From: Jim Cromie jim.cromie@gmail.com
[ Upstream commit 85d6b66d31c35158364058ee98fb69ab5bb6a6b1 ]
For CONFIG_DYNAMIC_DEBUG=N, the ddebug_dyndbg_module_param_cb() stub-fn is too permissive:
bash-5.1# modprobe drm JUNKdyndbg bash-5.1# modprobe drm dyndbgJUNK [ 42.933220] dyndbg param is supported only in CONFIG_DYNAMIC_DEBUG builds [ 42.937484] ACPI: bus type drm_connector registered
This caused no ill effects, because unknown parameters are either ignored by default with an "unknown parameter" warning, or ignored because dyndbg allows its no-effect use on non-dyndbg builds.
But since the code has an explicit feedback message, it should be issued accurately. Fix with strcmp for exact param-name match.
Fixes: b48420c1d301 dynamic_debug: make dynamic-debug work for module initialization Reported-by: Rasmus Villemoes linux@rasmusvillemoes.dk Acked-by: Jason Baron jbaron@akamai.com Acked-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Jim Cromie jim.cromie@gmail.com Link: https://lore.kernel.org/r/20220904214134.408619-3-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/dynamic_debug.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index dce631e678dd..f30b01aa9fa4 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -201,7 +201,7 @@ static inline int ddebug_remove_module(const char *mod) static inline int ddebug_dyndbg_module_param_cb(char *param, char *val, const char *modname) { - if (strstr(param, "dyndbg")) { + if (!strcmp(param, "dyndbg")) { /* avoid pr_warn(), which wants pr_fmt() fully defined */ printk(KERN_WARNING "dyndbg param is supported only in " "CONFIG_DYNAMIC_DEBUG builds\n");