kernel/kmod.c: document call_usermodehelper_fns() a bit

This function's interface is, uh, subtle.  Attempt to apologise for it.

Cc: WANG Cong <[email protected]>
Cc: Cyrill Gorcunov <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Serge Hallyn <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Alan Cox <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Rusty Russell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/kernel/kmod.c b/kernel/kmod.c
index ff2c7cb86d770aaf51712e330dc0f1e8a72a26e6..2a8351516a0ea875a0ca062e149a76bfa9682396 100644 (file)
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -577,6 +577,12 @@ unlock:
        return retval;
 }
 
+/*
+ * call_usermodehelper_fns() will not run the caller-provided cleanup function
+ * if a memory allocation failure is experienced.  So the caller might need to
+ * check the call_usermodehelper_fns() return value: if it is -ENOMEM, perform
+ * the necessaary cleanup within the caller.
+ */
 int call_usermodehelper_fns(
        char *path, char **argv, char **envp, int wait,
        int (*init)(struct subprocess_info *info, struct cred *new),