Re: [Qemu-trivial] [Qemu-devel] [PATCH 2/4] os-posix: report error message when lock file failed

[Markus Armbruster <armbru@redhat.com>]

<arei.gonglei@huawei.com> writes:

> From: Gonglei <arei.gonglei@huawei.com>
>
> It will cause that create vm failed When manager
> tool is killed forcibly (kill -9 libvirtd_pid),
> the file not was unlink, and unlock. It's better
> that report the error message for users.
>
> Signed-off-by: Huangweidong <weidong.huang@huawei.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> ---
>  os-posix.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/os-posix.c b/os-posix.c
> index 9d5ae70..89831dc 100644
> --- a/os-posix.c
> +++ b/os-posix.c
> @@ -316,6 +316,7 @@ int qemu_create_pidfile(const char *filename)
>          return -1;
>      }
>      if (lockf(fd, F_TLOCK, 0) == -1) {
> +        error_report("lock file '%s' failed: %s", filename, strerror(errno));
>          close(fd);
>          return -1;
>      }

Only called from main():

    if (pid_file && qemu_create_pidfile(pid_file) != 0) {
        os_pidfile_error();
        exit(1);
    }

I suspect the error reporting is os_pidfile_error()'s job.  And it
actually does it (POSIX version shown, W32 is simpler):

void os_pidfile_error(void)
{
    if (daemonize) {
        uint8_t status = 1;
        if (write(fds[1], &status, 1) != 1) {
            perror("daemonize. Writing to pipe\n");
        }
    } else
        fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
}

Are you sure your patch makes sense?