From: Daniel P. Berrangé <berra...@redhat.com> This commit results in unexpected termination of the TLS connection. When 'fd_can_read' returns 0, the code goes on to pass a zero length buffer to qio_channel_read. The TLS impl calls into gnutls_recv() with this zero length buffer, at which point GNUTLS returns an error GNUTLS_E_INVALID_REQUEST. This is treated as fatal by QEMU's TLS code resulting in the connection being torn down by the chardev.
Simply skipping the qio_channel_read when the buffer length is zero is also not satisfactory, as it results in a high CPU burn busy loop massively slowing QEMU's functionality. The proper solution is to avoid tcp_chr_read being called at all unless the frontend is able to accept more data. This will be done in a followup commit. This reverts commit 462945cd22d2bcd233401ed3aa167d83a8e35b05 Reviewed-by: Thomas Huth <th...@redhat.com> Signed-off-by: Daniel P. Berrangé <berra...@redhat.com> (cherry picked from commit e8ee827ffdb86ebbd5f5213a1f78123c25a90864) Signed-off-by: Michael Tokarev <m...@tls.msk.ru> diff --git a/chardev/char-socket.c b/chardev/char-socket.c index 034840593d..73947da188 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -492,9 +492,9 @@ static gboolean tcp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque) s->max_size <= 0) { return TRUE; } - len = tcp_chr_read_poll(opaque); - if (len > sizeof(buf)) { - len = sizeof(buf); + len = sizeof(buf); + if (len > s->max_size) { + len = s->max_size; } size = tcp_chr_recv(chr, (void *)buf, len); if (size == 0 || (size == -1 && errno != EAGAIN)) { -- 2.39.2