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SubjectRe: [PATCH] kconfig: fix missing choice values in auto.conf
Hello,

> conf_write() must be changed accordingly. Currently, it clears
> SYMBOL_WRITE after the symbol is written into the .config file. This
> is needed to prevent it from writing the same symbol multiple times in
> case the symbol is declared in two or more locations. I added the new
> flag SYMBOL_WRITTEN, to track the symbols that have been written.
[snip]
> diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
> index cbb6efa4a5a6..e0972b255aac 100644
> --- a/scripts/kconfig/confdata.c
> +++ b/scripts/kconfig/confdata.c
[snip]
> @@ -903,7 +904,7 @@ int conf_write(const char *name)
> fprintf(out, "\n");
> need_newline = false;
> }
> - sym->flags &= ~SYMBOL_WRITE;
> + sym->flags |= SYMBOL_WRITTEN;

The SYMBOL_WRITTEN flag is never cleared after being set in this
function, which unfortunately causes data loss to occur when a user
starts xconfig, gconfig, or nconfig and saves a config file more than
once. Every save operation after the first one causes the saved .config
file to contain only comments.

I am appending a patch that resolves this issue. The patch is a bit
ugly because of the code duplication, but it fixes this bug. (I have
lightly tested the patch.) Even if the patch is not merged, I would
appreciate it if this bug could be fixed.

Thank you,

Vefa

=== 8< === Patch Follows === >8 ===

From: "M. Vefa Bicakci" <m.v.b@runbox.com>
Date: Fri, 2 Aug 2019 17:44:40 -0400
Subject: [PATCH] kconfig: Clear "written" flag to avoid data loss

Prior to this commit, starting nconfig, xconfig or gconfig, and saving
the .config file more than once caused data loss, where a .config file
that contained only comments would be written to disk starting from the
second save operation.

This bug manifests itself because the SYMBOL_WRITTEN flag is never
cleared after the first call to conf_write, and subsequent calls to
conf_write then skip all of the configuration symbols due to the
SYMBOL_WRITTEN flag being set.

This commit resolves this issue by clearing the SYMBOL_WRITTEN flag
from all symbols before conf_write returns.

Fixes: 8e2442a5f86e ("kconfig: fix missing choice values in auto.conf")
Cc: linux-stable <stable@vger.kernel.org> # 4.19+
Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
---
scripts/kconfig/confdata.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 1134892599da..24fe0c851e8c 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -840,6 +840,35 @@ int conf_write_defconfig(const char *filename)
return 0;
}

+static void conf_clear_written_flag(void)
+{
+ struct menu *menu;
+ struct symbol *sym;
+
+ menu = rootmenu.list;
+ while (menu) {
+ sym = menu->sym;
+ if (sym && (sym->flags & SYMBOL_WRITTEN))
+ sym->flags &= ~SYMBOL_WRITTEN;
+
+ if (menu->list) {
+ menu = menu->list;
+ continue;
+ }
+
+ if (menu->next) {
+ menu = menu->next;
+ } else {
+ while ((menu = menu->parent)) {
+ if (menu->next) {
+ menu = menu->next;
+ break;
+ }
+ }
+ }
+ }
+}
+
int conf_write(const char *name)
{
FILE *out;
@@ -930,6 +959,8 @@ int conf_write(const char *name)
}
fclose(out);

+ conf_clear_written_flag();
+
if (*tmpname) {
if (is_same(name, tmpname)) {
conf_message("No change to %s", name);
--
2.21.0
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