lkml.org 
[lkml]   [2015]   [Jul]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC 2/3] arm64: refactor save_stack_trace()
On 07/14/2015 10:31 PM, Steven Rostedt wrote:
> On Tue, 14 Jul 2015 21:47:10 +0900
> Jungseok Lee <jungseoklee85@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
>


\
 
 \ /
  Last update: 2015-07-15 02:41    [W:0.116 / U:0.288 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site