linux-kernel - Re: [RFC PATCH 27/27] epoll: take epitem list out of struct file

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Message-ID: <20201005204941.GT3421308@ZenIV.linux.org.uk>
Date:   Mon, 5 Oct 2020 21:49:41 +0100
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Qian Cai <cai@...hat.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Marc Zyngier <maz@...nel.org>
Subject: Re: [RFC PATCH 27/27] epoll: take epitem list out of struct file

On Mon, Oct 05, 2020 at 04:37:18PM -0400, Qian Cai wrote:
> On Sun, 2020-10-04 at 03:39 +0100, Al Viro wrote:
> >  /*
> >   * Must be called with "mtx" held.
> >   */
> > @@ -1367,19 +1454,21 @@ static int ep_insert(struct eventpoll *ep, const
> > struct epoll_event *event,
> >  	epi->event = *event;
> >  	epi->next = EP_UNACTIVE_PTR;
> >  
> > -	atomic_long_inc(&ep->user->epoll_watches);
> > -
> >  	if (tep)
> >  		mutex_lock(&tep->mtx);
> >  	/* Add the current item to the list of active epoll hook for this file
> > */
> > -	spin_lock(&tfile->f_lock);
> > -	hlist_add_head_rcu(&epi->fllink, &tfile->f_ep_links);
> > -	spin_unlock(&tfile->f_lock);
> > -	if (full_check && !tep) {
> > -		get_file(tfile);
> > -		list_add(&tfile->f_tfile_llink, &tfile_check_list);
> > +	if (unlikely(attach_epitem(tfile, epi) < 0)) {
> > +		kmem_cache_free(epi_cache, epi);
> > +		if (tep)
> > +			mutex_lock(&tep->mtx);
> 
> Shouldn't this be mutex_unlock() instead?

It should.  Fixed and force-pushed...

> > +		return -ENOMEM;
> >  	}
> >  
>