Re: [Qemu-devel] [PATCH for-4.0 v9 12/16] qemu_thread: supplement error handling for iothread_complete/qemu_signalfd_compat

[Markus Armbruster]

Fei Li <address@hidden> writes:

> For iothread_complete: utilize the existed errp to propagate the
> error and do the corresponding cleanup to replace the temporary
> &error_abort.
>
> For qemu_signalfd_compat: add a local_err to hold the error, and
> return the corresponding error code to replace the temporary
> &error_abort.

I'd split the patch.

>
> Cc: Markus Armbruster <address@hidden>
> Cc: Eric Blake <address@hidden>
> Signed-off-by: Fei Li <address@hidden>
> ---
>  iothread.c      | 17 +++++++++++------
>  util/compatfd.c | 11 ++++++++---
>  2 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/iothread.c b/iothread.c
> index 8e8aa01999..7335dacf0b 100644
> --- a/iothread.c
> +++ b/iothread.c
> @@ -164,9 +164,7 @@ static void iothread_complete(UserCreatable *obj, Error 
> **errp)
>                                  &local_error);
>      if (local_error) {
>          error_propagate(errp, local_error);
> -        aio_context_unref(iothread->ctx);
> -        iothread->ctx = NULL;
> -        return;
> +        goto fail;
>      }
>  
>      qemu_mutex_init(&iothread->init_done_lock);
> @@ -178,9 +176,12 @@ static void iothread_complete(UserCreatable *obj, Error 
> **errp)
>       */
>      name = object_get_canonical_path_component(OBJECT(obj));
>      thread_name = g_strdup_printf("IO %s", name);
> -    /* TODO: let the further caller handle the error instead of abort() here 
> */
> -    qemu_thread_create(&iothread->thread, thread_name, iothread_run,
> -                       iothread, QEMU_THREAD_JOINABLE, &error_abort);
> +    if (!qemu_thread_create(&iothread->thread, thread_name, iothread_run,
> +                            iothread, QEMU_THREAD_JOINABLE, errp)) {
> +        g_free(thread_name);
> +        g_free(name);

I suspect you're missing cleanup here:

           qemu_cond_destroy(&iothread->init_done_cond);
           qemu_mutex_destroy(&iothread->init_done_lock);

But I'm not 100% sure, to be honest.  Stefan, can you help?


> +        goto fail;
> +    }
>      g_free(thread_name);
>      g_free(name);
>  

I'd avoid the code duplication like this:

       thread_ok = qemu_thread_create(&iothread->thread, thread_name,
                                      iothread_run, iothread,
                                      QEMU_THREAD_JOINABLE, errp);
       g_free(thread_name);
       g_free(name);
       if (!thread_ok) {
           qemu_cond_destroy(&iothread->init_done_cond);
           qemu_mutex_destroy(&iothread->init_done_lock);
           goto fail;
       }

Matter of taste.

Hmm, iothread.c has no maintainer.  Stefan, you created it, would you be
willing to serve as maintainer?

> @@ -191,6 +192,10 @@ static void iothread_complete(UserCreatable *obj, Error 
> **errp)
>                         &iothread->init_done_lock);
>      }
>      qemu_mutex_unlock(&iothread->init_done_lock);
> +    return;
> +fail:
> +    aio_context_unref(iothread->ctx);
> +    iothread->ctx = NULL;
>  }
>  
>  typedef struct {
> diff --git a/util/compatfd.c b/util/compatfd.c
> index c3d8448264..9cb13381e4 100644
> --- a/util/compatfd.c
> +++ b/util/compatfd.c
> @@ -71,6 +71,7 @@ static int qemu_signalfd_compat(const sigset_t *mask)
>      struct sigfd_compat_info *info;
>      QemuThread thread;
>      int fds[2];
> +    Error *local_err = NULL;
>  
>      info = malloc(sizeof(*info));
>      if (info == NULL) {
> @@ -89,9 +90,13 @@ static int qemu_signalfd_compat(const sigset_t *mask)
>      memcpy(&info->mask, mask, sizeof(*mask));
>      info->fd = fds[1];
>  
> -    /* TODO: let the further caller handle the error instead of abort() here 
> */
> -    qemu_thread_create(&thread, "signalfd_compat", sigwait_compat,
> -                       info, QEMU_THREAD_DETACHED, &error_abort);
> +    if (!qemu_thread_create(&thread, "signalfd_compat", sigwait_compat,
> +                            info, QEMU_THREAD_DETACHED, &local_err)) {
> +        close(fds[0]);
> +        close(fds[1]);
> +        free(info);
> +        return -1;

Leaks @local_err.  Pass NULL instead.

> +    }
>  
>      return fds[0];
>  }