Re: [PATCH] scripts/bpf_doc: add __main__ judgement before main code

[Hu Haowen <2023002089@xxxxxxxxxxxxxxxx>]

On 2023/12/1 23:46, Daniel Borkmann wrote:
> Hi Hu,
>
> On 11/30/23 3:57 PM, Hu Haowen wrote:
> > When doing Python programming it is a nice convention to insert the if
> > statement `if __name__ == "__main__":` before any main code that does
> > actual functionalities to ensure the code will be executed only as a
> > script rather than as an imported module.  Hence attach the missing
> > judgement to bpf_doc.py.
> >
> > Signed-off-by: Hu Haowen <2023002089@xxxxxxxxxxxxxxxx>
>
> Thanks for the patch. What's the concrete value of this one? Do you plan
> to distribute the bpf_docs.py outside of the kernel tree? If it's not
> needed feels somewhat too much churn/marginal value.

Just noticed that the main code section does not follow the common rule
within the Python programming convention that any main code is ought to
be specified underneath the __name__ == "__main__" judgement to keep it
away from being executed when imported as a module wrongly. Hence I gave
this suggested change to both abide by this good convention and enhance
the main code's safety. After all it is recommended to have this change
carried out.

Thanks,
Hu Haowen


> >   scripts/bpf_doc.py | 81 +++++++++++++++++++++++-----------------------
> >   1 file changed, 41 insertions(+), 40 deletions(-)
> >
> > diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
> > index 61b7dddedc46..af2a87d97832 100755
> > --- a/scripts/bpf_doc.py
> > +++ b/scripts/bpf_doc.py
> > @@ -851,43 +851,44 @@ class PrinterHelpers(Printer):
> > ###############################################################################
> >   -# If script is launched from scripts/ from kernel tree and can access
> > -# ../include/uapi/linux/bpf.h, use it as a default name for the file 
> > to parse,
> > -# otherwise the --filename argument will be required from the 
> > command line.
> > -script = os.path.abspath(sys.argv[0])
> > -linuxRoot = os.path.dirname(os.path.dirname(script))
> > -bpfh = os.path.join(linuxRoot, 'include/uapi/linux/bpf.h')
> > -
> > -printers = {
> > -        'helpers': PrinterHelpersRST,
> > -        'syscall': PrinterSyscallRST,
> > -}
> > -
> > -argParser = argparse.ArgumentParser(description="""
> > -Parse eBPF header file and generate documentation for the eBPF API.
> > -The RST-formatted output produced can be turned into a manual page 
> > with the
> > -rst2man utility.
> > -""")
> > -argParser.add_argument('--header', action='store_true',
> > -                       help='generate C header file')
> > -if (os.path.isfile(bpfh)):
> > -    argParser.add_argument('--filename', help='path to 
> > include/uapi/linux/bpf.h',
> > -                           default=bpfh)
> > -else:
> > -    argParser.add_argument('--filename', help='path to 
> > include/uapi/linux/bpf.h')
> > -argParser.add_argument('target', nargs='?', default='helpers',
> > -                       choices=printers.keys(), help='eBPF API target')
> > -args = argParser.parse_args()
> > -
> > -# Parse file.
> > -headerParser = HeaderParser(args.filename)
> > -headerParser.run()
> > -
> > -# Print formatted output to standard output.
> > -if args.header:
> > -    if args.target != 'helpers':
> > -        raise NotImplementedError('Only helpers header generation is 
> > supported')
> > -    printer = PrinterHelpers(headerParser)
> > -else:
> > -    printer = printers[args.target](headerParser)
> > -printer.print_all()
> > +if __name__ == "__main__":
> > +    # If script is launched from scripts/ from kernel tree and can 
> > access
> > +    # ../include/uapi/linux/bpf.h, use it as a default name for the 
> > file to parse,
> > +    # otherwise the --filename argument will be required from the 
> > command line.
> > +    script = os.path.abspath(sys.argv[0])
> > +    linuxRoot = os.path.dirname(os.path.dirname(script))
> > +    bpfh = os.path.join(linuxRoot, 'include/uapi/linux/bpf.h')
> > +
> > +    printers = {
> > +            'helpers': PrinterHelpersRST,
> > +            'syscall': PrinterSyscallRST,
> > +    }
> > +
> > +    argParser = argparse.ArgumentParser(description="""
> > +    Parse eBPF header file and generate documentation for the eBPF API.
> > +    The RST-formatted output produced can be turned into a manual 
> > page with the
> > +    rst2man utility.
> > +    """)
> > +    argParser.add_argument('--header', action='store_true',
> > +                           help='generate C header file')
> > +    if (os.path.isfile(bpfh)):
> > +        argParser.add_argument('--filename', help='path to 
> > include/uapi/linux/bpf.h',
> > +                               default=bpfh)
> > +    else:
> > +        argParser.add_argument('--filename', help='path to 
> > include/uapi/linux/bpf.h')
> > +    argParser.add_argument('target', nargs='?', default='helpers',
> > +                           choices=printers.keys(), help='eBPF API 
> > target')
> > +    args = argParser.parse_args()
> > +
> > +    # Parse file.
> > +    headerParser = HeaderParser(args.filename)
> > +    headerParser.run()
> > +
> > +    # Print formatted output to standard output.
> > +    if args.header:
> > +        if args.target != 'helpers':
> > +            raise NotImplementedError('Only helpers header 
> > generation is supported')
> > +        printer = PrinterHelpers(headerParser)
> > +    else:
> > +        printer = printers[args.target](headerParser)
> > +    printer.print_all()