Re: [PATCH RFC v1 1/4] perf: Introduce extended syscall error reporting

[Peter Zijlstra <peterz@infradead.org>]

On Fri, Jul 24, 2015 at 02:45:56PM +0300, Alexander Shishkin wrote:

> @@ -3890,7 +3958,7 @@ perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
>  	ret = perf_read_hw(event, buf, count);
>  	perf_event_ctx_unlock(event, ctx);
>  
> -	return ret;
> +	return perf_error_report(&event->attr, ret);
>  }
>  
>  static unsigned int perf_poll(struct file *file, poll_table *wait)
> @@ -4103,7 +4171,7 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>  	ret = _perf_ioctl(event, cmd, arg);
>  	perf_event_ctx_unlock(event, ctx);
>  
> -	return ret;
> +	return perf_error_report(&event->attr, ret);
>  }
>  
>  #ifdef CONFIG_COMPAT

Oooh, shiny.. So not only does it work for SYSCALL time fails, it keeps
the pointer about and reports all subsequent fails in there too.