[PULL,03/25] QIOChannelSocket: Fix zero-copy send so socket flush works

Commit Message

Dr. David Alan Gilbert June 23, 2022, 4:53 p.m. UTC

From: Leonardo Bras <[e-mail]>

Somewhere between v6 and v7 the of the zero-copy-send patchset a crucial
part of the flushing mechanism got missing: incrementing zero_copy_queued.

Without that, the flushing interface becomes a no-op, and there is no
guarantee the buffer is really sent.

This can go as bad as causing a corruption in RAM during migration.

Fixes: 2bc58ffc2926 ("QIOChannelSocket: Implement io_writev zero copy flag & io_flush for CONFIG_LINUX")
Reported-by: 徐闯 <[e-mail]>
Signed-off-by: Leonardo Bras <[e-mail]>
Reviewed-by: Daniel P. Berrangé <[e-mail]>
Reviewed-by: Peter Xu <[e-mail]>
Reviewed-by: Juan Quintela <[e-mail]>
Signed-off-by: Juan Quintela <[e-mail]>
Signed-off-by: Dr. David Alan Gilbert <[e-mail]>
---
 io/channel-socket.c | 5 +++++
 1 file changed, 5 insertions(+)

Patch

diff --git a/io/channel-socket.c b/io/channel-socket.c
index b8c13dba7c..4466bb1cd4 100644
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -611,6 +611,11 @@  static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
                          "Unable to write to socket");
         return -1;
     }
+
+    if (flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) {
+        sioc->zero_copy_queued++;
+    }
+
     return ret;
 }
 #else /* WIN32 */