patch-0002-xen-add-helper-for-calling-notifier_call_chain-to-co.patch

From 3816d82fba6c67b599c970dfe7bc8e024b7e2042 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Tue, 2 Apr 2019 07:34:53 +0200
Subject: [PATCH 2/9] xen: add helper for calling notifier_call_chain() to
 common/cpu.c

Add a helper cpu_notifier_call_chain() to call notifier_call_chain()
for a cpu with a specified action, returning an errno value.

This avoids coding the same pattern multiple times.

While at it avoid side effects from using BUG_ON() by not using
cpu_online(cpu) as a parameter.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Dario Faggioli <dfaggioli@suse.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 8d88eacb3b390984e2c483d75d8f40b3ec4be67c)
---
 xen/common/cpu.c | 56 ++++++++++++++++++++++--------------------------
 1 file changed, 26 insertions(+), 30 deletions(-)

diff --git a/xen/common/cpu.c b/xen/common/cpu.c
index ca415babf8d2..ccf62b5e013e 100644
--- a/xen/common/cpu.c
+++ b/xen/common/cpu.c
@@ -68,11 +68,21 @@ void __init register_cpu_notifier(struct notifier_block *nb)
     spin_unlock(&cpu_add_remove_lock);
 }
 
+static int cpu_notifier_call_chain(unsigned int cpu, unsigned long action,
+                                   struct notifier_block **nb, bool nofail)
+{
+    void *hcpu = (void *)(long)cpu;
+    int notifier_rc = notifier_call_chain(&cpu_chain, action, hcpu, nb);
+    int ret = (notifier_rc == NOTIFY_DONE) ? 0 : notifier_to_errno(notifier_rc);
+
+    BUG_ON(ret && nofail);
+
+    return ret;
+}
+
 static void _take_cpu_down(void *unused)
 {
-    void *hcpu = (void *)(long)smp_processor_id();
-    int notifier_rc = notifier_call_chain(&cpu_chain, CPU_DYING, hcpu, NULL);
-    BUG_ON(notifier_rc != NOTIFY_DONE);
+    cpu_notifier_call_chain(smp_processor_id(), CPU_DYING, NULL, true);
     __cpu_disable();
 }
 
@@ -84,8 +94,7 @@ static int take_cpu_down(void *arg)
 
 int cpu_down(unsigned int cpu)
 {
-    int err, notifier_rc;
-    void *hcpu = (void *)(long)cpu;
+    int err;
     struct notifier_block *nb = NULL;
 
     if ( !cpu_hotplug_begin() )
@@ -97,12 +106,9 @@ int cpu_down(unsigned int cpu)
         return -EINVAL;
     }
 
-    notifier_rc = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE, hcpu, &nb);
-    if ( notifier_rc != NOTIFY_DONE )
-    {
-        err = notifier_to_errno(notifier_rc);
+    err = cpu_notifier_call_chain(cpu, CPU_DOWN_PREPARE, &nb, false);
+    if ( err )
         goto fail;
-    }
 
     if ( unlikely(system_state < SYS_STATE_active) )
         on_selected_cpus(cpumask_of(cpu), _take_cpu_down, NULL, true);
@@ -110,26 +116,24 @@ int cpu_down(unsigned int cpu)
         goto fail;
 
     __cpu_die(cpu);
-    BUG_ON(cpu_online(cpu));
+    err = cpu_online(cpu);
+    BUG_ON(err);
 
-    notifier_rc = notifier_call_chain(&cpu_chain, CPU_DEAD, hcpu, NULL);
-    BUG_ON(notifier_rc != NOTIFY_DONE);
+    cpu_notifier_call_chain(cpu, CPU_DEAD, NULL, true);
 
     send_global_virq(VIRQ_PCPU_STATE);
     cpu_hotplug_done();
     return 0;
 
  fail:
-    notifier_rc = notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, hcpu, &nb);
-    BUG_ON(notifier_rc != NOTIFY_DONE);
+    cpu_notifier_call_chain(cpu, CPU_DOWN_FAILED, &nb, true);
     cpu_hotplug_done();
     return err;
 }
 
 int cpu_up(unsigned int cpu)
 {
-    int notifier_rc, err = 0;
-    void *hcpu = (void *)(long)cpu;
+    int err;
     struct notifier_block *nb = NULL;
 
     if ( !cpu_hotplug_begin() )
@@ -141,19 +145,15 @@ int cpu_up(unsigned int cpu)
         return -EINVAL;
     }
 
-    notifier_rc = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu, &nb);
-    if ( notifier_rc != NOTIFY_DONE )
-    {
-        err = notifier_to_errno(notifier_rc);
+    err = cpu_notifier_call_chain(cpu, CPU_UP_PREPARE, &nb, false);
+    if ( err )
         goto fail;
-    }
 
     err = __cpu_up(cpu);
     if ( err < 0 )
         goto fail;
 
-    notifier_rc = notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu, NULL);
-    BUG_ON(notifier_rc != NOTIFY_DONE);
+    cpu_notifier_call_chain(cpu, CPU_ONLINE, NULL, true);
 
     send_global_virq(VIRQ_PCPU_STATE);
 
@@ -161,18 +161,14 @@ int cpu_up(unsigned int cpu)
     return 0;
 
  fail:
-    notifier_rc = notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu, &nb);
-    BUG_ON(notifier_rc != NOTIFY_DONE);
+    cpu_notifier_call_chain(cpu, CPU_UP_CANCELED, &nb, true);
     cpu_hotplug_done();
     return err;
 }
 
 void notify_cpu_starting(unsigned int cpu)
 {
-    void *hcpu = (void *)(long)cpu;
-    int notifier_rc = notifier_call_chain(
-        &cpu_chain, CPU_STARTING, hcpu, NULL);
-    BUG_ON(notifier_rc != NOTIFY_DONE);
+    cpu_notifier_call_chain(cpu, CPU_STARTING, NULL, true);
 }
 
 static cpumask_t frozen_cpus;
-- 
2.26.2