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* [PATCH] x86: boot: Simplified memory.c
@ 2018-11-02 14:56 Jordan Borgner
  2018-11-07  8:07 ` [tip:x86/boot] x86/boot: Simplify the detect_memory*() control flow tip-bot for Jordan Borgner
  0 siblings, 1 reply; 2+ messages in thread
From: Jordan Borgner @ 2018-11-02 14:56 UTC (permalink / raw)
  To: tglx, mingo, x86; +Cc: hpa, linux-kernel

[-- Attachment #1: 0002-x86-boot-Simplified-memory.c.patch --]
[-- Type: text/x-diff, Size: 2802 bytes --]

memory.c contains functions that retrieve the memory-map of the
available RAM.

They are all called inside of "detect_memory()" which is 
called in x86/boot/main.c. The return value of "detect_memory()" is 
not checked so none of all the return values have any effect 
on the program flow.

Define them as void-functions to save overhead.

Done by motivation of Ingo Molnar.

Signed-off-by: Jordan Borgner <mail@jordan-borgner.de>
---
 arch/x86/boot/boot.h   |  2 +-
 arch/x86/boot/memory.c | 31 ++++++++++---------------------
 2 files changed, 11 insertions(+), 22 deletions(-)

diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index ef5a9cc..32a09eb 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -309,7 +309,7 @@ void query_edd(void);
 void __attribute__((noreturn)) die(void);

 /* memory.c */
-int detect_memory(void);
+void detect_memory(void);

 /* pm.c */
 void __attribute__((noreturn)) go_to_protected_mode(void);
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c
index 7df2b28..f06c147 100644
--- a/arch/x86/boot/memory.c
+++ b/arch/x86/boot/memory.c
@@ -17,7 +17,7 @@
 
 #define SMAP	0x534d4150	/* ASCII "SMAP" */
 
-static int detect_memory_e820(void)
+static void detect_memory_e820(void)
 {
 	int count = 0;
 	struct biosregs ireg, oreg;
@@ -68,10 +68,10 @@ static int detect_memory_e820(void)
 		count++;
 	} while (ireg.ebx && count < ARRAY_SIZE(boot_params.e820_table));
 
-	return boot_params.e820_entries = count;
+	boot_params.e820_entries = count;
 }
 
-static int detect_memory_e801(void)
+static void detect_memory_e801(void)
 {
 	struct biosregs ireg, oreg;
 
@@ -80,7 +80,7 @@ static int detect_memory_e801(void)
 	intcall(0x15, &ireg, &oreg);
 
 	if (oreg.eflags & X86_EFLAGS_CF)
-		return -1;
+		return;
 
 	/* Do we really need to do this? */
 	if (oreg.cx || oreg.dx) {
@@ -89,7 +89,7 @@ static int detect_memory_e801(void)
 	}
 
 	if (oreg.ax > 15*1024) {
-		return -1;	/* Bogus! */
+		return;	/* Bogus! */
 	} else if (oreg.ax == 15*1024) {
 		boot_params.alt_mem_k = (oreg.bx << 6) + oreg.ax;
 	} else {
@@ -102,11 +102,9 @@ static int detect_memory_e801(void)
 		 */
 		boot_params.alt_mem_k = oreg.ax;
 	}
-
-	return 0;
 }
 
-static int detect_memory_88(void)
+static void detect_memory_88(void)
 {
 	struct biosregs ireg, oreg;
 
@@ -115,22 +113,13 @@ static int detect_memory_88(void)
 	intcall(0x15, &ireg, &oreg);
 
 	boot_params.screen_info.ext_mem_k = oreg.ax;
-
-	return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */
 }
 
-int detect_memory(void)
+void detect_memory(void)
 {
-	int err = -1;
-
-	if (detect_memory_e820() > 0)
-		err = 0;
-
-	if (!detect_memory_e801())
-		err = 0;
+	detect_memory_e820();
 
-	if (!detect_memory_88())
-		err = 0;
+	detect_memory_e801();
 
-	return err;
+	detect_memory_88();
 }
-- 
2.11.0


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2018-11-02 14:56 [PATCH] x86: boot: Simplified memory.c Jordan Borgner
2018-11-07  8:07 ` [tip:x86/boot] x86/boot: Simplify the detect_memory*() control flow tip-bot for Jordan Borgner

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