[Xen-changelog] [mini-os master] xenbus: notify the other end when necessary

[patchbot@xxxxxxx]

commit 22d01aab99180539b38b13ba30f0e1cd62b72147
Author:     Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Tue Oct 27 15:43:28 2015 +0000
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Mon Nov 16 11:29:23 2015 +0000

    xenbus: notify the other end when necessary
    
    The xenbus thread didn't send notification to other end when it expected
    more data or consumed responses, which led to stalling the ring from
    time to time.
    
    This is the culprit that guest was less responsive when using stubdom
    because the device model was stalled.
    
    Fix this by sending notification to the other end when it consumes a
    message. A bunch of memory barriers are also added to ensure
    correctness.
    
    Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Acked-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
---
 xenbus/xenbus.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/xenbus/xenbus.c b/xenbus/xenbus.c
index 4613ed6..0ab387a 100644
--- a/xenbus/xenbus.c
+++ b/xenbus/xenbus.c
@@ -237,6 +237,7 @@ static void xenbus_thread_func(void *ign)
                event->path = data;
                event->token = event->path + strlen(event->path) + 1;
 
+                mb();
                 xenstore_buf->rsp_cons += msg.len + sizeof(msg);
 
                 for (watch = watches; watch; watch = watch->next)
@@ -262,9 +263,13 @@ static void xenbus_thread_func(void *ign)
                     req_info[msg.req_id].reply,
                     MASK_XENSTORE_IDX(xenstore_buf->rsp_cons),
                     msg.len + sizeof(msg));
+                mb();
                 xenstore_buf->rsp_cons += msg.len + sizeof(msg);
                 wake_up(&req_info[msg.req_id].waitq);
             }
+
+            wmb();
+            notify_remote_via_evtchn(start_info.store_evtchn);
         }
     }
 }
--
generated by git-patchbot for /home/xen/git/mini-os.git#master

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