linux-kernel - Re: [PATCH v8 08/12] user_events: Optimize writing events by only copying data once

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Message-ID: <20220106230545.GA2447@kbox>
Date:   Thu, 6 Jan 2022 15:05:45 -0800
From:   Beau Belgrave <beaub@...ux.microsoft.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     mhiramat@...nel.org, linux-trace-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 08/12] user_events: Optimize writing events by only
 copying data once

On Thu, Jan 06, 2022 at 05:17:45PM -0500, Steven Rostedt wrote:
> On Thu, 16 Dec 2021 09:35:07 -0800
> Beau Belgrave <beaub@...ux.microsoft.com> wrote:
> 
> > @@ -1018,16 +1081,11 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i)
> >  	if (likely(atomic_read(&tp->key.enabled) > 0)) {
> >  		struct tracepoint_func *probe_func_ptr;
> >  		user_event_func_t probe_func;
> > +		struct iov_iter copy;
> >  		void *tpdata;
> > -		void *kdata;
> > -		u32 datalen;
> > -
> > -		kdata = kmalloc(i->count, GFP_KERNEL);
> >  
> > -		if (unlikely(!kdata))
> > -			return -ENOMEM;
> > -
> > -		datalen = copy_from_iter(kdata, i->count, i);
> > +		if (unlikely(iov_iter_fault_in_readable(i, i->count)))
> 
> Can you rebase on my tree: ftrace/core ?
> 
> That's because upstream now has:
> 
> a6294593e8a12 ("iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable")
> 
> And it looks like you need to call fault_in_iov_iter_readable().
> 
> -- Steve
> 

Yep, will do.

Thanks,
-Beau