Return the correct status when a partially completed request is cancelled.

After the previous changes to fix requests on blocking sockets to complete
across multiple operations, an edge case exists where a request can be
cancelled after it has partially completed.  POSIX doesn't appear to
dictate exactly how to handle this case, but in general I feel that
aio_cancel() should arrange to cancel any request it can, but that any
partially completed requests should return a partial completion rather
than ECANCELED.  To that end, fix the socket AIO cancellation routine to
return a short read/write if a partially completed request is cancelled
rather than ECANCELED.

Sponsored by:	Chelsio Communications

1 files changed, 6 insertions, 1 deletions

diff --git a/sys/kern/sys_socket.c b/sys/kern/sys_socket.c
index ffd59df76774..fb7eb96b5674 100644
--- a/sys/kern/sys_socket.c
+++ b/sys/kern/sys_socket.c
@@ -721,6 +721,7 @@ soo_aio_cancel(struct kaiocb *job)
 {
 	struct socket *so;
 	struct sockbuf *sb;
+	long done;
 	int opcode;
 
 	so = job->fd_file->f_data;
@@ -739,7 +740,11 @@ soo_aio_cancel(struct kaiocb *job)
 		sb->sb_flags &= ~SB_AIO;
 	SOCKBUF_UNLOCK(sb);
 
-	aio_cancel(job);
+	done = job->uaiocb._aiocb_private.status;
+	if (done != 0)
+		aio_complete(job, done, 0);
+	else
+		aio_cancel(job);
 }
 
 static int