On Fri, Jun 30, 2017 at 05:50:57PM -0400, Steven Rostedt wrote: > On Fri, 30 Jun 2017 11:17:50 -0600 > Michael Sartain <[email protected]> wrote: > > > Export the cached pid / tgid mappings to userspace. This allows user > > apps to translate the pids from a trace to their respective thread > > group. > > > > Example saved_tgids file with pid / tgid values separated by ' ': > > > > # cat saved_tgids > > 1048 1048 > > 1047 1047 > > 7 7 > > 1049 1047 > > 1054 1047 > > 1053 1047 > > > > [ Impact: let userspace apps reading binary buffer know tgid's ] > > Impact line? Linus put a kibosh on this a while ago... > > https://lkml.org/lkml/2009/4/15/296 > > Although, I will admit that this line is actually useful. Just remove > the brackets.
Ah, thank you. I saw it used in the previous cmdline patch and used it as a reference. > > Signed-off-by: Michael Sartain <[email protected]> > > --- > > kernel/trace/trace.c | 60 > > +++++++++++++++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 59 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index 68c214b..ca84c97 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -4692,6 +4692,7 @@ static const struct file_operations > > tracing_readme_fops = { > > static void *saved_cmdlines_next(struct seq_file *m, void *v, loff_t *pos) > > { > > unsigned int *ptr = v; > > + long tgid_check = (long) m->private; > > I really don't like the subtle use of having m->private != NULL mean > this is for tgid listing. > > In fact, I don't see the purpose of reusing the seq code. The cmdlines > and tgid map are quite different. Just create its own functions. I > don't see the benefit of trying to reuse this except for making the > code more complex. Will do. Joel was also kind enough to send me feedback about RFCs and merge windows, etc. so I apologize - wasn't trying to get anything by anyone, just that this is my first real patch and I've obviously got a lot to learn here. Thank you for the comments. I'll fix and resubmit next week. -Mike
