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Date:      Thu, 14 Sep 2017 13:02:18 -0700
From:      Gleb Smirnoff <glebius@FreeBSD.org>
To:        Steven Hartland <steven.hartland@multiplay.co.uk>
Cc:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   Re: svn commit: r323566 - head/sys/kern
Message-ID:  <20170914200218.GU1055@FreeBSD.org>
In-Reply-To: <4ae03e74-4fc3-d23b-4f14-3329b20b8df0@multiplay.co.uk>
References:  <201709132211.v8DMB6Pp048326@repo.freebsd.org> <4ae03e74-4fc3-d23b-4f14-3329b20b8df0@multiplay.co.uk>

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  Steven,

  I don't want to MFC that, since that will hurt performance on stable/11
due to ACCEPT_LOCK().

On Thu, Sep 14, 2017 at 08:31:57AM +0100, Steven Hartland wrote:
S> Is this something that will be MFC'ed to 11 or is this 12 / CURRENT only?
S> 
S> On 13/09/2017 23:11, Gleb Smirnoff wrote:
S> > Author: glebius
S> > Date: Wed Sep 13 22:11:05 2017
S> > New Revision: 323566
S> > URL: https://svnweb.freebsd.org/changeset/base/323566
S> >
S> > Log:
S> >    Use soref() in sendfile(2) instead fhold() to reference a socket.
S> >    
S> >    The problem is that fdrop() requires syscall context, as it may
S> >    enter sleep in some cases.  The reason to use it in the original
S> >    non-blocking sendfile implementation, was to avoid use of global
S> >    ACCEPT_LOCK() on every I/O completion. Now in head sorele() no
S> >    longer requires this lock.
S> >
S> > Modified:
S> >    head/sys/kern/kern_sendfile.c
S> >
S> > Modified: head/sys/kern/kern_sendfile.c
S> > ==============================================================================
S> > --- head/sys/kern/kern_sendfile.c	Wed Sep 13 21:56:49 2017	(r323565)
S> > +++ head/sys/kern/kern_sendfile.c	Wed Sep 13 22:11:05 2017	(r323566)
S> > @@ -80,7 +80,7 @@ struct sf_io {
S> >   	volatile u_int	nios;
S> >   	u_int		error;
S> >   	int		npages;
S> > -	struct file	*sock_fp;
S> > +	struct socket	*so;
S> >   	struct mbuf	*m;
S> >   	vm_page_t	pa[];
S> >   };
S> > @@ -255,7 +255,7 @@ static void
S> >   sendfile_iodone(void *arg, vm_page_t *pg, int count, int error)
S> >   {
S> >   	struct sf_io *sfio = arg;
S> > -	struct socket *so;
S> > +	struct socket *so = sfio->so;
S> >   
S> >   	for (int i = 0; i < count; i++)
S> >   		if (pg[i] != bogus_page)
S> > @@ -267,8 +267,6 @@ sendfile_iodone(void *arg, vm_page_t *pg, int count, i
S> >   	if (!refcount_release(&sfio->nios))
S> >   		return;
S> >   
S> > -	so = sfio->sock_fp->f_data;
S> > -
S> >   	if (sfio->error) {
S> >   		struct mbuf *m;
S> >   
S> > @@ -296,8 +294,8 @@ sendfile_iodone(void *arg, vm_page_t *pg, int count, i
S> >   		CURVNET_RESTORE();
S> >   	}
S> >   
S> > -	/* XXXGL: curthread */
S> > -	fdrop(sfio->sock_fp, curthread);
S> > +	SOCK_LOCK(so);
S> > +	sorele(so);
S> >   	free(sfio, M_TEMP);
S> >   }
S> >   
S> > @@ -724,6 +722,7 @@ retry_space:
S> >   		sfio = malloc(sizeof(struct sf_io) +
S> >   		    npages * sizeof(vm_page_t), M_TEMP, M_WAITOK);
S> >   		refcount_init(&sfio->nios, 1);
S> > +		sfio->so = so;
S> >   		sfio->error = 0;
S> >   
S> >   		nios = sendfile_swapin(obj, sfio, off, space, npages, rhpages,
S> > @@ -858,9 +857,8 @@ prepend_header:
S> >   			error = (*so->so_proto->pr_usrreqs->pru_send)
S> >   			    (so, 0, m, NULL, NULL, td);
S> >   		} else {
S> > -			sfio->sock_fp = sock_fp;
S> >   			sfio->npages = npages;
S> > -			fhold(sock_fp);
S> > +			soref(so);
S> >   			error = (*so->so_proto->pr_usrreqs->pru_send)
S> >   			    (so, PRUS_NOTREADY, m, NULL, NULL, td);
S> >   			sendfile_iodone(sfio, NULL, 0, 0);
S> >
S> 

-- 
Gleb Smirnoff



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