linux-kernel - [PATCH v4 25/27] lib/bsearch: Provide __always

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Date:   Fri, 21 Feb 2020 14:34:41 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        rostedt@...dmis.org
Cc:     peterz@...radead.org, mingo@...nel.org, joel@...lfernandes.org,
        gregkh@...uxfoundation.org, gustavo@...eddedor.com,
        tglx@...utronix.de, paulmck@...nel.org, josh@...htriplett.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        luto@...nel.org, tony.luck@...el.com, frederic@...nel.org,
        dan.carpenter@...cle.com, mhiramat@...nel.org
Subject: [PATCH v4 25/27] lib/bsearch: Provide __always_inline variant

For code that needs the ultimate performance (it can inline the @cmp
function too) or simply needs to avoid calling external functions for
whatever reason, provide an __always_inline variant of bsearch().

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kernel/alternative.c |    9 ++++-----
 include/linux/bsearch.h       |   26 ++++++++++++++++++++++++--
 lib/bsearch.c                 |   22 ++--------------------
 3 files changed, 30 insertions(+), 27 deletions(-)

--- a/include/linux/bsearch.h
+++ b/include/linux/bsearch.h
@@ -4,7 +4,29 @@
 
 #include <linux/types.h>
 
-void *bsearch(const void *key, const void *base, size_t num, size_t size,
-	      cmp_func_t cmp);
+static __always_inline
+void *__bsearch(const void *key, const void *base, size_t num, size_t size, cmp_func_t cmp)
+{
+	const char *pivot;
+	int result;
+
+	while (num > 0) {
+		pivot = base + (num >> 1) * size;
+		result = cmp(key, pivot);
+
+		if (result == 0)
+			return (void *)pivot;
+
+		if (result > 0) {
+			base = pivot + size;
+			num--;
+		}
+		num >>= 1;
+	}
+
+	return NULL;
+}
+
+extern void *bsearch(const void *key, const void *base, size_t num, size_t size, cmp_func_t cmp);
 
 #endif /* _LINUX_BSEARCH_H */
--- a/lib/bsearch.c
+++ b/lib/bsearch.c
@@ -28,27 +28,9 @@
  * the key and elements in the array are of the same type, you can use
  * the same comparison function for both sort() and bsearch().
  */
-void *bsearch(const void *key, const void *base, size_t num, size_t size,
-	      cmp_func_t cmp)
+void *bsearch(const void *key, const void *base, size_t num, size_t size, cmp_func_t cmp)
 {
-	const char *pivot;
-	int result;
-
-	while (num > 0) {
-		pivot = base + (num >> 1) * size;
-		result = cmp(key, pivot);
-
-		if (result == 0)
-			return (void *)pivot;
-
-		if (result > 0) {
-			base = pivot + size;
-			num--;
-		}
-		num >>= 1;
-	}
-
-	return NULL;
+	return __bsearch(key, base, num, size, cmp);
 }
 EXPORT_SYMBOL(bsearch);
 NOKPROBE_SYMBOL(bsearch);