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lib: hashtable: Prevent recursive calling of callback functions

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In case there are two variables which each implement env callback
that performs env_set() on the other variable, the callbacks will
call each other recursively until the stack runs out. Prevent such
a recursion from happening.

Example which triggers this behavior:
static int on_foo(...) { env_set("bar", 0); ... }
static int on_bar(...) { env_set("foo", 0); ... }
U_BOOT_ENV_CALLBACK(foo, on_foo);
U_BOOT_ENV_CALLBACK(bar, on_bar);

Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Suggested-by: Marek Vasut <marex@denx.de>
This commit is contained in:
Christoph Niedermaier 2024-12-07 00:04:19 +01:00 • committed by Fabio Estevam
parent 489b965564
commit 86f58ea539
1 changed files with 24 additions and 3 deletions
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27
lib/hashtable.c
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@ -221,11 +221,32 @@ static int
do_callback(const struct env_entry *e, const char *name, const char *value,
enum env_op op, int flags)
{
int ret = 0;
#ifndef CONFIG_XPL_BUILD
if (e->callback)
return e->callback(name, value, op, flags);
static bool in_callback;
if (!e->callback || in_callback)
return 0;
/*
* In case there are two variables which each implement env callback
* that performs env_set() on the other variable, the callbacks will
* call each other recursively until the stack runs out. Prevent such
* a recursion from happening.
*
* Example which triggers this behavior:
* static int on_foo(...) { env_set("bar", 0); ... }
* static int on_bar(...) { env_set("foo", 0); ... }
* U_BOOT_ENV_CALLBACK(foo, on_foo);
* U_BOOT_ENV_CALLBACK(bar, on_bar);
*/
in_callback = true;
ret = e->callback(name, value, op, flags);
in_callback = false;
#endif
return 0;
return ret;
}
/*