Re: [PATCH bpf 1/4] selftests: bpf: use a temporary file in test_sockmap

[John Fastabend]

Martin Lau wrote:
> On Thu, Jan 23, 2020 at 04:59:30PM +0000, Lorenz Bauer wrote:
> > Use a proper temporary file for sendpage tests. This means that running
> > the tests doesn't clutter the working directory, and allows running the
> > test on read-only filesystems.
> > 
> > Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
> > ---
> >  tools/testing/selftests/bpf/test_sockmap.c | 15 +++++----------
> >  1 file changed, 5 insertions(+), 10 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/bpf/test_sockmap.c b/tools/testing/selftests/bpf/test_sockmap.c
> > index 4a851513c842..779e11da979c 100644
> > --- a/tools/testing/selftests/bpf/test_sockmap.c
> > +++ b/tools/testing/selftests/bpf/test_sockmap.c
> > @@ -331,7 +331,7 @@ static int msg_loop_sendpage(int fd, int iov_length, int cnt,
> >  	FILE *file;
> >  	int i, fp;
> >  
> > -	file = fopen(".sendpage_tst.tmp", "w+");
> > +	file = tmpfile();
> >  	if (!file) {
> >  		perror("create file for sendpage");
> >  		return 1;
> > @@ -340,13 +340,8 @@ static int msg_loop_sendpage(int fd, int iov_length, int cnt,
> >  		fwrite(&k, sizeof(char), 1, file);
> >  	fflush(file);
> >  	fseek(file, 0, SEEK_SET);
> > -	fclose(file);
> >  
> > -	fp = open(".sendpage_tst.tmp", O_RDONLY);
> > -	if (fp < 0) {
> > -		perror("reopen file for sendpage");
> > -		return 1;
> > -	}
> > +	fp = fileno(file);
> It may be better to keep fp == -1 check here.
> It is not clear to me the original intention of reopen.
> I would defer to John for comment.
> 

Seeing fileno shouldn't fail seems OK to me.

> >  
> >  	clock_gettime(CLOCK_MONOTONIC, &s->start);
> >  	for (i = 0; i < cnt; i++) {