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Re: [Qemu-devel] [PATCH] hw/char/serial: retry write if EAGAIN
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] hw/char/serial: retry write if EAGAIN |
Date: |
Mon, 16 Jul 2018 16:10:03 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 16/07/2018 13:07, Marc-André Lureau wrote:
> 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 <address@hidden>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
> 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 cd7d747c68..8bd1da2fa3 100644
> --- a/hw/char/serial.c
> +++ b/hw/char/serial.c
> @@ -261,15 +261,20 @@ 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;
>
Queued, thanks.
Paolo