From 1666ea1986c2fdce3bc27aa96ae6bf3a632dbc99 Mon Sep 17 00:00:00 2001

From: Nigel Croxon <ncroxon@redhat.com>

Date: Wed, 31 Jul 2013 15:12:17 +0200

Subject: Introduce async_run_on_cpu

RH-Author: Nigel Croxon <ncroxon@redhat.com>

Message-id: <1375283539-18714-2-git-send-email-ncroxon@redhat.com>

Patchwork-id: 52874

O-Subject: [RHEL7 PATCH 1/3] Introduce async_run_on_cpu

Bugzilla: 985958

RH-Acked-by: Orit Wasserman <owasserm@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

Bugzilla: 985958 - Throttle-down guest to help with live migration convergence (backport to RHEL7.0)

https://bugzilla.redhat.com/show_bug.cgi?id=985958

Backported from the following upstream commit:

commit 3c02270db980007424d797506301826310ce2db4

Author: Chegu Vinod <chegu_vinod@hp.com>

Date:   Mon Jun 24 03:49:41 2013 -0600

    Introduce async_run_on_cpu()

    Introduce an asynchronous version of run_on_cpu() i.e. the caller

    doesn't have to block till the call back routine finishes execution

    on the target vcpu.

    Signed-off-by: Chegu Vinod <chegu_vinod@hp.com>

    Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

    Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/cpus.c b/cpus.c

index c232265..8cd4eab 100644

--- a/cpus.c

+++ b/cpus.c

@@ -653,6 +653,7 @@ void run_on_cpu(CPUState *cpu, void (*func)(void *data), void *data)

     wi.func = func;

     wi.data = data;

+    wi.free = false;

     if (cpu->queued_work_first == NULL) {

         cpu->queued_work_first = &wi;

     } else {

@@ -671,6 +672,31 @@ void run_on_cpu(CPUState *cpu, void (*func)(void *data), void *data)

     }

 }

+void async_run_on_cpu(CPUState *cpu, void (*func)(void *data), void *data)

+{

+    struct qemu_work_item *wi;

+

+    if (qemu_cpu_is_self(cpu)) {

+        func(data);

+        return;

+    }

+

+    wi = g_malloc0(sizeof(struct qemu_work_item));

+    wi->func = func;

+    wi->data = data;

+    wi->free = true;

+    if (cpu->queued_work_first == NULL) {

+        cpu->queued_work_first = wi;

+    } else {

+        cpu->queued_work_last->next = wi;

+    }

+    cpu->queued_work_last = wi;

+    wi->next = NULL;

+    wi->done = false;

+

+    qemu_cpu_kick(cpu);

+}

+

 static void flush_queued_work(CPUState *cpu)

 {

     struct qemu_work_item *wi;

@@ -683,6 +709,9 @@ static void flush_queued_work(CPUState *cpu)

         cpu->queued_work_first = wi->next;

         wi->func(wi->data);

         wi->done = true;

+        if (wi->free) {

+            g_free(wi);

+        }

     }

     cpu->queued_work_last = NULL;

     qemu_cond_broadcast(&qemu_work_cond);

diff --git a/include/qemu-common.h b/include/qemu-common.h

index 3b1ca8e..73c6419 100644

--- a/include/qemu-common.h

+++ b/include/qemu-common.h

@@ -288,6 +288,7 @@ struct qemu_work_item {

     void (*func)(void *data);

     void *data;

     int done;

+    bool free;

 };

 #ifdef CONFIG_USER_ONLY

diff --git a/include/qom/cpu.h b/include/qom/cpu.h

index 7cd9442..46465e9 100644

--- a/include/qom/cpu.h

+++ b/include/qom/cpu.h

@@ -265,6 +265,16 @@ bool cpu_is_stopped(CPUState *cpu);

 void run_on_cpu(CPUState *cpu, void (*func)(void *data), void *data);

 /**

+ * async_run_on_cpu:

+ * @cpu: The vCPU to run on.

+ * @func: The function to be executed.

+ * @data: Data to pass to the function.

+ *

+ * Schedules the function @func for execution on the vCPU @cpu asynchronously.

+ */

+void async_run_on_cpu(CPUState *cpu, void (*func)(void *data), void *data);

+

+/**

  * qemu_for_each_cpu:

  * @func: The function to be executed.

  * @data: Data to pass to the function.