From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752771AbbGOAU4 (ORCPT ); Tue, 14 Jul 2015 20:20:56 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:33898 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751769AbbGOAUy (ORCPT ); Tue, 14 Jul 2015 20:20:54 -0400 Message-ID: <55A5A75A.1060401@linaro.org> Date: Wed, 15 Jul 2015 09:20:42 +0900 From: AKASHI Takahiro User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Steven Rostedt , Jungseok Lee CC: catalin.marinas@arm.com, will.deacon@arm.com, olof@lixom.net, broonie@kernel.org, david.griego@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 2/3] arm64: refactor save_stack_trace() References: <1436765375-7119-1-git-send-email-takahiro.akashi@linaro.org> <1436765375-7119-3-git-send-email-takahiro.akashi@linaro.org> <20150714093154.4d73e551@gandalf.local.home> In-Reply-To: <20150714093154.4d73e551@gandalf.local.home> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/14/2015 10:31 PM, Steven Rostedt wrote: > On Tue, 14 Jul 2015 21:47:10 +0900 > Jungseok Lee 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 > From mboxrd@z Thu Jan 1 00:00:00 1970 From: takahiro.akashi@linaro.org (AKASHI Takahiro) Date: Wed, 15 Jul 2015 09:20:42 +0900 Subject: [RFC 2/3] arm64: refactor save_stack_trace() In-Reply-To: <20150714093154.4d73e551@gandalf.local.home> References: <1436765375-7119-1-git-send-email-takahiro.akashi@linaro.org> <1436765375-7119-3-git-send-email-takahiro.akashi@linaro.org> <20150714093154.4d73e551@gandalf.local.home> Message-ID: <55A5A75A.1060401@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 07/14/2015 10:31 PM, Steven Rostedt wrote: > On Tue, 14 Jul 2015 21:47:10 +0900 > Jungseok Lee 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 >