Hi Arnaud,
On Sun, 2010-09-19 at 22:54 -0400, Arnaud Lacombe wrote:
> It would seem that this issue is responsible for the crash I've seen
> randomly happening with gconf (2.6.36-rc6, before my generalization's
> branch). So far, I've traced it to the following line in
> menu_finalize():
>
> sym->dir_dep.expr = expr_transform(expr_copy(parent->dir_dep));
>
> The crash happen in expr_copy(). expr_transform() is never being
> called. The trace is the following:
>
> Program received signal SIGSEGV, Segmentation fault.
[...]
> so we're dying from stack exhaustion, because expr_copy() is given a
> really nasty symbol:
[...]
> Reverting 246cf9c26bf11f2bffbecea6e5bd222eee7b1df8 fixes the crash.
Thanks for investigating this. The expr_copy() is a recursive function
and it could indeed run out of stack.
I wonder if we really need the expr_copy() here. It looks to me like
expr_transform() already does some memory allocations:
kbuild: Avoid additional copy of the 'depends' expression
From: Catalin Marinas <catalin.marinas@xxxxxxx>
Commit 246cf9c26b introduced the tracking of direct dependency to
provide additional warning when they are not met. With some complex
dependencies, the expr_copy() function called on such expressions may
cause stack exhaustion. The patch removes the superfluous expr_copy()
call since expr_transform handles symbol duplication already.
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Reported-by: Arnaud Lacombe <lacombar@xxxxxxxxx>
---
scripts/kconfig/menu.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 4fb5902..7298806 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -292,7 +292,7 @@ void menu_finalize(struct menu *parent)
menu_finalize(menu);
} else if (sym) {
/* ignore inherited dependencies for dir_dep */
- sym->dir_dep.expr = expr_transform(expr_copy(parent->dir_dep));
+ sym->dir_dep.expr = expr_transform(parent->dir_dep);
sym->dir_dep.expr = expr_eliminate_dups(sym->dir_dep.expr);
basedep = parent->prompt ? parent->prompt->visible.expr : NULL;
--
Catalin
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