Re: [RFC] MAINTAINERS tag for cleanup robot

[Joe Perches <joe@xxxxxxxxxxx>]

On Sun, 2020-11-22 at 08:33 -0800, Tom Rix wrote:
> On 11/21/20 9:10 AM, Joe Perches wrote:
> > On Sat, 2020-11-21 at 08:50 -0800, trix@xxxxxxxxxx wrote:
> > > A difficult part of automating commits is composing the subsystem
> > > preamble in the commit log.  For the ongoing effort of a fixer producing
> > > one or two fixes a release the use of 'treewide:' does not seem 
> > > appropriate.
> > > 
> > > It would be better if the normal prefix was used.  Unfortunately normal is
> > > not consistent across the tree.
> > > 
> > > So I am looking for comments for adding a new tag to the MAINTAINERS file
> > > 
> > >   D: Commit subsystem prefix
> > > 
> > > ex/ for FPGA DFL DRIVERS
> > > 
> > >   D: fpga: dfl:
> > I'm all for it.  Good luck with the effort.  It's not completely trivial.
> > 
> > From a decade ago:
> > 
> > https://lore.kernel.org/lkml/1289919077.28741.50.camel@Joe-Laptop/
> > 
> > (and that thread started with extra semicolon patches too)
> 
> Reading the history, how about this.
> 
> get_maintainer.pl outputs a single prefix, if multiple files have the
> same prefix it works, if they don't its an error.
> 
> Another script 'commit_one_file.sh' does the call to get_mainainter.pl
> to get the prefix and be called by run-clang-tools.py to get the fixer
> specific message.

It's not whether the script used is get_maintainer or any other script,
the question is really if the MAINTAINERS file is the appropriate place
to store per-subsystem patch specific prefixes.

It is.

Then the question should be how are the forms described and what is the
inheritance priority.  My preference would be to have a default of
inherit the parent base and add basename(subsystem dirname).

Commit history seems to have standardized on using colons as the separator
between the commit prefix and the subject.

A good mechanism to explore how various subsystems have uses prefixes in
the past might be something like:

$ git log --no-merges --pretty='%s' -<commit_count> <subsystem_path> | \
  perl -n -e 'print substr($_, 0, rindex($_, ":") + 1) . "\n";' | \
  sort | uniq -c | sort -rn

Using 10000 for commit_count and drivers/scsi for subsystem_path, the
top 40 entries are below:

About 1% don't have a colon, and there is no real consistency even
within individual drivers below scsi.  For instance, qla2xxx:

     1      814 scsi: qla2xxx:
     2      691 scsi: lpfc:
     3      389 scsi: hisi_sas:
     4      354 scsi: ufs:
     5      339 scsi:
     6      291 qla2xxx:
     7      256 scsi: megaraid_sas:
     8      249 scsi: mpt3sas:
     9      200 hpsa:
    10      190 scsi: aacraid:
    11      174 lpfc:
    12      153 scsi: qedf:
    13      144 scsi: smartpqi:
    14      139 scsi: cxlflash:
    15      122 scsi: core:
    16      110 [SCSI] qla2xxx:
    17      108 ncr5380:
    18       98 scsi: hpsa:
    19       97 
    20       89 treewide:
    21       88 mpt3sas:
    22       86 scsi: libfc:
    23       85 scsi: qedi:
    24       84 scsi: be2iscsi:
    25       81 [SCSI] qla4xxx:
    26       81 hisi_sas:
    27       81 block:
    28       75 megaraid_sas:
    29       71 scsi: sd:
    30       69 [SCSI] hpsa:
    31       68 cxlflash:
    32       65 scsi: libsas:
    33       65 scsi: fnic:
    34       61 scsi: scsi_debug:
    35       60 scsi: arcmsr:
    36       57 be2iscsi:
    37       53 atp870u:
    38       51 scsi: bfa:
    39       50 scsi: storvsc:
    40       48 sd: