[PATCH] x86/smp: Unused value freq_scale

[PATCH] x86/smp: Unused value freq_scale

[Tim Gardner]

Coverity warns of an unused value in arch_scale_freq_tick().

CID 100778 (#1 of 1): Unused value (UNUSED_VALUE)
assigned_value: Assigning value 1024ULL to freq_scale here, but that stored
value is overwritten before it can be used.

e2b0d619b400a ("x86, sched: check for counters overflow in frequency invariant
accounting") introduced this warning.

Fix this by removing the variable initializer.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Nathan Fontenot <nathan.fontenot@amd.com>
Cc: Balbir Singh <sblbir@amazon.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
 arch/x86/kernel/smpboot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 85f6e242b6b4..c453b825a57f 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -2166,7 +2166,7 @@ DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE;
 
 void arch_scale_freq_tick(void)
 {
-	u64 freq_scale = SCHED_CAPACITY_SCALE;
+	u64 freq_scale;
 	u64 aperf, mperf;
 	u64 acnt, mcnt;
 
-- 
2.33.0

Re: [PATCH] x86/smp: Unused value freq_scale

[Giovanni Gherdovich]

On Fri, 2021-09-10 at 12:44 -0600, Tim Gardner wrote:
> Coverity warns of an unused value in arch_scale_freq_tick().
> 
> CID 100778 (#1 of 1): Unused value (UNUSED_VALUE)
> assigned_value: Assigning value 1024ULL to freq_scale here, but that stored
> value is overwritten before it can be used.
> 
> e2b0d619b400a ("x86, sched: check for counters overflow in frequency invariant
> accounting") introduced this warning.
> 
> Fix this by removing the variable initializer.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: x86@kernel.org
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
> Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Alison Schofield <alison.schofield@intel.com>
> Cc: Nathan Fontenot <nathan.fontenot@amd.com>
> Cc: Balbir Singh <sblbir@amazon.com>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
> ---
>  arch/x86/kernel/smpboot.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 85f6e242b6b4..c453b825a57f 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -2166,7 +2166,7 @@ DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE;
>  
>  void arch_scale_freq_tick(void)
>  {
> -	u64 freq_scale = SCHED_CAPACITY_SCALE;
> +	u64 freq_scale;
>  	u64 aperf, mperf;
>  	u64 acnt, mcnt;
>  

Reviewed-by: Giovanni Gherdovich <ggherdovich@suse.cz>


Thanks,
Giovanni

[tip: x86/cleanups] x86/smp: Remove unnecessary assignment to local var freq_scale

[tip-bot2 for Tim Gardner]

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

Commit-ID:     85784470efa2d5733e86679ba05d310ece81b20f
Gitweb:        https://git.kernel.org/tip/85784470efa2d5733e86679ba05d310ece81b20f
Author:        Tim Gardner <tim.gardner@canonical.com>
AuthorDate:    Fri, 10 Sep 2021 12:44:05 -06:00
Committer:     Borislav Petkov <bp@suse.de>
CommitterDate: Fri, 17 Sep 2021 21:20:34 +02:00

x86/smp: Remove unnecessary assignment to local var freq_scale

Coverity warns of an unused value in arch_scale_freq_tick():

  CID 100778 (#1 of 1): Unused value (UNUSED_VALUE)
  assigned_value: Assigning value 1024ULL to freq_scale here, but that stored
  value is overwritten before it can be used.

It was introduced by commit:

  e2b0d619b400a ("x86, sched: check for counters overflow in frequency invariant accounting")

Remove the variable initializer.

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Link: https://lkml.kernel.org/r/20210910184405.24422-1-tim.gardner@canonical.com
---
 arch/x86/kernel/smpboot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 85f6e24..c453b82 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -2166,7 +2166,7 @@ DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE;
 
 void arch_scale_freq_tick(void)
 {
-	u64 freq_scale = SCHED_CAPACITY_SCALE;
+	u64 freq_scale;
 	u64 aperf, mperf;
 	u64 acnt, mcnt;