Re: [PATCH] FRV: Fix no-hardware-breakpoint case

[Ingo Molnar <mingo@elte.hu>]

* David Howells <dhowells@redhat.com> wrote:

> If there is no hardware breakpoint support, modify_user_hw_breakpoint() tries
> to return a NULL pointer through as an 'int' return value:
> 
> In file included from kernel/exit.c:53:
> include/linux/hw_breakpoint.h: In function 'modify_user_hw_breakpoint':
> include/linux/hw_breakpoint.h:96: warning: return makes integer from pointer without a cast
> 
> Return 0 instead.
> 
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
> 
>  include/linux/hw_breakpoint.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> 
> diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
> index 69f07a9..e268388 100644
> --- a/include/linux/hw_breakpoint.h
> +++ b/include/linux/hw_breakpoint.h
> @@ -93,7 +93,7 @@ register_user_hw_breakpoint(struct perf_event_attr *attr,
>  			    struct task_struct *tsk)	{ return NULL; }
>  static inline int
>  modify_user_hw_breakpoint(struct perf_event *bp,
> -			  struct perf_event_attr *attr)	{ return NULL; }
> +			  struct perf_event_attr *attr)	{ return 0; }

Note, this patch is wrong as it only papers over the warning without 
understanding the underlying bug: the right fix is to return an error code.

The latest perf update has the right fix - AFAICS Linus did the conflict 
resolution correctly so upstream should be fine.

	Ingo