[XEN PATCH 2/2] xen/cpu: address MISRA C Rule 17.7

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

Refactor cpu_notifier_call_chain into two functions:
- the variant that is allowed to fail loses the nofail flag
- the variant that shouldn't fail is encapsulated in a call
  to the failing variant, with an additional check.

This prevents uses of the function that are not supposed to
fail from ignoring the return value, thus violating Rule 17.7:
"The value returned by a function having non-void return type shall
be used".

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
---
 xen/common/cpu.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/xen/common/cpu.c b/xen/common/cpu.c
index 8709db4d2957..0b7cf54c4264 100644
--- a/xen/common/cpu.c
+++ b/xen/common/cpu.c
@@ -78,20 +78,27 @@ void __init register_cpu_notifier(struct notifier_block *nb)
 }
 
 static int cpu_notifier_call_chain(unsigned int cpu, unsigned long action,
-                                   struct notifier_block **nb, bool nofail)
+                                   struct notifier_block **nb)
 {
     void *hcpu = (void *)(long)cpu;
     int notifier_rc = notifier_call_chain(&cpu_chain, action, hcpu, nb);
     int ret =  notifier_to_errno(notifier_rc);
 
-    BUG_ON(ret && nofail);
-
     return ret;
 }
 
+static void cpu_notifier_call_chain_nofail(unsigned int cpu,
+                                           unsigned long action,
+                                           struct notifier_block **nb)
+{
+    int ret = cpu_notifier_call_chain(cpu, action, nb);
+
+    BUG_ON(ret);
+}
+
 static void cf_check _take_cpu_down(void *unused)
 {
-    cpu_notifier_call_chain(smp_processor_id(), CPU_DYING, NULL, true);
+    cpu_notifier_call_chain_nofail(smp_processor_id(), CPU_DYING, NULL);
     __cpu_disable();
 }
 
@@ -116,7 +123,7 @@ int cpu_down(unsigned int cpu)
     if ( !cpu_online(cpu) )
         goto out;
 
-    err = cpu_notifier_call_chain(cpu, CPU_DOWN_PREPARE, &nb, false);
+    err = cpu_notifier_call_chain(cpu, CPU_DOWN_PREPARE, &nb);
     if ( err )
         goto fail;
 
@@ -129,14 +136,14 @@ int cpu_down(unsigned int cpu)
     err = cpu_online(cpu);
     BUG_ON(err);
 
-    cpu_notifier_call_chain(cpu, CPU_DEAD, NULL, true);
+    cpu_notifier_call_chain_nofail(cpu, CPU_DEAD, NULL);
 
     send_global_virq(VIRQ_PCPU_STATE);
     cpu_hotplug_done();
     return 0;
 
  fail:
-    cpu_notifier_call_chain(cpu, CPU_DOWN_FAILED, &nb, true);
+    cpu_notifier_call_chain_nofail(cpu, CPU_DOWN_FAILED, &nb);
  out:
     cpu_hotplug_done();
     return err;
@@ -157,7 +164,7 @@ int cpu_up(unsigned int cpu)
     if ( cpu_online(cpu) )
         goto out;
 
-    err = cpu_notifier_call_chain(cpu, CPU_UP_PREPARE, &nb, false);
+    err = cpu_notifier_call_chain(cpu, CPU_UP_PREPARE, &nb);
     if ( err )
         goto fail;
 
@@ -165,7 +172,7 @@ int cpu_up(unsigned int cpu)
     if ( err < 0 )
         goto fail;
 
-    cpu_notifier_call_chain(cpu, CPU_ONLINE, NULL, true);
+    cpu_notifier_call_chain_nofail(cpu, CPU_ONLINE, NULL);
 
     send_global_virq(VIRQ_PCPU_STATE);
 
@@ -173,7 +180,7 @@ int cpu_up(unsigned int cpu)
     return 0;
 
  fail:
-    cpu_notifier_call_chain(cpu, CPU_UP_CANCELED, &nb, true);
+    cpu_notifier_call_chain_nofail(cpu, CPU_UP_CANCELED, &nb);
  out:
     cpu_hotplug_done();
     return err;
@@ -181,7 +188,7 @@ int cpu_up(unsigned int cpu)
 
 void notify_cpu_starting(unsigned int cpu)
 {
-    cpu_notifier_call_chain(cpu, CPU_STARTING, NULL, true);
+    cpu_notifier_call_chain_nofail(cpu, CPU_STARTING, NULL);
 }
 
 static cpumask_t frozen_cpus;
@@ -237,7 +244,7 @@ void enable_nonboot_cpus(void)
     }
 
     for_each_cpu ( cpu, &frozen_cpus )
-        cpu_notifier_call_chain(cpu, CPU_RESUME_FAILED, NULL, true);
+        cpu_notifier_call_chain_nofail(cpu, CPU_RESUME_FAILED, NULL);
 
     cpumask_clear(&frozen_cpus);
 }
-- 
2.34.1