From 46979f6e61d0afc31be31dab797f60c4f41c3de5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Fri, 20 Jul 2018 12:18:00 +0200 Subject: [PATCH 255/268] hw/char/serial: retry write if EAGAIN MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Marc-André Lureau Message-id: <20180720121800.18952-3-marcandre.lureau@redhat.com> Patchwork-id: 81455 O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH v2 2/2] hw/char/serial: retry write if EAGAIN Bugzilla: 1592817 RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Markus Armbruster RH-Acked-by: John Snow If the chardev returns -1 with EAGAIN errno on write(), it should try to send it again (EINTR is handled by the chardev itself). This fixes commit 019288bf137183bf3407c9824655b753bfafc99f "hw/char/serial: Only retry if qemu_chr_fe_write returns 0" Tested-by: Igor Mammedov Signed-off-by: Marc-André Lureau Message-Id: <20180716110755.12499-1-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini (cherry picked from commit f3575af130c700cea060b51a89008a76dae22259) Signed-off-by: Marc-André Lureau Signed-off-by: Miroslav Rezanina --- hw/char/serial.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/hw/char/serial.c b/hw/char/serial.c index d4057bf..478f9a8 100644 --- a/hw/char/serial.c +++ b/hw/char/serial.c @@ -262,15 +262,20 @@ static void serial_xmit(SerialState *s) if (s->mcr & UART_MCR_LOOP) { /* in loopback mode, say that we just received a char */ serial_receive1(s, &s->tsr, 1); - } else if (qemu_chr_fe_write(&s->chr, &s->tsr, 1) == 0 && - s->tsr_retry < MAX_XMIT_RETRY) { - assert(s->watch_tag == 0); - s->watch_tag = - qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP, - serial_watch_cb, s); - if (s->watch_tag > 0) { - s->tsr_retry++; - return; + } else { + int rc = qemu_chr_fe_write(&s->chr, &s->tsr, 1); + + if ((rc == 0 || + (rc == -1 && errno == EAGAIN)) && + s->tsr_retry < MAX_XMIT_RETRY) { + assert(s->watch_tag == 0); + s->watch_tag = + qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP, + serial_watch_cb, s); + if (s->watch_tag > 0) { + s->tsr_retry++; + return; + } } } s->tsr_retry = 0; -- 1.8.3.1