Re: [PATCH bpf-next] bpftool: Search for tracefs at /sys/kernel/tracing first

[Quentin Monnet <qmo@kernel.org>]

2025-09-15 13:33 UTC+0200 ~ Daniel Borkmann <daniel@iogearbox.net>
> On 9/12/25 12:43 PM, Quentin Monnet wrote:
> [...]
>> diff --git a/tools/bpf/bpftool/tracelog.c b/tools/bpf/bpftool/tracelog.c
>> index 31d806e3bdaa..49828a4f60c2 100644
>> --- a/tools/bpf/bpftool/tracelog.c
>> +++ b/tools/bpf/bpftool/tracelog.c
>> @@ -57,10 +57,8 @@ find_tracefs_mnt_single(unsigned long magic, char
>> *mnt, const char *mntpt)
>>   static bool get_tracefs_pipe(char *mnt)
>>   {
>>       static const char * const known_mnts[] = {
>> -        "/sys/kernel/debug/tracing",
>>           "/sys/kernel/tracing",
>> -        "/tracing",
>> -        "/trace",
>> +        "/sys/kernel/debug/tracing",
>>       };
>>       const char *pipe_name = "/trace_pipe";
>>       const char *fstype = "tracefs";
>> @@ -96,11 +94,11 @@ static bool get_tracefs_pipe(char *mnt)
>>         p_info("could not find tracefs, attempting to mount it now");
>>       /* Most of the time, tracefs is automatically mounted by debugfs at
>> -     * /sys/kernel/debug/tracing when we try to access it. If we
>> could not
>> +     * /sys/kernel/tracing when we try to access it. If we could not
>>        * find it, it is likely that debugfs is not mounted. Let's give
>> one
> 
> nit: Should this comment be tweaked further, or maybe even removed
> completely
> given the now stale references to debugfs there?


Hi Daniel! Re-reading it, I realise my change for the comment is not
even correct, /sys/kernel/tracing is not mounted automatically. So yes,
I'll send a v2 to remove it. Thanks for the review!

Quentin