module: Use binary search in lookup_symbol()

The function is_exported() with its helper function lookup_symbol() are used to
verify if a provided symbol is effectively exported by the kernel or by the
modules. Now that both have their symbols sorted we can replace a linear search
with a binary search which provide a considerably speed-up.

This work was supported by a hardware donation from the CE Linux Forum.

Signed-off-by: Alessio Igor Bogani <abogani@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/kernel/module.c b/kernel/module.c
index d1db8eb56ad41c247b0213e5d551658b3654b6e9..22879725678dfcd53324698504500dc97decdea6 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2055,11 +2055,8 @@ static const struct kernel_symbol *lookup_symbol(const char *name,
        const struct kernel_symbol *start,
        const struct kernel_symbol *stop)
 {
-       const struct kernel_symbol *ks = start;
-       for (; ks < stop; ks++)
-               if (strcmp(ks->name, name) == 0)
-                       return ks;
-       return NULL;
+       return bsearch(name, start, stop - start,
+                       sizeof(struct kernel_symbol), cmp_name);
 }
 
 static int is_exported(const char *name, unsigned long value,