linux-kernel - [tip: x86/cleanups] x86/mm: Declare 'start' variable where it is used

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Message-ID: <160587310720.11244.17157588656599003783.tip-bot2@tip-bot2>
Date:   Fri, 20 Nov 2020 11:51:47 -0000
From:   "tip-bot2 for Lukas Bulwahn" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Borislav Petkov <bp@...e.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/cleanups] x86/mm: Declare 'start' variable where it is used

The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID:     bab202ab87ba4da48018daf0f6810b22705a570d
Gitweb:        https://git.kernel.org/tip/bab202ab87ba4da48018daf0f6810b22705a570d
Author:        Lukas Bulwahn <lukas.bulwahn@...il.com>
AuthorDate:    Mon, 28 Sep 2020 12:00:04 +02:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Fri, 20 Nov 2020 12:49:00 +01:00

x86/mm: Declare 'start' variable where it is used

It is not required to initialize the local variable start in
memory_map_top_down(), as the variable will be initialized in any path
before it is used.

make clang-analyzer on x86_64 tinyconfig reports:

  arch/x86/mm/init.c:612:15: warning: Although the value stored to 'start' \
  is used in the enclosing expression, the value is never actually read \
  from 'start' [clang-analyzer-deadcode.DeadStores]

Move the variable declaration into the loop, where it is used.

No code changed:

  # arch/x86/mm/init.o:

   text    data     bss     dec     hex filename
   7105    1424   26768   35297    89e1 init.o.before
   7105    1424   26768   35297    89e1 init.o.after

md5:
   a8d76c1bb5fce9cae251780a7ee7730f  init.o.before.asm
   a8d76c1bb5fce9cae251780a7ee7730f  init.o.after.asm

 [ bp: Massage. ]

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Link: https://lkml.kernel.org/r/20200928100004.25674-1-lukas.bulwahn@gmail.com
---
 arch/x86/mm/init.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index c7a4760..e26f5c5 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -596,7 +596,7 @@ static unsigned long __init get_new_step_size(unsigned long step_size)
 static void __init memory_map_top_down(unsigned long map_start,
 				       unsigned long map_end)
 {
-	unsigned long real_end, start, last_start;
+	unsigned long real_end, last_start;
 	unsigned long step_size;
 	unsigned long addr;
 	unsigned long mapped_ram_size = 0;
@@ -609,7 +609,7 @@ static void __init memory_map_top_down(unsigned long map_start,
 	step_size = PMD_SIZE;
 	max_pfn_mapped = 0; /* will get exact value next */
 	min_pfn_mapped = real_end >> PAGE_SHIFT;
-	last_start = start = real_end;
+	last_start = real_end;
 
 	/*
 	 * We start from the top (end of memory) and go to the bottom.
@@ -618,6 +618,8 @@ static void __init memory_map_top_down(unsigned long map_start,
 	 * for page table.
 	 */
 	while (last_start > map_start) {
+		unsigned long start;
+
 		if (last_start > step_size) {
 			start = round_down(last_start - 1, step_size);
 			if (start < map_start)