[PATCH v3 4/5] module: Account for the build time module name mangling

[Peter Zijlstra]

Sean noted that scripts/Makefile.lib:name-fix-token rule will mangle
the module name with s/-/_/g.

Since this happens late in the build, only the kernel needs to bother
with this, the modpost tool still sees the original name.

Reported-by: Sean Christopherson <sea...@google.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Tested-by: Sean Christopherson <sea...@google.com>
---
 kernel/module/main.c |   26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -170,6 +170,30 @@ static inline void add_taint_module(stru
 }
 
 /*
+ * Like strncmp(), except s/-/_/g as per scripts/Makefile.lib:name-fix-token 
rule.
+ */
+static int mod_strncmp(const char *str_a, const char *str_b, size_t n)
+{
+       for (int i = 0; i < n; i++) {
+               char a = str_a[i];
+               char b = str_b[i];
+               int d;
+
+               if (a == '-') a = '_';
+               if (b == '-') b = '_';
+
+               d = a - b;
+               if (d)
+                       return d;
+
+               if (!a)
+                       break;
+       }
+
+       return 0;
+}
+
+/*
  * A thread that wants to hold a reference to a module only while it
  * is running can call this to safely exit.
  */
@@ -1116,7 +1140,7 @@ static bool verify_module_namespace(cons
                if (*sep)
                        sep++;
 
-               if (strncmp(namespace, modname, len) == 0 && (glob || len == 
modlen))
+               if (mod_strncmp(namespace, modname, len) == 0 && (glob || len 
== modlen))
                        return true;
        }