On 07/14/2015 10:31 PM, Steven Rostedt wrote:
On Tue, 14 Jul 2015 21:47:10 +0900
Jungseok Lee <jungseokle...@gmail.com> wrote:
Is the below example an unexpected result?
Entry 17 and 18 are ftrace_call and ftrace_ops_no_ops, respectively.
[snip]
Note, function tracing does not disable interrupts. This looks to be
that an interrupt came in while __aloc_skb() was being traced.
Yeah, I think so, too. But if my insight is correct, it's not __alloc_skb()
but one of functions that it calls. As I said in the commit log message
of patch[1/3], the exact traced function will not be listed by
save_stack_trace() because we don't create a stack frame at mcount().
I think this is a flaw in the current implementation (on x86).
what do you think, Steve?
-Takahiro AKASHI
-- Steve
17) 4080 168 ftrace_ops_no_ops+0xb4/0x16c
18) 3912 32 ftrace_call+0x0/0x4
19) 3880 144 __alloc_skb+0x48/0x180
20) 3736 96 alloc_skb_with_frags+0x74/0x234
21) 3640 112 sock_alloc_send_pskb+0x1d0/0x294
22) 3528 160 sock_alloc_send_skb+0x44/0x54
23) 3368 64 __ip_append_data.isra.40+0x78c/0xb48
24) 3304 224 ip_append_data.part.42+0x98/0xe8
25) 3080 112 ip_append_data+0x68/0x7c
26) 2968 96 icmp_push_reply+0x7c/0x144
27) 2872 96 icmp_send+0x3c0/0x3c8
28) 2776 192 __udp4_lib_rcv+0x5b8/0x684
29) 2584 96 udp_rcv+0x2c/0x3c
30) 2488 32 ip_local_deliver+0xa0/0x224
31) 2456 48 ip_rcv+0x360/0x57c
32) 2408 64 __netif_receive_skb_core+0x4d0/0x80c
33) 2344 128 __netif_receive_skb+0x24/0x84
34) 2216 32 process_backlog+0x9c/0x15c
35) 2184 80 net_rx_action+0x1ec/0x32c
36) 2104 160 __do_softirq+0x114/0x2f0
37) 1944 128 do_softirq+0x60/0x68
38) 1816 32 __local_bh_enable_ip+0xb0/0xd4
39) 1784 32 ip_finish_output+0x1f4/0xabc
40) 1752 96 ip_output+0xf0/0x120
41) 1656 64 ip_local_out_sk+0x44/0x54
42) 1592 32 ip_send_skb+0x24/0xbc
43) 1560 48 udp_send_skb+0x1b4/0x2f4
44) 1512 80 udp_sendmsg+0x2a8/0x7a0
45) 1432 272 inet_sendmsg+0xa0/0xd0
46) 1160 48 sock_sendmsg+0x30/0x78
47) 1112 32 ___sys_sendmsg+0x15c/0x26c
48) 1080 400 __sys_sendmmsg+0x94/0x180
49) 680 320 SyS_sendmmsg+0x38/0x54
50) 360 360 el0_svc_naked+0x20/0x28
Best Regards
Jungseok Lee
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