Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758256AbZJLVSA (ORCPT ); Mon, 12 Oct 2009 17:18:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757886AbZJLVR7 (ORCPT ); Mon, 12 Oct 2009 17:17:59 -0400 Received: from ey-out-2122.google.com ([74.125.78.24]:43450 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751015AbZJLVR6 (ORCPT ); Mon, 12 Oct 2009 17:17:58 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=MztZOzFm/zH8sm2wspsaDUP5BsihbuzoZUjVc/gI8WU4BWtsO4NlG74ycte/UKVY7x uHIh+PSEZ0MJIaCv/qrDalaywsg5FZvP/XmxqOYd+sIntyItOXuXdflGE3mdAlRmIjPy bimxNX46ccbd566J/jiragJOzjKlETnm5fCVA= Date: Mon, 12 Oct 2009 23:16:46 +0200 From: Frederic Weisbecker To: Masami Hiramatsu Cc: Steven Rostedt , Ingo Molnar , lkml , systemtap , DLE , Thomas Gleixner , Arnaldo Carvalho de Melo , Mike Galbraith , Paul Mackerras , Peter Zijlstra , Christoph Hellwig , Ananth N Mavinakayanahalli , Jim Keniston , "Frank Ch. Eigler" Subject: Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction Message-ID: <20091012211645.GD4748@nowhere> References: <20091007222733.1684.32035.stgit@dhcp-100-2-132.bos.redhat.com> <20091007222807.1684.26880.stgit@dhcp-100-2-132.bos.redhat.com> <20091012173752.GB5059@nowhere> <4AD37FEF.9050807@redhat.com> <20091012194852.GB4748@nowhere> <4AD39002.2080907@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AD39002.2080907@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2121 Lines: 67 On Mon, Oct 12, 2009 at 04:22:26PM -0400, Masami Hiramatsu wrote: > Frederic Weisbecker wrote: >> On Mon, Oct 12, 2009 at 03:13:51PM -0400, Masami Hiramatsu wrote: >>> Frederic Weisbecker wrote: >>>> The conflict issue might not be obvious for a user desperately trying to set >>>> a kprobe. Even for other failcases, it might not be obvious (blacklisted >>>> symbols, syntax errors...) >>>> >>>> May be should you improve the error granularity and print a KERN_DEBUG >>>> message? >>> >>> Agreed, and kprobes error handling should be improved too (in the most cases, >>> it just returns -EINVAL). >>> >>> Thank you. >>> >> >> >> And btw, I'm enable to create a probe, neither through ftrace nor perf: >> >> $ sudo ./perf probe -P 'p:sys_close sys_close $retval' >> Adding new event: p:sys_close sys_close+0 $retval >> >> Error: Failed to create event: Invalid argument >> >> >> # echo 'p:sys_open sys_open $retval'> /debug/tracing/kprobe_events >> bash: echo: write error : Invalid argument >> >> I suspect I missed something very obvious with the syntax :) > > Ah, only kretprobe events can use $retval :-) > So, you should specify 'r' instead of 'p'. > > -P 'r:sys_close sys_close $retval' > Hehe, I was sure I was doing something silly but couldn't figure out what :-) So that works, at least without libdwarf, I can't test with it for now but this tool looks very promising. I really think it would be great to be able to cut the ./perf probe ./perf record ./perf trace batch into one step through a single ./perf probe -t -P "probe definition" [-a|cmdline] That would do the probe creation, the record, and stop once the given process finishes, or once we Ctrl+C (especially useful in wide tracing with -a, but sometimes also with processes). Not a lot of changes are required to do that. I can already see printk() whining on the horizon... Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/