Re: [PATCH v2 04/10] ftrace: Store direct called addresses in their ops

[Steven Rostedt]

On Tue,  7 Feb 2023 19:21:29 +0100
Florent Revest <revest@xxxxxxxxxxxx> wrote:

> @@ -5445,6 +5445,7 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
>  	/* Enable the tmp_ops to have the same functions as the direct ops */
>  	ftrace_ops_init(&tmp_ops);
>  	tmp_ops.func_hash = ops->func_hash;
> +	tmp_ops.direct_call = addr;
>  
>  	err = register_ftrace_function_nolock(&tmp_ops);
>  	if (err)
> @@ -5466,6 +5467,7 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
>  			entry->direct = addr;
>  		}
>  	}
> +	WRITE_ONCE(ops->direct_call, addr);

I'm curious about the use of WRITE_ONCE(). It should not go outside the
mutex barrier.

-- Steve

>  
>  	mutex_unlock(&ftrace_lock);
>