[ovs-dev] [PATCH v5 3/4] netlink: support for asynchronous NL transactions

[Sorin Vinturis]

Modified 'nl_sock_transact_multiple__' function to send asynchronous
I/O requests to the kernel driver.

Signed-off-by: Sorin Vinturis <svinturis at cloudbasesolutions.com>
Reported-by: Alin Gabriel Serdean <aserdean at cloudbasesolutions.com>
Reported-at: https://github.com/openvswitch/ovs-issues/issues/64
---
v5: No changes compared to previous version.
---
 lib/netlink-socket.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/lib/netlink-socket.c b/lib/netlink-socket.c
index 42eb232..63b78d9 100644
--- a/lib/netlink-socket.c
+++ b/lib/netlink-socket.c
@@ -802,7 +802,7 @@ nl_sock_transact_multiple__(struct nl_sock *sock,
                               txn->request->data,
                               txn->request->size,
                               reply_buf, sizeof reply_buf,
-                              &reply_len, NULL);
+                              &reply_len, &sock->overlapped);
 
         if (ret && reply_len == 0) {
             /*
@@ -815,11 +815,28 @@ nl_sock_transact_multiple__(struct nl_sock *sock,
                 ofpbuf_clear(txn->reply);
             }
         } else if (!ret) {
-            /* XXX: Map to a more appropriate error. */
-            error = EINVAL;
-            VLOG_DBG_RL(&rl, "fatal driver failure: %s",
-                ovs_lasterror_to_string());
-            break;
+            if (GetLastError() != ERROR_IO_PENDING) {
+                /* XXX: Map to a more appropriate error. */
+                error = EINVAL;
+                VLOG_DBG_RL(&rl, "fatal driver failure: %s",
+                            ovs_lasterror_to_string());
+                break;
+            } else {
+                /* Operation is pending and will complete in the future.
+                 * Wait for the operation to complete before continuing. */
+                if (!GetOverlappedResult(sock->handle,
+                                         &sock->overlapped,
+                                         &reply_len,
+                                         TRUE)) {
+                    /* Operation has completed, but it failed. */
+                    /* XXX: Map to a more appropriate error. */
+                    error = EINVAL;
+                    VLOG_DBG_RL(
+                        &rl, "fatal driver asynchronous operation failure: %s",
+                        ovs_lasterror_to_string());
+                    break;
+                }
+            }
         }
 
         if (reply_len != 0) {
-- 
1.9.0.msysgit.0