qemu-char: check errno together with ret < 0

In the tcp_chr_write function, we checked errno,
but errno was not reset before a read or write operation.
Therefore, this check of errno's actions is often
incorrect after EAGAIN has occurred.
we need check errno together with ret < 0.

Signed-off-by: xinhua.Cao <caoxinhua@huawei.com>
Message-Id: <20180704033642.15996-1-caoxinhua@huawei.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Fixes: 9fc53a10f81d3a9027b23fa810147d21be29e614
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 17519ec58991ba24cb44bccf58e8f52e584ccdce..efbad6ee7cd27b664d31ded6dca2087becb94da1 100644 (file)
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -134,8 +134,11 @@ static int tcp_chr_write(Chardev *chr, const uint8_t *buf, int len)
                                         s->write_msgfds,
                                         s->write_msgfds_num);
 
-        /* free the written msgfds in any cases other than errno==EAGAIN */
-        if (EAGAIN != errno && s->write_msgfds_num) {
+        /* free the written msgfds in any cases
+         * other than ret < 0 && errno == EAGAIN
+         */
+        if (!(ret < 0 && EAGAIN == errno)
+            && s->write_msgfds_num) {
             g_free(s->write_msgfds);
             s->write_msgfds = 0;
             s->write_msgfds_num = 0;