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Subject[PATCH v4 06/14] dynamic_debug: use pointer comparison in ddebug_remove_module
Date
Now that we store the passed-in string directly in ddebug_add_module, we
can use pointer equality instead of strcmp. This is a little more
efficient, but more importantly, this also makes the code somewhat more
correct:

Currently, if one loads and then unloads a module whose name happens to
match the KBUILD_MODNAME of some built-in functionality (which need not
even be modular at all), all of their dynamic debug entries vanish along
with those of the actual module. For example, loading and unloading a
core.ko hides all pr_debugs from drivers/base/core.c and other built-in
files called core.c (incidentally, there is an in-tree module whose name
is core, but I just tested this with an out-of-tree trivial one).

Acked-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
lib/dynamic_debug.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8274c4ea75e0..214828c65625 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -929,9 +929,10 @@ int ddebug_remove_module(const char *mod_name)

mutex_lock(&ddebug_lock);
list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
- if (!strcmp(dt->mod_name, mod_name)) {
+ if (dt->mod_name == mod_name) {
ddebug_table_free(dt);
ret = 0;
+ break;
}
}
mutex_unlock(&ddebug_lock);
--
2.20.1
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