Re: [Qemu-devel] [PATCH] eventfd: making it rhread safe

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jul 02, 2012 at 05:48:16AM +1000, Alexey Kardashevskiy wrote:
>Subject: Re: [PATCH] eventfd: making it rhread safe

typo in the subject

> QEMU uses IO handlers to run select() in the main loop. The handlers list is managed by qemu_set_fd_handler() helper which works fine when called from the main thread as it is called not when select() is waiting.

git commit logs should break lines at 70-80 chars.
Sometimes people go beyond that a bit. But 214 chars is not reasonable.

> However sometime we need to update the handlers list from another thread.

Want to be more specific?

> For that the main loop's select() needs to be restarted with the updated list.
> 
> The patch adds the qemu_notify_event() call to interrupt select() and make wrapping code to restart select() with the updated IO handlers list.

What does 'and make wrapping code' mean?

> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Does this fix any bugs? If yes commit log should mention this.

> ---
>  iohandler.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/iohandler.c b/iohandler.c
> index 3c74de6..dea4355 100644
> --- a/iohandler.c
> +++ b/iohandler.c
> @@ -77,6 +77,7 @@ int qemu_set_fd_handler2(int fd,
>          ioh->fd_write = fd_write;
>          ioh->opaque = opaque;
>          ioh->deleted = 0;
> +        qemu_notify_event();
>      }
>      return 0;
>  }
> -- 
> 1.7.10