Hi Michael, Thomas
The reason is I want to merge this patch:
https://lore.kernel.org/all/seypr06mb67561abd83633689b5037395ec...@seypr06mb6756.apcprd06.prod.outlook.com/
Compilation errors occur during CI :
stderr:
**
ERROR:../tests/qtest/vhost-user-test.c:468:chr_read: assertion
failed (err == NULL): Bad file descriptor (g-unix-error-quark, 0)
**
ERROR:../tests/qtest/qos-test.c:191:subprocess_run_one_test:
child process
(/aarch64/virt/generic-pcihost/pci-bus-generic/pci-bus/virtio-net-pci/virtio-net/virtio-net-tests/vhost-user/migrate/subprocess
[22197]) failed unexpectedly (test program exited with status code -6) ――
The reason is that when the guest os uses the PMD mode, it does not enable
interrupts in the device's MSIX.
In QEMU, The function vhost_user_set_vring_call invokes vhost_set_vring_file
to send the file descriptor information, where fd=-1, thus fd_num=0.
In CI , tests/qtest/vhost-user-test
1：vhost-user-test invokes the chr_read function to handle the messages sent
by the server.
2：The chr_read function initializes the local variable fd to -1.
3：
case VHOST_USER_SET_VRING_CALL:
qemu_chr_fe_get_msgfds(chr, &fd, 1);
!!! Because s->read_msgfds_num = 0, after the function
qemu_chr_fe_get_msgfds(chr, &fd, 1) is executed, fd=-1.!!!
g_unix_set_fd_nonblocking(fd, true, &err);
!!! An exception will occur when setting nonblocking when fd < 0. !!!
g_assert_no_error(err);
Offer a modification suggestion
1：Refer to the tcp_chr_recv function:
static ssize_t
tcp_chr_recv(Chardev *chr, char *buf, size_t len)
{
SocketChardev *s =
SOCKET_CHARDEV(chr);
-----
----
for (i = 0; i <
s->read_msgfds_num; i++) {
int fd =
s->read_msgfds[i];
if (fd < 0) {
!!!!When fd < 0, the qemu_socket_set_block
function will not be called !!!!
continue;
}
/* O_NONBLOCK
is preserved across SCM_RIGHTS so reset it */
qemu_socket_set_block(fd);
2: modify chr_read function
case VHOST_USER_SET_VRING_CALL:
qemu_chr_fe_get_msgfds(chr,
&fd, 1);
if (fd <0) /* Add a condition
check. */
break;
g_unix_set_fd_nonblocking(fd,
true, &err);
g_assert_no_error(err);
Best regards,
Yuxue Liu
-----Original Message-----
From: Michael S. Tsirkin m...@redhat.com
Sent: April 18, 2024 23:41
To: Gavin Liu gavin....@jaguarmicro.com
Cc: pbonz...@redhat.com; lviv...@redhat.com; th...@redhat.com;
qemu-devel@nongnu.org
Subject: Re: [PATCH] vhost-user-test: no set non-blocking for cal fd less than
0.
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On Thu, Apr 11, 2024 at 03:35:55PM +0800, Yuxue Liu yuxue....@jaguarmicro.com
wrote:
> From: Yuxue Liu <yuxue....@jaguarmicro.com>
>
> In the scenario where vhost-user sets eventfd to -1,
> qemu_chr_fe_get_msgfds retrieves fd as -1. When vhost_user_read
> receives, it does not perform blocking operations on the descriptor
> with fd=-1, so non-blocking operations should not be performed here
> either.This is a normal use case. Calling g_unix_set_fd_nonblocking at
> this point will cause the test to interrupt.
>
> When vhost_user_write sets the call fd to -1, it sets the number of
> fds to 0, so the fds obtained by qemu_chr_fe_get_msgfds will also be
> 0.
>
> Signed-off-by: Yuxue Liu <yuxue....@jaguarmicro.com>
A bit more detail here please.
When does all this happen?
> ---
> tests/qtest/vhost-user-test.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/tests/qtest/vhost-user-test.c
> b/tests/qtest/vhost-user-test.c index d4e437265f..7c8ef6268d 100644
> --- a/tests/qtest/vhost-user-test.c
> +++ b/tests/qtest/vhost-user-test.c
> @@ -458,7 +458,10 @@ static void chr_read(void *opaque, const uint8_t *buf,
> int size)
> case VHOST_USER_SET_VRING_KICK:
> case VHOST_USER_SET_VRING_CALL:
> /* consume the fd */
> - qemu_chr_fe_get_msgfds(chr, &fd, 1);
> + if (!qemu_chr_fe_get_msgfds(chr, &fd, 1) && fd < 0) {
> + qos_printf("call fd :%d, no set non-blocking\n", fd);
> + break;
> + }
> /*
> * This is a non-blocking eventfd.
> * The receive function forces it to be blocking,
> --
> 2.43.0
