linux.git/scripts/kconfig/menu.c, branch v4.16-rc2

kconfig: make "Selected by:" and "Implied by:" readable

2018-01-25T12:53:00+00:00

Reverse dependency expressions can get rather unwieldy, especially if
a symbol is selected by more than a handful of other symbols. I.e. it's
possible to have near endless expressions like:
   A && B && !C || D || F && (G || H) || [...]

Chop these expressions into actually readable chunks:
   - A && B && !C
   - D
   - F && (G || H)
   - [...]

I.e. transform the top level OR tokens into newlines and prepend each
line with a minus. This makes the "Selected by:" and "Implied by:" blurb
much easier to read. This is done only if there is more than one top
level OR. "Depends on:" and "Range :" were deliberately left as they are.

Based on idea from Paul Bolle.

Suggested-by: Paul Bolle 
Signed-off-by: Petr Vorel 
Signed-off-by: Masahiro Yamada

kconfig: Clarify menu and 'if' dependency propagation

2018-01-21T18:30:09+00:00

It is not obvious that the last two cases refer to menus and ifs,
respectively, in the conditional that sets 'parentdep'.

Automatic submenu creation is done later, so the parent can't be a
symbol here.

No functional changes. Only comments added.

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada

kconfig: Document 'if' flattening logic

2018-01-21T16:49:30+00:00

It is not obvious that this might refer to an 'if', making the code
pretty cryptic:

	if (menu->list && (!menu->prompt || !menu->prompt->text)) {

Kconfig keeps the 'if' menu nodes even after flattening. Reflect that in
the example to be accurate.

No functional changes. Only comments added.

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada

kconfig: Clarify choice dependency propagation

2018-01-21T15:49:32+00:00

It's easy to miss that choices are special-cased to pass on their mode
as the parent dependency.

No functional changes. Only comments added.

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada

kconfig: Document SYMBOL_OPTIONAL logic

2018-01-21T15:49:32+00:00

Not obvious, especially if you don't already know how choices are
implemented.

No functional changes. Only comments added.

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada

kconfig: drop 'boolean' keyword

2018-01-21T15:49:29+00:00

No more users of this keyword.  Drop it according to the notice by
commit 6341e62b212a ("kconfig: use bool instead of boolean for type
definition attributes").

Signed-off-by: Masahiro Yamada 
Acked-by: Luis R. Rodriguez

kconfig: Remove menu_end_entry()

2018-01-21T15:49:28+00:00

menu_end_entry() is empty and completely unused as far as I can tell:

	$ git log -G menu_end_entry --oneline
	a02f057 [PATCH] kconfig: improve error handling in the parser
	1da177e Linux-2.6.12-rc2

Last one is the initial Git commit, where menu_end_entry() is empty as
well. I couldn't find anything that redefined it on Google either.

It might be a debugging helper for setting a breakpoint after each
config, menuconfig, and comment is parsed. IMO it hurts more than it
helps in that case by making the parsing code look more complicated at a
glance than it really is, and I suspect it doesn't get used much.

Tested by running the Kconfiglib test suite, which indirectly verifies
that the .config files generated by the C implementation for each
defconfig file in the kernel stays the same.

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada

kconfig: Document automatic submenu creation code

2018-01-21T15:49:28+00:00

It's tricky to figure out what it does (and how) without staring at the
code for a long time. Document it to make it more transparent.

No functional changes. Only comments added.

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada

kconfig: Fix choice symbol expression leak

2018-01-21T15:49:27+00:00

When propagating dependencies from parents after parsing, an expression
node is allocated if the parent symbol is a 'choice'. This node was
never freed.

Outline of leak:

	if (sym && sym_is_choice(sym)) {
		...
		*Allocate (in this case only)*
		parentdep = expr_alloc_symbol(sym);
	} else if (parent->prompt)
		parentdep = parent->prompt->visible.expr;
	else
		parentdep = parent->dep;

	for (menu = parent->list; menu; menu = menu->next) {
		...
		*Copy*
		basedep = expr_alloc_and(expr_copy(parentdep), basedep);
		...
	}
	*parentdep lost if the parent is a choice!*

Fix by freeing 'parentdep' after the loop if the parent symbol is a
choice. Note that this only frees the expression node and not the choice
symbol itself.

Summary from Valgrind on 'menuconfig' (ARCH=x86) before the fix:

	LEAK SUMMARY:
	   definitely lost: 1,608 bytes in 67 blocks
	   ...

Summary after the fix:

	LEAK SUMMARY:
	   definitely lost: 0 bytes in 0 blocks
	   ...

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada

kconfig: Fix automatic menu creation mem leak

2018-01-21T15:49:26+00:00

expr_trans_compare() always allocates and returns a new expression,
giving the following leak outline:

	...
	*Allocate*
	basedep = expr_trans_compare(basedep, E_UNEQUAL, &symbol_no);
	...
	for (menu = parent->next; menu; menu = menu->next) {
		...
		*Copy*
		dep2 = expr_copy(basedep);
		...
		*Free copy*
		expr_free(dep2);
	}
	*basedep lost!*

Fix by freeing 'basedep' after the loop.

Summary from Valgrind on 'menuconfig' (ARCH=x86) before the fix:

	LEAK SUMMARY:
	   definitely lost: 344,376 bytes in 14,349 blocks
	   ...

Summary after the fix:

	LEAK SUMMARY:
	   definitely lost: 44,448 bytes in 1,852 blocks
	   ...

Signed-off-by: Ulf Magnusson 
Signed-off-by: Masahiro Yamada