Re: ftrace multibuffer && rcu (Was: tracing/uprobes: Supportftrace_event_file base multibuffer)

From: Oleg Nesterov
Date: Fri Jun 14 2013 - 12:23:59 EST

On 06/14, Oleg Nesterov wrote:
> So perhaps something like below (untested) makes sense? With this patch
> we can trivially convert trace_kprobe.c to use list_add/del/each_rcu.

Forgot to mention, the patch is obviously incomplete, __kprobe_trace_func()
can see the "dead" file even if its memory can't go away. But this looks

> +static inline struct event_file_link *
> +alloc_event_file_link(struct ftrace_event_file *file)
> +{
> + struct event_file_link *link = kmalloc(sizeof(*link), GFP_KERNEL);
> + if (link)
> + link->file = file;
> + return link;
> +}

And this lacks atomic_inc(file->refcnt).

In short, this is just to explain what I meant, the actual change should
probably differ.


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