hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg()

Most of the retries can be done within a millisecond successfully, so we
sleep 1ms before the first retry, then gradually increase the retry
interval to 2^n with max value of 2048ms. Doing so, we will have shorter
overall delay time, because most of the cases succeed within 1-2 attempts.

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

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 583d7d42b46d..b27220a425f4 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -422,6 +422,7 @@ int vmbus_post_msg(void *buffer, size_t buflen)
         union hv_connection_id conn_id;
         int ret = 0;
         int retries = 0;
+        u32 msec = 1;
 
         conn_id.asu32 = 0;
         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
@@ -431,7 +432,7 @@ int vmbus_post_msg(void *buffer, size_t buflen)
          * insufficient resources. Retry the operation a couple of
          * times before giving up.
          */
-        while (retries < 10) {
+        while (retries < 20) {
                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 
                 switch (ret) {
@@ -454,7 +455,9 @@ int vmbus_post_msg(void *buffer, size_t buflen)
                 }
 
                 retries++;
-                msleep(1000);
+                msleep(msec);
+                if (msec < 2048)
+                        msec *= 2;
         }
         return ret;
 }