linux-kernel - [PATCH 4/4] module: Use the binary search for symbols resolution

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Message-Id: <1302960373-5309-5-git-send-email-abogani@kernel.org>
Date:	Sat, 16 Apr 2011 15:26:13 +0200
From:	Alessio Igor Bogani <abogani@...nel.org>
To:	Rusty Russell <rusty@...tcorp.com.au>,
	Tim Abbott <tabbott@...lice.com>,
	Anders Kaseorg <andersk@...lice.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	Tim Bird <tim.bird@...sony.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linux Embedded <linux-embedded@...r.kernel.org>,
	Alessio Igor Bogani <abogani@...nel.org>
Subject: [PATCH 4/4] module: Use the binary search for symbols resolution

Takes advantage of the order and locates symbols using binary search.

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

Signed-off-by: Alessio Igor Bogani <abogani@...nel.org>
---
 kernel/module.c |   23 ++++++++++++++++-------
 1 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index b438b25..74a57c1 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -57,6 +57,7 @@
 #include <linux/kmemleak.h>
 #include <linux/jump_label.h>
 #include <linux/pfn.h>
+#include <linux/bsearch.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/module.h>
@@ -351,22 +352,30 @@ struct find_symbol_arg {
 	const struct kernel_symbol *sym;
 };
 
+static int cmp_name(const void *va, const void *vb)
+{
+	const char *a;
+	const struct kernel_symbol *b;
+	a = va; b = vb;
+	return strcmp(a, b->name);
+}
+
 static bool find_symbol_in_symsearch(const struct symsearch *syms,
 				     struct module *owner,
 				     void *data)
 {
 	struct find_symbol_arg *fsa = data;
+	struct kernel_symbol *sym;
 	unsigned int symnum;
-	int result;
 
-	for (symnum = 0; symnum < syms->stop - syms->start; symnum++) {
-		result = strcmp(fsa->name, syms->start[symnum].name);
-		if (result == 0)
-			break;
-	}
-	if (symnum >= syms->stop - syms->start)
+	sym = bsearch(fsa->name, syms->start, syms->stop - syms->start,
+		sizeof(struct kernel_symbol), cmp_name);
+
+	if (sym == NULL)
 		return false;
 
+	symnum = sym - syms->start;
+
 	if (!fsa->gplok) {
 		if (syms->licence == GPL_ONLY)
 			return false;
-- 
1.7.4.1

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