[Qemu-devel] Re: [PATCH] Delete IOHandlers after potentially running them

[Juan Quintela]

Stefan Hajnoczi <address@hidden> wrote:
> Since commit 4bed9837309e58d208183f81d8344996744292cf an .fd_read()
> handler that deletes its IOHandler is exposed to .fd_write() being
> called on the deleted IOHandler.
>
> This patch fixes deletion so that .fd_read() and .fd_write() are never
> called on an IOHandler that is marked for deletion.

Reviewed by: Juan Quintela <address@hidden>

But once here, what (appart from networking) reads and writes to the
same fd?  And that removes the IOHandler on read while there are write
stuff pending?

Later, Juan.

> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
>  vl.c |   15 ++++++++-------
>  1 files changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/vl.c b/vl.c
> index 7038952..6f56123 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1252,17 +1252,18 @@ void main_loop_wait(int nonblocking)
>          IOHandlerRecord *pioh;
>  
>          QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
> -            if (ioh->deleted) {
> -                QLIST_REMOVE(ioh, next);
> -                qemu_free(ioh);
> -                continue;
> -            }
> -            if (ioh->fd_read && FD_ISSET(ioh->fd, &rfds)) {
> +            if (!ioh->deleted && ioh->fd_read && FD_ISSET(ioh->fd, &rfds)) {
>                  ioh->fd_read(ioh->opaque);
>              }
> -            if (ioh->fd_write && FD_ISSET(ioh->fd, &wfds)) {
> +            if (!ioh->deleted && ioh->fd_write && FD_ISSET(ioh->fd, &wfds)) {
>                  ioh->fd_write(ioh->opaque);
>              }
> +
> +            /* Do this last in case read/write handlers marked it for 
> deletion */
> +            if (ioh->deleted) {
> +                QLIST_REMOVE(ioh, next);
> +                qemu_free(ioh);
> +            }
>          }
>      }