From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35826) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bwWMW-0000fx-AK for qemu-devel@nongnu.org; Tue, 18 Oct 2016 11:31:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bwWMS-0004CL-U4 for qemu-devel@nongnu.org; Tue, 18 Oct 2016 11:31:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57820) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1bwWMS-0004CA-MZ for qemu-devel@nongnu.org; Tue, 18 Oct 2016 11:31:28 -0400 Date: Tue, 18 Oct 2016 16:31:24 +0100 From: "Daniel P. Berrange" Message-ID: <20161018153124.GB15199@redhat.com> Reply-To: "Daniel P. Berrange" References: <147648037766.14770.15179642645810274907.stgit@bahia> <20161018151646.GI12728@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20161018151646.GI12728@redhat.com> Subject: Re: [Qemu-devel] [PATCH] trace: fix group name generation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: Greg Kurz , qemu-devel@nongnu.org, Stefan Hajnoczi On Tue, Oct 18, 2016 at 04:16:46PM +0100, Daniel P. Berrange wrote: > On Fri, Oct 14, 2016 at 04:31:01PM -0500, Eric Blake wrote: > > On 10/14/2016 04:26 PM, Greg Kurz wrote: > > > Since commit "80dd5c4918ab trace: introduce a formal group name for trace > > > events", tracetool generates C variable names and macro definitions out > > > of the path to the trace-events-all file. > > > > > > The current code takes care of turning '/' and '-' characters into > > > underscores so that the resulting names are valid C tokens. This is > > > enough because these are the only illegal characters that appear in > > > a relative path within the QEMU source tree. > > > > > > Things are different for out of tree builds where the path may contain > > > arbitrary character combinations, causing tracetool to generate invalid > > > names. > > > > > > > > This patch ensures that only letters [A-Za-z], digits [0-9] and underscores > > > are kept. All other characters are turned into underscores. Also, since the > > > first character of C symbol names cannot be a digit, an underscore is > > > prepended to the group name. > > > > > > Signed-off-by: Greg Kurz > > > --- > > > scripts/tracetool.py | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/scripts/tracetool.py b/scripts/tracetool.py > > > index 629b2593c846..b81b834db924 100755 > > > --- a/scripts/tracetool.py > > > +++ b/scripts/tracetool.py > > > @@ -70,7 +70,7 @@ def make_group_name(filename): > > > > > > if dirname == "": > > > return "common" > > > - return re.sub(r"/|-", "_", dirname) > > > + return "_" + re.sub(r"[^\w]", "_", dirname) > > > > This STILL doesn't solve the complaint that the build is now dependent > > on the location. Why can't we STRIP off any prefix prior to the in-tree > > portion of the naming that we know is sane, instead of munging the > > prefix but in the process creating source code that generates with > > different lengths? > > > > Ideally, compiling twice, once in directory 'a', and the second time in > > directory 'aaaaaaaaaaaaaaaaaaaaaaaaaaaa', should not make a noticeable > > difference in the final size of the executable due to the difference in > > lengths of the debugging symbols used to record the longer name of the > > second directory being encoded into lots of macro names. > > This is a mistake on my part - the code was supposed to be stripping > off the build directory prefix, leaving only the relative path to the > file wrt source directory. The code is simply wrong as is. Ah ha, I realize what the issue is. Currently in git master we have multiple trace-events files and we merge them into a single trace-events-all file, then generate the various bits we need. This trace-events-all file is naturally in the build dir, not the source dir In my trace events patch build refactor series though, I have stopped creating trace-events-all, and we instead generate bits directly from the trace-events files in source dir. So this problem only appeared because we've only merge part of my series into master. IOW, I think Greg's proposed fix is fine as a workaround - once the rest of my patches merge, build dir should not pollute this at all. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|