Re: [PATCH v3 0/7] get_abi.pl: Check for missing symbols at the ABI specs

On Sat, Sep 18, 2021 at 11:52:10AM +0200, Mauro Carvalho Chehab wrote:

Hi Greg,

Add a new feature at get_abi.pl to optionally check for existing symbols
under /sys that won't match a "What:" inside Documentation/ABI.

Such feature is very useful to detect missing documentation for ABI.

This series brings a major speedup, plus it fixes a few border cases when
matching regexes that end with a ".*" or \d+.

patch 1 changes get_abi.pl logic to handle multiple What: lines, in
order to make the script more robust;

patch 2 adds the basic logic. It runs really quicky (up to 2
seconds), but it doesn't use sysfs softlinks.

Patch 3 adds support for parsing softlinks. It makes the script a
lot slower, making it take a couple of minutes to process the entire
sysfs files. It could be optimized in the future by using a graph,
but, for now, let's keep it simple.

Patch 4 adds an optional parameter to allow filtering the results
using a regex given by the user. When this parameter is used
(which should be the normal usecase), it will only try to find softlinks
if the sysfs node matches a regex.

Patch 5 improves the report by avoiding it to ignore What: that
ends with a wildcard.

Patch 6 is a minor speedup.  On a Dell Precision 5820, after patch 6, 
results are:

	$ time ./scripts/get_abi.pl undefined |sort >undefined && cat undefined| perl -ne 'print "$1\n" if (m#.*/(\S+) not found#)'|sort|uniq -c|sort -nr >undefined_symbols; wc -l undefined; wc -l undefined_symbols

	real	2m35.563s
	user	2m34.346s
	sys	0m1.220s
	7595 undefined
	896 undefined_symbols

Patch 7 makes a *huge* speedup: it basically switches a linear O(n^3)
search for links by a logic which handle symlinks using BFS. It
also addresses a border case that was making 'msi-irqs/\d+' regex to
be misparsed. 

After patch 7, it is 11 times faster:

	$ time ./scripts/get_abi.pl undefined |sort >undefined && cat undefined| perl -ne 'print "$1\n" if (m#.*/(\S+) not found#)'|sort|uniq -c|sort -nr >undefined_symbols; wc -l undefined; wc -l undefined_symbols

	real	0m14.137s
	user	0m12.795s
	sys	0m1.348s
	7030 undefined
	794 undefined_symbols

(the difference on the number of undefined symbols are due to the fix for
it to properly handle 'msi-irqs/\d+' regex)

-

While this series is independent from Documentation/ABI changes, it
works best when applied from this tree, which also contain ABI fixes
and a couple of additions of frequent missed symbols on my machine:

    https://git.kernel.org/pub/scm/linux/kernel/git/mchehab/devel.git/log/?h=get_undefined_abi_v3

I've taken all of these, but get_abi.pl seems to be stuck in an endless
loop or something.  I gave up and stopped it after 14 minutes.  It had
stopped printing out anything after finding all of the pci attributes
that are not documented :)

Anything I can do to help debug this?

thanks,

greg k-h