Re: [PATCH] vhost-user-test: no set non-blocking for cal fd less than 0.

[Michael S. Tsirkin]

On Thu, Apr 11, 2024 at 03:35:55PM +0800, Yuxue Liu yuxue.liu@jaguarmicro.com 
wrote:
> From: Yuxue Liu <yuxue.liu@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.liu@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