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>

1 files 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 f5a3afc65371..f2770641c0fd 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)