Re: [Xen-devel] qemu_timer_pending/qemu_get_timer: cope with NULL timers

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2011-12-05 at 10:54 +0000, Stefano Stabellini wrote:
> qemu_timer_pending and qemu_get_timer: don't crash if the timer passed
> as an argument is NULL.

It would have been useful to mention why a NULL timer is valid here.
Apart from just being good changelog practice to explain the actual
reason for a change this would also help tell us why this issue isn't
being solved further up the stack. One the face of it this seem like
this ought to be a bug in the caller of qemu_mod_timer.

Ian.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> diff --git a/vl.c b/vl.c
> index f07a659..f3b3d02 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1201,6 +1201,10 @@ void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
>  int qemu_timer_pending(QEMUTimer *ts)
>  {
>      QEMUTimer *t;
> +
> +    if (ts == NULL)
> +        return 0;
> +
>      for(t = active_timers[ts->clock->type]; t != NULL; t = t->next) {
>          if (t == ts)
>              return 1;
> @@ -1272,6 +1276,9 @@ void qemu_get_timer(QEMUFile *f, QEMUTimer *ts)
>  {
>      uint64_t expire_time;
>  
> +    if (ts == NULL)
> +        return;
> +
>      expire_time = qemu_get_be64(f);
>      if (expire_time != -1) {
>          qemu_mod_timer(ts, expire_time);
> 
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