[PATCH RFC 2/5] cpus-common: Add run_on_cpu2()

[Peter Xu <peterx@redhat.com>]

This version of run_on_cpu() allows to take an Error** to detect errors.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 cpus-common.c         | 27 +++++++++++++++++++++++++++
 include/hw/core/cpu.h | 26 ++++++++++++++++++++++++++
 softmmu/cpus.c        |  6 ++++++
 3 files changed, 59 insertions(+)

diff --git a/cpus-common.c b/cpus-common.c
index 1db7bbbb88..1d67c0c655 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -167,6 +167,33 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data,
     }
 }
 
+void do_run_on_cpu2(CPUState *cpu, run_on_cpu_func2 func2, run_on_cpu_data data,
+                    QemuMutex *mutex, Error **errp)
+{
+    struct qemu_work_item wi;
+
+    if (qemu_cpu_is_self(cpu)) {
+        func2(cpu, data, errp);
+        return;
+    }
+
+    wi.func2 = func2;
+    wi.data = data;
+    wi.done = false;
+    wi.free = false;
+    wi.exclusive = false;
+    wi.has_errp = true;
+    wi.errp = errp;
+
+    queue_work_on_cpu(cpu, &wi);
+    while (!qatomic_mb_read(&wi.done)) {
+        CPUState *self_cpu = current_cpu;
+
+        qemu_cond_wait(&qemu_work_cond, mutex);
+        current_cpu = self_cpu;
+    }
+}
+
 void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
 {
     struct qemu_work_item *wi;
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 7a303576d0..4bb40a03cf 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -709,6 +709,19 @@ bool cpu_is_stopped(CPUState *cpu);
 void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data,
                    QemuMutex *mutex);
 
+/**
+ * do_run_on_cpu2:
+ * @cpu: The vCPU to run on.
+ * @func2: The function to be executed.
+ * @data: Data to pass to the function.
+ * @mutex: Mutex to release while waiting for @func2 to run.
+ * @errp: The Error** pointer to be passed into @func2.
+ *
+ * Used internally in the implementation of run_on_cpu2.
+ */
+void do_run_on_cpu2(CPUState *cpu, run_on_cpu_func2 func2, run_on_cpu_data data,
+                    QemuMutex *mutex, Error **errp);
+
 /**
  * run_on_cpu:
  * @cpu: The vCPU to run on.
@@ -719,6 +732,19 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data,
  */
 void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data);
 
+/**
+ * run_on_cpu2:
+ * @cpu: The vCPU to run on.
+ * @func: The function to be executed.
+ * @data: Data to pass to the function.
+ * @errp: The Error** pointer to be passed into @func2.
+ *
+ * Schedules the function @func2 for execution on the vCPU @cpu, capture
+ * any error and put it into *@errp when provided.
+ */
+void run_on_cpu2(CPUState *cpu, run_on_cpu_func2 func2, run_on_cpu_data data,
+                 Error **errp);
+
 /**
  * async_run_on_cpu:
  * @cpu: The vCPU to run on.
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 23b30484b2..898363a1d0 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -391,6 +391,12 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
     do_run_on_cpu(cpu, func, data, &qemu_global_mutex);
 }
 
+void run_on_cpu2(CPUState *cpu, run_on_cpu_func2 func2, run_on_cpu_data data,
+                 Error **errp)
+{
+    do_run_on_cpu2(cpu, func2, data, &qemu_global_mutex, errp);
+}
+
 static void qemu_cpu_stop(CPUState *cpu, bool exit)
 {
     g_assert(qemu_cpu_is_self(cpu));
-- 
2.32.0