Re: [Qemu-devel] [Qemu-block] [PATCH 3/6] curl: Pass CURLSocket to curl_multi_{do, read}()

[John Snow <jsnow@redhat.com>]

On 8/27/19 12:34 PM, Max Reitz wrote:
> curl_multi_do_locked() currently marks all sockets as ready.  That is
> not only inefficient, but in fact unsafe (the loop is).  A follow-up
> patch will change that, but to do so, curl_multi_do_locked() needs to
> know exactly which socket is ready; and that is accomplished by this
> patch here.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/curl.c | 29 ++++++++++++++++-------------
>  1 file changed, 16 insertions(+), 13 deletions(-)
> 
> diff --git a/block/curl.c b/block/curl.c
> index 8a45b371cc..05f77a38c2 100644
> --- a/block/curl.c
> +++ b/block/curl.c
> @@ -189,15 +189,15 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
>      switch (action) {
>          case CURL_POLL_IN:
>              aio_set_fd_handler(s->aio_context, fd, false,
> -                               curl_multi_read, NULL, NULL, state);
> +                               curl_multi_read, NULL, NULL, socket);
>              break;
>          case CURL_POLL_OUT:
>              aio_set_fd_handler(s->aio_context, fd, false,
> -                               NULL, curl_multi_do, NULL, state);
> +                               NULL, curl_multi_do, NULL, socket);
>              break;
>          case CURL_POLL_INOUT:
>              aio_set_fd_handler(s->aio_context, fd, false,
> -                               curl_multi_read, curl_multi_do, NULL, state);
> +                               curl_multi_read, curl_multi_do, NULL, socket);
>              break;
>          case CURL_POLL_REMOVE:
>              aio_set_fd_handler(s->aio_context, fd, false,
> @@ -394,9 +394,10 @@ static void curl_multi_check_completion(BDRVCURLState *s)
>  }
>  
>  /* Called with s->mutex held.  */
> -static void curl_multi_do_locked(CURLState *s)
> +static void curl_multi_do_locked(CURLSocket *ready_socket)
>  {
>      CURLSocket *socket, *next_socket;
> +    CURLState *s = socket->state;

Did you mean to use ready_socket here instead?

>      int running;
>      int r;
>  
> @@ -415,21 +416,23 @@ static void curl_multi_do_locked(CURLState *s)
>  
>  static void curl_multi_do(void *arg)
>  {
> -    CURLState *s = (CURLState *)arg;
> +    CURLSocket *socket = arg;
> +    BDRVCURLState *s = socket->state->s;
>  
> -    qemu_mutex_lock(&s->s->mutex);
> -    curl_multi_do_locked(s);
> -    qemu_mutex_unlock(&s->s->mutex);
> +    qemu_mutex_lock(&s->mutex);
> +    curl_multi_do_locked(socket);
> +    qemu_mutex_unlock(&s->mutex);
>  }
>  
>  static void curl_multi_read(void *arg)
>  {
> -    CURLState *s = (CURLState *)arg;
> +    CURLSocket *socket = arg;
> +    BDRVCURLState *s = socket->state->s;
>  
> -    qemu_mutex_lock(&s->s->mutex);
> -    curl_multi_do_locked(s);
> -    curl_multi_check_completion(s->s);
> -    qemu_mutex_unlock(&s->s->mutex);

bye bye &s->s->mutex ! you're very nasty !!

> +    qemu_mutex_lock(&s->mutex);
> +    curl_multi_do_locked(socket);
> +    curl_multi_check_completion(s);
> +    qemu_mutex_unlock(&s->mutex);
>  }
>  
>  static void curl_multi_timeout_do(void *arg)
>