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Subject[tip:perf/core] perf/x86/intel/pt: Clean up the control flow in pt_pmu_hw_init()
Commit-ID:  066450be419fa48007a9f29e19828f2a86198754
Gitweb: http://git.kernel.org/tip/066450be419fa48007a9f29e19828f2a86198754
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Sun, 12 Apr 2015 11:11:21 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 12 Apr 2015 11:21:15 +0200

perf/x86/intel/pt: Clean up the control flow in pt_pmu_hw_init()

Dan Carpenter pointed out that the control flow in pt_pmu_hw_init()
is a bit messy: for example the kfree(de_attrs) is entirely
superfluous.

Another problem is the inconsistent mixing of label based and
direct return error handling.

Add modern, label based error handling instead and clean up the code
a bit as well.

Note that we'll still do a kfree(NULL) in the normal case - this does
not matter as this is an init path and kfree() returns early if it
sees a NULL.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20150409090805.GG17605@mwanda
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/cpu/perf_event_intel_pt.c | 53 +++++++++++++++++--------------
1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c
index f5a3afc..f277064 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
@@ -119,48 +119,55 @@ static int __init pt_pmu_hw_init(void)
struct dev_ext_attribute *de_attrs;
struct attribute **attrs;
size_t size;
+ int ret;
long i;

- if (test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT)) {
- for (i = 0; i < PT_CPUID_LEAVES; i++)
- cpuid_count(20, i,
- &pt_pmu.caps[CR_EAX + i * 4],
- &pt_pmu.caps[CR_EBX + i * 4],
- &pt_pmu.caps[CR_ECX + i * 4],
- &pt_pmu.caps[CR_EDX + i * 4]);
- } else {
- return -ENODEV;
+ attrs = NULL;
+ ret = -ENODEV;
+ if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT))
+ goto fail;
+
+ for (i = 0; i < PT_CPUID_LEAVES; i++) {
+ cpuid_count(20, i,
+ &pt_pmu.caps[CR_EAX + i*4],
+ &pt_pmu.caps[CR_EBX + i*4],
+ &pt_pmu.caps[CR_ECX + i*4],
+ &pt_pmu.caps[CR_EDX + i*4]);
}

- size = sizeof(struct attribute *) * (ARRAY_SIZE(pt_caps) + 1);
+ ret = -ENOMEM;
+ size = sizeof(struct attribute *) * (ARRAY_SIZE(pt_caps)+1);
attrs = kzalloc(size, GFP_KERNEL);
if (!attrs)
- goto err_attrs;
+ goto fail;

- size = sizeof(struct dev_ext_attribute) * (ARRAY_SIZE(pt_caps) + 1);
+ size = sizeof(struct dev_ext_attribute) * (ARRAY_SIZE(pt_caps)+1);
de_attrs = kzalloc(size, GFP_KERNEL);
if (!de_attrs)
- goto err_de_attrs;
+ goto fail;

for (i = 0; i < ARRAY_SIZE(pt_caps); i++) {
- de_attrs[i].attr.attr.name = pt_caps[i].name;
+ struct dev_ext_attribute *de_attr = de_attrs + i;
+
+ de_attr->attr.attr.name = pt_caps[i].name;
+
+ sysfs_attr_init(&de_attrs->attr.attr);

- sysfs_attr_init(&de_attrs[i].attr.attr);
- de_attrs[i].attr.attr.mode = S_IRUGO;
- de_attrs[i].attr.show = pt_cap_show;
- de_attrs[i].var = (void *)i;
- attrs[i] = &de_attrs[i].attr.attr;
+ de_attr->attr.attr.mode = S_IRUGO;
+ de_attr->attr.show = pt_cap_show;
+ de_attr->var = (void *)i;
+
+ attrs[i] = &de_attr->attr.attr;
}

pt_cap_group.attrs = attrs;
+
return 0;

-err_de_attrs:
- kfree(de_attrs);
-err_attrs:
+fail:
kfree(attrs);

- return -ENOMEM;
+ return ret;
}

#define PT_CONFIG_MASK (RTIT_CTL_TSC_EN | RTIT_CTL_DISRETC)

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