linux-kernel - [PATCH 3.16 42/76] x86/cpu: Change type of x86_cache

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Date:   Mon, 12 Mar 2018 03:06:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Borislav Petkov" <bp@...en8.de>, "Ingo Molnar" <mingo@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Peter Zijlstra" <peterz@...radead.org>
Subject: [PATCH 3.16 42/76] x86/cpu: Change type of x86_cache_size
 variable to unsigned int

3.16.56-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Gustavo A. R. Silva" <garsilva@...eddedor.com>

commit 24dbc6000f4b9b0ef5a9daecb161f1907733765a upstream.

Currently, x86_cache_size is of type int, which makes no sense as we
will never have a valid cache size equal or less than 0. So instead of
initializing this variable to -1, it can perfectly be initialized to 0
and use it as an unsigned variable instead.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Addresses-Coverity-ID: 1464429
Link: http://lkml.kernel.org/r/20180213192208.GA26414@embeddedor.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/include/asm/processor.h      | 2 +-
 arch/x86/kernel/cpu/common.c          | 2 +-
 arch/x86/kernel/cpu/microcode/intel.c | 2 +-
 arch/x86/kernel/cpu/proc.c            | 4 ++--
 4 files changed, 5 insertions(+), 5 deletions(-)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -107,7 +107,7 @@ struct cpuinfo_x86 {
 	char			x86_vendor_id[16];
 	char			x86_model_id[64];
 	/* in KB - valid for CPUS which support this call: */
-	int			x86_cache_size;
+	unsigned int		x86_cache_size;
 	int			x86_cache_alignment;	/* In bytes */
 	int			x86_power;
 	unsigned long		loops_per_jiffy;
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -905,7 +905,7 @@ static void identify_cpu(struct cpuinfo_
 	int i;
 
 	c->loops_per_jiffy = loops_per_jiffy;
-	c->x86_cache_size = -1;
+	c->x86_cache_size = 0;
 	c->x86_vendor = X86_VENDOR_UNKNOWN;
 	c->x86_model = c->x86_mask = 0;	/* So far unknown... */
 	c->x86_vendor_id[0] = '\0'; /* Unset */
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -352,7 +352,7 @@ static struct microcode_ops microcode_in
 
 static int __init calc_llc_size_per_core(struct cpuinfo_x86 *c)
 {
-	u64 llc_size = c->x86_cache_size * 1024;
+	u64 llc_size = c->x86_cache_size * 1024ULL;
 
 	do_div(llc_size, c->x86_max_cores);
 
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -86,8 +86,8 @@ static int show_cpuinfo(struct seq_file
 	}
 
 	/* Cache size */
-	if (c->x86_cache_size >= 0)
-		seq_printf(m, "cache size\t: %d KB\n", c->x86_cache_size);
+	if (c->x86_cache_size)
+		seq_printf(m, "cache size\t: %u KB\n", c->x86_cache_size);
 
 	show_cpuinfo_core(m, c, cpu);
 	show_cpuinfo_misc(m, c);