linux-kernel - Re: [PATCH] perf tools: Restore proper cwd on return from mnt ns

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Date:   Tue, 20 Nov 2018 12:56:04 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Krister Johansen <kjlx@...pleofstupid.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH] perf tools: Restore proper cwd on return from mnt ns

Em Tue, Nov 20, 2018 at 11:56:18AM +0100, Jiri Olsa escreveu:
> On Mon, Nov 19, 2018 at 08:10:06AM -0800, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Nov 01, 2018 at 06:00:01PM +0100, Jiri Olsa escreveu:
> > > Adding the current working directory to be part of the cookie
> > > and restoring it in the nsinfo__mountns_exit call.
> >  
> > > diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
> > > index cf8bd123cf73..fb0458b7e6aa 100644
> > > --- a/tools/perf/util/namespaces.c
> > > +++ b/tools/perf/util/namespaces.c
> > 
> > > @@ -199,9 +201,13 @@ void nsinfo__mountns_enter(struct nsinfo *nsi,
> > >  	if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
> > >  		return;
> >   
> > > +	oldcwd = get_current_dir_name();
> > 
> > Breaks the build with bionic (Android), where get_current_dir_name() is
> > not available:
> > 
> > /tmp/build/perf/libperf.a(libperf-in.o):hist.c:function nsinfo__mountns_enter: error: undefined reference to 'get_current_dir_name'
> > collect2: error: ld returned 1 exit status
> > Makefile.perf:534: recipe for target '/tmp/build/perf/perf' failed
> > make[2]: *** [/tmp/build/perf/perf] Error 1
> > Makefile.perf:206: recipe for target 'sub-make' failed
> > make[1]: *** [sub-make] Error 2
> > Makefile:69: recipe for target 'all' failed
> > make: *** [all] Error 2
> > make: Leaving directory '/git/linux/tools/perf'
> > [root@...enth ~]# 
> > 
> > The container builds are ongoing, its possoble that this becomes an
> > issue in uCLibc, wasn't on musl libc (Alpine Linux).
> 
> will check, thanks

I fixed this already, by adding a test for that get_current_dir_name()
function and a simple implementation based on strdup(getcwd(bf)), take a
look at my perf/urgent branch 

- Arnaldo