On 29/04/2015 12:37, Fam Zheng wrote:
> Achieved by:
>
> - Remembering the server fd with a global variable, in order to access
> it from nbd_client_closed.
>
> - Checking nbd_can_accept() and updating server_fd handler whenever
> client connects or disconnects.
>
> Signed-off-by: Fam Zheng <f...@redhat.com>
> ---
> qemu-nbd.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index 7e690ff..5af6d11 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
> @@ -53,6 +53,7 @@ static int persistent = 0;
> static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;
> static int shared = 1;
> static int nb_fds;
> +static int server_fd;
>
> static void usage(const char *name)
> {
> @@ -340,7 +341,7 @@ out:
> return (void *) EXIT_FAILURE;
> }
>
> -static int nbd_can_accept(void *opaque)
> +static int nbd_can_accept(void)
> {
> return nb_fds < shared;
> }
> @@ -351,19 +352,21 @@ static void nbd_export_closed(NBDExport *exp)
> state = TERMINATED;
> }
>
> +static void nbd_update_server_fd_handler(int fd);
> +
> static void nbd_client_closed(NBDClient *client)
> {
> nb_fds--;
> if (nb_fds == 0 && !persistent && state == RUNNING) {
> state = TERMINATE;
> }
> + nbd_update_server_fd_handler(server_fd);
> qemu_notify_event();
> nbd_client_put(client);
> }
>
> static void nbd_accept(void *opaque)
> {
> - int server_fd = (uintptr_t) opaque;
> struct sockaddr_in addr;
> socklen_t addr_len = sizeof(addr);
>
> @@ -380,12 +383,22 @@ static void nbd_accept(void *opaque)
>
> if (nbd_client_new(exp, fd, nbd_client_closed)) {
> nb_fds++;
> + nbd_update_server_fd_handler(server_fd);
> } else {
> shutdown(fd, 2);
> close(fd);
> }
> }
>
> +static void nbd_update_server_fd_handler(int fd)
> +{
> + if (nbd_can_accept()) {
> + qemu_set_fd_handler(fd, nbd_accept, NULL, (void *)(uintptr_t)fd);
> + } else {
> + qemu_set_fd_handler(fd, NULL, NULL, NULL);
> + }
> +}
> +
> int main(int argc, char **argv)
> {
> BlockBackend *blk;
> @@ -761,8 +774,8 @@ int main(int argc, char **argv)
> memset(&client_thread, 0, sizeof(client_thread));
> }
>
> - qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL,
> - (void *)(uintptr_t)fd);
> + server_fd = fd;
> + nbd_update_server_fd_handler(fd);
>
> /* now when the initialization is (almost) complete, chdir("/")
> * to free any busy filesystems */
>
Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>
