Commit-ID: 5a8aee6c809dc36e42b256566e5e28e244be3c74
Gitweb: http://git.kernel.org/tip/5a8aee6c809dc36e42b256566e5e28e244be3c74
Author: Subrata Modak <subrata@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 20 May 2009 11:51:15 +0530
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 17 Jun 2009 17:26:30 +0200
x86: Remove indirect variable usage at arch/x86/kernel/tsc.c
The following warning is generated on compilation:
CC arch/x86/kernel/tsc.o
arch/x86/kernel/tsc.c: In function 'time_cpufreq_notifier':
arch/x86/kernel/tsc.c:634: warning: 'dummy' may be used uninitialized in this function
However, there seems to be no practical usage of variable 'dummy'
in the following piece of code:
630 static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
631 void *data)
632 {
633 struct cpufreq_freqs *freq = data;
634 unsigned long *lpj, dummy;
635
636 if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
637 return 0;
638
639 lpj = &dummy;
640 if (!(freq->flags & CPUFREQ_CONST_LOOPS))
641 #ifdef CONFIG_SMP
642 lpj = &cpu_data(freq->cpu).loops_per_jiffy;
643 #else
644 lpj = &boot_cpu_data.loops_per_jiffy;
645 #endif
646
'lpj' probably will get to point to some address after this if() statement.
647 if (!ref_freq) {
648 ref_freq = freq->old;
649 loops_per_jiffy_ref = *lpj;
And, if it does, then "loops_per_jiffy_ref" will have a proper value,
else, even with "lpj = &dummy" will not gurantee "loops_per_jiffy_ref = *lpj"
to have the expected value.
650 tsc_khz_ref = tsc_khz;
651 }
652 if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
653 (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
654 (val == CPUFREQ_RESUMECHANGE)) {
655 *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
656
657 tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
658 if (!(freq->flags & CPUFREQ_CONST_LOOPS))
659 mark_tsc_unstable("cpufreq changes");
660 }
661
662 set_cyc2ns_scale(tsc_khz, freq->cpu);
663
664 return 0;
665 }
Also included fix expected by Frans Pop:
> No comments on your patch, but it might be good to also fix the incorrect
> indentation here: line 644 needs an extra tab.
Please refer:
http://lkml.org/lkml/2009/5/19/312, and,
http://lkml.org/lkml/2009/5/19/301.
Signed-off-by: Subrata Modak <subrata@xxxxxxxxxxxxxxxxxx>
Cc: Sachin P Sant <sachinp@xxxxxxxxxxxxxxxxxx>
Cc: Frans Pop <elendil@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <20090520062115.23889.45487.sendpatchset@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/kernel/tsc.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 3e1c057..7714609 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -631,17 +631,16 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
void *data)
{
struct cpufreq_freqs *freq = data;
- unsigned long *lpj, dummy;
+ unsigned long *lpj = NULL;
if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
return 0;
- lpj = &dummy;
if (!(freq->flags & CPUFREQ_CONST_LOOPS))
#ifdef CONFIG_SMP
lpj = &cpu_data(freq->cpu).loops_per_jiffy;
#else
- lpj = &boot_cpu_data.loops_per_jiffy;
+ lpj = &boot_cpu_data.loops_per_jiffy;
#endif
if (!ref_freq) {
@@ -652,7 +651,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
(val == CPUFREQ_RESUMECHANGE)) {
- *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
+ *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
if (!(freq->flags & CPUFREQ_CONST_LOOPS))
--
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