0000ffff9b90de10 0000ffff8a7fde60
> 3fc0: 0000ffff9b90de28 0000000080000000 0000000000000012 00000000000000d3
> 3fe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [<ffff0000080832c0>] el0_svc_naked+0x34/0x38
> Code: d37d7c01 d37d7c02 f90037a1 f9445f01 (f822683b)
> ---[ end trace eabda93d178d5bcb ]---
> Kernel panic - not syncing: Fatal exception in interrupt
> SMP: stopping secondary CPUs
> Kernel Offset: disabled
> CPU features: 0x1802004
> Memory Limit: 6144 MB
> -- cut --
>
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
Sorry for the long delay. :-<
[...]
MBR, Sergei
