From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frank Rowand Subject: Re: [PATCH] of: introduce event tracepoints for dynamic device_node lifecyle Date: Thu, 20 Apr 2017 12:34:46 -0700 Message-ID: <58F90D56.9070602@gmail.com> References: <1492475525-10827-1-git-send-email-tyreld@linux.vnet.ibm.com> <58F6AA35.2040902@gmail.com> <87efwp6v4e.fsf@concordia.ellerman.id.au> <1d51a229-612b-bf09-93d5-6e43b476e2cf@gmail.com> <58F83C66.7030806@gmail.com> <64505d40-926d-b302-4ff3-dff71aa5018a@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <64505d40-926d-b302-4ff3-dff71aa5018a-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tyrel Datwyler , Michael Ellerman , Tyrel Datwyler , robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Cc: linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, nfont-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org, mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org List-Id: devicetree@vger.kernel.org On 04/20/17 09:51, Tyrel Datwyler wrote: > On 04/19/2017 09:43 PM, Frank Rowand wrote: > < snip > >> The call stack could easily be post-processed, for example using addr2line. >> Here is the call stack for when the refcount incremented to 23 from 22 (or >> more accurately, to 22 from 21): >> >> 0xc0d00e3c Line 857 of "init/main.c" >> 0xc03017d0 Line 792 of "init/main.c" >> 0xc0d3a234 Line 528 of "drivers/of/platform.c" >> 0xc0810684 Line 503 of "drivers/of/platform.c" >> 0xc081061c Line 267 of "include/linux/of.h" >> 0xc080d928 Line 815 of "drivers/of/base.c" >> >> Which ends up being this code: >> >> of_platform_default_populate_init() >> of_platform_default_populate() >> of_platform_populate() >> [[ of_find_node_by_path("/") ]] >> [[ of_find_node_opts_by_path(path, NULL) ]] >> of_node_get(of_root) >> >> Note that some functions can be left out of the ARM call stack, with >> a return going back more than one level. The functions in the call >> list above that are enclosed in '[[' and ']]' were found by source >> inspection in those cases. > > The same thing is encountered in ppc64 stack traces. I assume it is > generally inlining of small functions, but I've never actually verified > that theory. Probably should take the time to investigate, or just ask > someone. Yes, inlining small functions is one reason for this. Another case I often find is that when function A calls function B calls function C. If the final statement of function B is 'return C()' then there is no need for function C to return through function B, it can instead return directly to function A. (That is more a conceptual hand-waving of the idea, not the actual way the compiler implements it. Take this with a grain of salt, I'm not a compiler guy.) < snip > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html