Re: [PATCH bpf-next v3 2/2] selftests/bpf: use canonical ftrace path

[John Fastabend]

Ross Zwisler wrote:
> On Fri, Mar 10, 2023 at 06:33:52PM -0500, Steven Rostedt wrote:
> > On Fri, 10 Mar 2023 10:52:09 -0700
> > zwisler@xxxxxxxxxx wrote:
> > 
> > > diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > > index 156743cf5870..4fa61ac8a0ee 100644
> > > --- a/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > > +++ b/tools/testing/selftests/bpf/get_cgroup_id_user.c
> > > @@ -86,8 +86,12 @@ int main(int argc, char **argv)
> > >  	pid = getpid();
> > >  	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
> > >  
> > > -	snprintf(buf, sizeof(buf),
> > > -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > > +	else
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > 
> > I don't know how the BPF folks feel, but I do know some kernel developers
> > prefer that if you need to break a single command into multiple lines that
> > you then need to add brackets around it. As it makes it easier to read.
> > 
> > 	if (access("/sys/kernel/tracing/trace", F_OK) == 0) {
> > 		snprintf(buf, sizeof(buf),
> > 			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > 	} else {
> > 		snprintf(buf, sizeof(buf),
> > 			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > 	}
> > 
> > 
> > 
> > >  	efd = open(buf, O_RDONLY, 0);
> > >  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
> > >  		goto close_prog;
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > > index 113dba349a57..22be0a9a5a0a 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> > > @@ -338,7 +338,12 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
> > >  	 * Filtering out duplicates by using hashmap__add, which won't
> > >  	 * add existing entry.
> > >  	 */
> > > -	f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> > > +
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
> > > +	else
> > > +		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
> > > +
> > >  	if (!f)
> > >  		return -EINVAL;
> > >  
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > > index c717741bf8b6..60f92fd3c37a 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/task_fd_query_tp.c
> > > @@ -17,8 +17,12 @@ static void test_task_fd_query_tp_core(const char *probe_name,
> > >  	if (CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno))
> > >  		goto close_prog;
> > >  
> > > -	snprintf(buf, sizeof(buf),
> > > -		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/tracing/events/%s/id", probe_name);
> > > +	else
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > 
> > Same here.
> > 
> > >  	efd = open(buf, O_RDONLY, 0);
> > >  	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
> > >  		goto close_prog;
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > > index 770fcc3bb1ba..d3e377fa8e9b 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/tp_attach_query.c
> > > @@ -16,8 +16,12 @@ void serial_test_tp_attach_query(void)
> > >  	for (i = 0; i < num_progs; i++)
> > >  		obj[i] = NULL;
> > >  
> > > -	snprintf(buf, sizeof(buf),
> > > -		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
> > > +	if (access("/sys/kernel/tracing/trace", F_OK) == 0)
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/tracing/events/sched/sched_switch/id");
> > > +	else
> > > +		snprintf(buf, sizeof(buf),
> > > +			 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
> > 
> > and here.
> > 
> > But perhaps the BPF folks don't care?
> 
> Sure, I agree that this is more readable.  I'll gather your Reviewed-by for
> patch #1, make this change, rebase to the current bpf/bpf-next and send out
> v4.


Also for the patch. LGTM

Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>