From 1a003fce7e4f8460ef3256fb5d958fb5c6cc631e Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <masahiroy@kernel.org>
Date: Wed, 2 Sep 2020 21:49:59 +0900
Subject: [PATCH] scripts/tags.sh: remove m, v, x tag kinds from exuberant tags

Exuberant Ctags supports the following kinds of tags:

  $ ctags --list-kinds=c
  c  classes
  d  macro definitions
  e  enumerators (values inside an enumeration)
  f  function definitions
  g  enumeration names
  l  local variables [off]
  m  class, struct, and union members
  n  namespaces
  p  function prototypes [off]
  s  structure names
  t  typedefs
  u  union names
  v  variable definitions
  x  external and forward variable declarations [off]

This commit excludes 'm', 'v', and 'x'.

Peter Zijlstra states:
"The problem with that is that, for example, the tag 'mutex' appears a
mere 505 times, 492 of those are structure members. However it is _far_
more likely that someone wants the struct definition when looking for
the mutex tag than any of those members."
(https://lkml.org/lkml/2020/8/6/512")

So, 'm' is rather annoying than useful. For the same reason, it seems
better to turn off 'v'.

You may argue about the criteria, but we need to draw a line somewhere
to make it reasonable for the majority of people.

We flipped 'p' and 'x' in the past:

[1] commit f6333eb4e788 ("kbuild: Add ctags support for function
    prototypes and external variable declarations") added 'p' and 'x',
    but did not explain when they are actually useful.

[2] commit 7db86dc97fb0 ("ctags: usability fix") removed 'p' and 'x',
    stating both of them make no real sense.

[3] commit 0a18a9386c05 ("tags: put function prototypes back!")
    re-added 'p' and 'x', but the commit log only mentioned 'p'.

OK, [3] clearly explained why 'p' is useful, but turned --c-kinds=+px
into --c-kinds=-px. So, 'x' was also (accidentally?) disabled. I think
it should have been --c-kinds=+p-x, or more simply --c-kinds=+p since
'x' is off by default.

It seems a bug of [3], so I disabled 'x' to get back the pre-[3]
behavior.

'make tags' and 'make TAGS' will run faster, create much smaller tags
if Ctags is exuberant.

Reviewed-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
 scripts/tags.sh | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/scripts/tags.sh b/scripts/tags.sh
index 32d3f53af10b..440f4ecad43b 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -179,19 +179,6 @@ regex_c=(
 	'/^DEF_PCI_AC_\(\|NO\)RET(\([[:alnum:]_]*\).*/\2/'
 	'/^PCI_OP_READ(\(\w*\).*[1-4])/pci_bus_read_config_\1/'
 	'/^PCI_OP_WRITE(\(\w*\).*[1-4])/pci_bus_write_config_\1/'
-	'/\<DEFINE_\(RT_MUTEX\|MUTEX\|SEMAPHORE\|SPINLOCK\)(\([[:alnum:]_]*\)/\2/v/'
-	'/\<DEFINE_\(RAW_SPINLOCK\|RWLOCK\|SEQLOCK\)(\([[:alnum:]_]*\)/\2/v/'
-	'/\<DECLARE_\(RWSEM\|COMPLETION\)(\([[:alnum:]_]\+\)/\2/v/'
-	'/\<DECLARE_BITMAP(\([[:alnum:]_]*\)/\1/v/'
-	'/\(^\|\s\)\(\|L\|H\)LIST_HEAD(\([[:alnum:]_]*\)/\3/v/'
-	'/\(^\|\s\)RADIX_TREE(\([[:alnum:]_]*\)/\2/v/'
-	'/\<DEFINE_PER_CPU([^,]*, *\([[:alnum:]_]*\)/\1/v/'
-	'/\<DEFINE_PER_CPU_SHARED_ALIGNED([^,]*, *\([[:alnum:]_]*\)/\1/v/'
-	'/\<DECLARE_WAIT_QUEUE_HEAD(\([[:alnum:]_]*\)/\1/v/'
-	'/\<DECLARE_\(TASKLET\|WORK\|DELAYED_WORK\)(\([[:alnum:]_]*\)/\2/v/'
-	'/\(^\s\)OFFSET(\([[:alnum:]_]*\)/\2/v/'
-	'/\(^\s\)DEFINE(\([[:alnum:]_]*\)/\2/v/'
-	'/\<\(DEFINE\|DECLARE\)_HASHTABLE(\([[:alnum:]_]*\)/\2/v/'
 	'/\<DEFINE_ID\(R\|A\)(\([[:alnum:]_]\+\)/\2/'
 	'/\<DEFINE_WD_CLASS(\([[:alnum:]_]\+\)/\1/'
 	'/\<ATOMIC_NOTIFIER_HEAD(\([[:alnum:]_]\+\)/\1/'
@@ -255,7 +242,7 @@ exuberant()
 	-I EXPORT_SYMBOL,EXPORT_SYMBOL_GPL,ACPI_EXPORT_SYMBOL   \
 	-I DEFINE_TRACE,EXPORT_TRACEPOINT_SYMBOL,EXPORT_TRACEPOINT_SYMBOL_GPL \
 	-I static,const						\
-	--extra=+fq --c-kinds=+px --fields=+iaS --langmap=c:+.h \
+	--extra=+fq --c-kinds=+p-mv --fields=+iaS --langmap=c:+.h \
 	"${regex[@]}"
 
 	setup_regex exuberant kconfig
-- 
2.25.1