netdev - Re: [PATCH bpf-next v3 2/4] bpf: sockmap, add hash map support

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Date:   Sun, 29 Apr 2018 09:41:54 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     daniel@...earbox.net, ast@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v3 2/4] bpf: sockmap, add hash map support

On 04/29/2018 09:16 AM, Alexei Starovoitov wrote:
> On Sat, Apr 28, 2018 at 08:41:28PM -0700, John Fastabend wrote:
>> Sockmap is currently backed by an array and enforces keys to be
>> four bytes. This works well for many use cases and was originally
>> modeled after devmap which also uses four bytes keys. However,
>> this has become limiting in larger use cases where a hash would
>> be more appropriate. For example users may want to use the 5-tuple
>> of the socket as the lookup key.
>>
>> To support this add hash support.
>>
>> Signed-off-by: John Fastabend <john.fastabend@...il.com>
> ...
>>  enum bpf_prog_type {
>> @@ -1835,7 +1836,10 @@ struct bpf_stack_build_id {
>>  	FN(msg_pull_data),		\
>>  	FN(bind),			\
>>  	FN(xdp_adjust_tail),		\
>> -	FN(skb_get_xfrm_state),
>> +	FN(skb_get_xfrm_state),		\
>> +	FN(sock_hash_update),		\
>> +	FN(msg_redirect_hash),		\
>> +	FN(sk_redirect_hash),
> 
> Documentation for new helpers is missing. Please add it in this commit.
> 

OK.

> Also running test_sockmap in the latest bpf-next I see:
> [TEST 81]: (10, 1024, 256, sendpage, pass,apply,): [   14.227128] WARNING: CPU: 1 PID: 202 at ../net/core/stream.c:206 sk_stream_kill_queues+0x3ca/0x540
> [   14.228209] Modules linked in:
> [   14.228583] CPU: 1 PID: 202 Comm: test_sockmap Not tainted 4.17.0-rc2-00438-gfcf85729d8ef #941
> [   14.229595] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-1.el7.centos 04/01/2014
> [   14.230649] RIP: 0010:sk_stream_kill_queues+0x3ca/0x540
> [   14.231251] RSP: 0018:ffff880111717d00 EFLAGS: 00010202
> [   14.231855] RAX: 0000000000000000 RBX: ffff8801127f8978 RCX: 1ffff100224ff138
> [   14.232664] RDX: 0000000000000000 RSI: 0000000000000f01 RDI: ffff8801127f89c0
> [   14.233521] RBP: ffff8801127f8948 R08: ffffed00224ff122 R09: ffffed00224ff121
> [   14.234342] R10: ffff8801127f890b R11: ffffed00224ff122 R12: ffff8801127f8998
> [   14.235169] R13: ffff8801127f88a8 R14: ffff8801127f8880 R15: ffff8801127f8930
> [   14.235987] FS:  00007f3d46898700(0000) GS:ffff88011b080000(0000) knlGS:0000000000000000
> [   14.236946] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   14.237607] CR2: 00007f3d45e3caf0 CR3: 0000000112da0001 CR4: 00000000000606e0
> [   14.238433] Call Trace:
> [   14.238741]  ? tcp_v4_destroy_sock+0x273/0x4d0
> [   14.239259]  inet_csk_destroy_sock+0x157/0x390
> [   14.239815]  tcp_close+0x683/0xf60
> [   14.240214]  inet_release+0xd6/0x1b0
> [   14.240636]  sock_release+0x7e/0x190
> [   14.241090]  sock_close+0xe/0x20
> [   14.241593]  __fput+0x22f/0x720
> [   14.241981]  task_work_run+0x10b/0x190
> [   14.242425]  exit_to_usermode_loop+0xd2/0xf0
> [   14.242963]  do_syscall_64+0x1d5/0x270
> [   14.243410]  ? page_fault+0x8/0x30
> [   14.243830]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> and
> 
> [TEST 84]: (1, 1, 1, sendmsg, pass,cork,): [   14.317100] WARNING: CPU: 1 PID: 66 at ../net/ipv4/af_inet.c:156 inet_sock_destruct+0x570/0x7b0
> [   14.318147] Modules linked in:
> [   14.318522] CPU: 1 PID: 66 Comm: kworker/1:1 Tainted: G        W         4.17.0-rc2-00438-gfcf85729d8ef #941
> [   14.319674] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-1.el7.centos 04/01/2014
> [   14.320764] Workqueue: events smap_gc_work
> [   14.321262] RIP: 0010:inet_sock_destruct+0x570/0x7b0
> [   14.321829] RSP: 0018:ffff880118617d08 EFLAGS: 00010206
> [   14.322415] RAX: 0000000000000ffc RBX: ffff8801127f9980 RCX: ffffffff82c7ac64
> [   14.323221] RDX: 1ffff100224ff34f RSI: 0000000000000004 RDI: ffff8801127f9a78
> [   14.324054] RBP: ffff8801127f9ac4 R08: ffffed00224ff359 R09: ffffed00224ff358
> [   14.324860] R10: ffff8801127f9ac7 R11: ffffed00224ff359 R12: ffff880111107688
> [   14.325661] R13: dffffc0000000000 R14: ffff880111107688 R15: dead000000000100
> [   14.326503] FS:  0000000000000000(0000) GS:ffff88011b080000(0000) knlGS:0000000000000000
> [   14.327413] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   14.328091] CR2: 00007f3d45e3caf0 CR3: 0000000003a0e004 CR4: 00000000000606e0
> [   14.328936] Call Trace:
> [   14.329225]  __sk_destruct+0x45/0x460
> [   14.329646]  smap_gc_work+0x69f/0x950
> [   14.330102]  process_one_work+0x7be/0x1230
> [   14.330600]  worker_thread+0xd9/0x1080
> [   14.331059]  ? rescuer_thread+0xd70/0xd70
> [   14.331543]  kthread+0x29e/0x390
> [   14.331945]  ? kthread_create_worker_on_cpu+0xb0/0xb0
> [   14.332555]  ret_from_fork+0x1f/0x30
> 
> Please send a fix for this issue first.
> I'd like to see test_sockmap being clean before adding hash support to sockmap.
> 

Sure, I'll have a fix shortly.