From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754199AbdEINlQ (ORCPT ); Tue, 9 May 2017 09:41:16 -0400 Received: from mail.kernel.org ([198.145.29.136]:45056 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753210AbdEINlO (ORCPT ); Tue, 9 May 2017 09:41:14 -0400 Date: Tue, 9 May 2017 09:41:02 -0400 From: Steven Rostedt To: Vegard Nossum Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] tracing: use %pF in trace_dump_stack() Message-ID: <20170509094102.35f98e97@gandalf.local.home> In-Reply-To: <20170509085004.7891-1-vegard.nossum@oracle.com> References: <20170509085004.7891-1-vegard.nossum@oracle.com> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 May 2017 10:50:04 +0200 Vegard Nossum wrote: > When using trace_dump_stack() you currently just get a list of function > names. > > It can be very useful to know exactly where a call came from, especially > if there are multiple calls from one function to another. > > By switching trace_dump_stack() to use %pF we get the function name and > the offset, which can also be further processed to give exact line number > information, like this: > > <...>-1087 3.... 3270529us : > => pty_write+0x45/0x50 > => n_tty_write+0x358/0x470 > => tty_write+0x189/0x2f0 > => __vfs_write+0x23/0x120 > => vfs_write+0xb3/0x1b0 > => SyS_write+0x44/0xa0 > => entry_SYSCALL_64_fastpath+0x18/0xad > > $ scripts/faddr2line vmlinux tty_write+0x189/0x2f0 > tty_write+0x189/0x2f0: > do_tty_write at drivers/tty/tty_io.c:1174 > (inlined by) tty_write at drivers/tty/tty_io.c:1257 I prefer not to see it by default. If you want to see it: echo 1 > /sys/kernel/debug/tracing/options/sym-offset NACK. -- Steve > > Signed-off-by: Vegard Nossum > --- > kernel/trace/trace_output.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index 02a4aeb22c47..879909efed33 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -1073,9 +1073,7 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter, > if (trace_seq_has_overflowed(s)) > break; > > - trace_seq_puts(s, " => "); > - seq_print_ip_sym(s, *p, flags); > - trace_seq_putc(s, '\n'); > + trace_seq_printf(s, " => %pF\n", (void *) *p); > } > > return trace_handle_return(s);