Drivers: hv: balloon: Execute balloon inflation in a separate context

Execute the balloon inflation operation in a separate work context.
This allows us to decouple the pressure reporting activity from the
ballooning activity. Testing has shown that this decoupling makes the
guest more reponsive.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 7fb72dd05ba21c475f5a79fb8c81f56fa77d02a8..8dc406ccf10f91d2cccd047dd4c1b20ee4ebc283 100644 (file)
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -412,6 +412,11 @@ struct dm_info_msg {
  * End protocol definitions.
  */
 
+struct balloon_state {
+       __u32 num_pages;
+       struct work_struct wrk;
+};
+
 static bool hot_add;
 static bool do_hot_add;
 /*
@@ -459,7 +464,12 @@ struct hv_dynmem_device {
        unsigned int num_pages_ballooned;
 
        /*
-        * This thread handles both balloon/hot-add
+        * State to manage the ballooning (up) operation.
+        */
+       struct balloon_state balloon_wrk;
+
+       /*
+        * This thread handles hot-add
         * requests from the host as well as notifying
         * the host with regards to memory pressure in
         * the guest.
@@ -657,9 +667,9 @@ static int  alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages,
 
 
 
-static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)
+static void balloon_up(struct work_struct *dummy)
 {
-       int num_pages = req->num_pages;
+       int num_pages = dm_device.balloon_wrk.num_pages;
        int num_ballooned = 0;
        struct dm_balloon_response *bl_resp;
        int alloc_unit;
@@ -684,14 +694,14 @@ static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)
 
 
                num_pages -= num_ballooned;
-               num_ballooned = alloc_balloon_pages(dm, num_pages,
+               num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
                                                bl_resp, alloc_unit,
                                                 &alloc_error);
 
                if ((alloc_error) || (num_ballooned == num_pages)) {
                        bl_resp->more_pages = 0;
                        done = true;
-                       dm->state = DM_INITIALIZED;
+                       dm_device.state = DM_INITIALIZED;
                }
 
                /*
@@ -719,7 +729,7 @@ static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)
                        pr_info("Balloon response failed\n");
 
                        for (i = 0; i < bl_resp->range_count; i++)
-                               free_balloon_pages(dm,
+                               free_balloon_pages(&dm_device,
                                                 &bl_resp->range_array[i]);
 
                        done = true;
@@ -775,9 +785,6 @@ static int dm_thread_func(void *dm_dev)
 
                scan_start = jiffies;
                switch (dm->state) {
-               case DM_BALLOON_UP:
-                       balloon_up(dm, (struct dm_balloon *)recv_buffer);
-                       break;
 
                case DM_HOT_ADD:
                        hot_add_req(dm, (struct dm_hot_add *)recv_buffer);
@@ -861,6 +868,7 @@ static void balloon_onchannelcallback(void *context)
        struct dm_message *dm_msg;
        struct dm_header *dm_hdr;
        struct hv_dynmem_device *dm = hv_get_drvdata(dev);
+       struct dm_balloon *bal_msg;
 
        memset(recv_buffer, 0, sizeof(recv_buffer));
        vmbus_recvpacket(dev->channel, recv_buffer,
@@ -882,8 +890,12 @@ static void balloon_onchannelcallback(void *context)
                        break;
 
                case DM_BALLOON_REQUEST:
+                       if (dm->state == DM_BALLOON_UP)
+                               pr_warn("Currently ballooning\n");
+                       bal_msg = (struct dm_balloon *)recv_buffer;
                        dm->state = DM_BALLOON_UP;
-                       complete(&dm->config_event);
+                       dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
+                       schedule_work(&dm_device.balloon_wrk.wrk);
                        break;
 
                case DM_UNBALLOON_REQUEST:
@@ -937,6 +949,7 @@ static int balloon_probe(struct hv_device *dev,
        dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
        init_completion(&dm_device.host_event);
        init_completion(&dm_device.config_event);
+       INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
 
        dm_device.thread =
                 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
@@ -1048,6 +1061,7 @@ static int balloon_remove(struct hv_device *dev)
        if (dm->num_pages_ballooned != 0)
                pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);
 
+       cancel_work_sync(&dm->balloon_wrk.wrk);
        vmbus_close(dev->channel);
        kthread_stop(dm->thread);
        kfree(send_buffer);