Re: lib/53003: Problem with rust library using kqueue

[Mickael Viey <m.viey%wanadoo.fr@localhost>]

The following reply was made to PR lib/53003; it has been noted by GNATS.

From: Mickael Viey <m.viey%wanadoo.fr@localhost>
To: gnats-bugs%NetBSD.org@localhost, lib-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 netbsd-bugs%netbsd.org@localhost
Cc: 
Subject: Re: lib/53003: Problem with rust library using kqueue
Date: Sun, 11 Feb 2018 21:58:44 +0100

 > The following reply was made to PR lib/53003; it has been noted by GNATS.
 >
 > From: christos%zoulas.com@localhost (Christos Zoulas)
 > To: Mickael Viey <m.viey%wanadoo.fr@localhost>, gnats-bugs%NetBSD.org@localhost,
 > 	lib-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 > 	netbsd-bugs%netbsd.org@localhost
 > Cc:
 > Subject: Re: lib/53003: Problem with rust library using kqueue
 > Date: Sun, 11 Feb 2018 11:08:19 -0500
 >
 >   On Feb 11, 10:23am, m.viey%wanadoo.fr@localhost (Mickael Viey) wrote:
 >   -- Subject: Re: lib/53003: Problem with rust library using kqueue
 >   
 >   | Ok, the NetBSD in that I tried this code is my usual working machine,
 >   | but I will try on a VM ASAP.
 >   |
 >   | Do you know why this code fails on the stable version? (a link to a PR
 >   | by example)
 >   |
 >   | Thanks for your reply(, and sorry for the typing error on uname.)
 >   
 >   I am not sure. One thing to try is to apply the diff from
 >   of kern_event.c HEAD to the netbsd-7 branch and change f_kqueue -> f_data
 >   so that it compiles. The other thing you can do is to ktrace the binary
 >   to see where it fails. My guess is that if fails because of the following.
 >   Try it, and if it works I will ask for a pullup.
 >   
 >   christos
 >   
 >   revision 1.198
 >   date: 2017-07-01 16:07:00 -0400;  author: christos;  state: Exp;  lines: +33 -2;
 >   Provide EVFILT_WRITE; this is what FreeBSD does and go wants it.
 >   Makes go unit tests pass.
 >   
 >   
 >   Index: genfs_vnops.c
 >   ===================================================================
 >   RCS file: /cvsroot/src/sys/miscfs/genfs/genfs_vnops.c,v
 >   retrieving revision 1.197
 >   retrieving revision 1.198
 >   diff -u -r1.197 -r1.198
 >   --- genfs_vnops.c	4 Jun 2017 08:02:26 -0000	1.197
 >   +++ genfs_vnops.c	1 Jul 2017 20:07:00 -0000	1.198
 >   @@ -1,4 +1,4 @@
 >   -/*	$NetBSD: genfs_vnops.c,v 1.197 2017/06/04 08:02:26 hannken Exp $	*/
 >   +/*	$NetBSD: genfs_vnops.c,v 1.198 2017/07/01 20:07:00 christos Exp $	*/
 >    
 >    /*-
 >     * Copyright (c) 2008 The NetBSD Foundation, Inc.
 >   @@ -57,7 +57,7 @@
 >     */
 >    
 >    #include <sys/cdefs.h>
 >   -__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.197 2017/06/04 08:02:26 hannken Exp $");
 >   +__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.198 2017/07/01 20:07:00 christos Exp $");
 >    
 >    #include <sys/param.h>
 >    #include <sys/systm.h>
 >   @@ -500,6 +500,32 @@
 >    }
 >    
 >    static int
 >   +filt_genfswrite(struct knote *kn, long hint)
 >   +{
 >   +	struct vnode *vp = (struct vnode *)kn->kn_hook;
 >   +
 >   +	/*
 >   +	 * filesystem is gone, so set the EOF flag and schedule
 >   +	 * the knote for deletion.
 >   +	 */
 >   +	switch (hint) {
 >   +	case NOTE_REVOKE:
 >   +		KASSERT(mutex_owned(vp->v_interlock));
 >   +		kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 >   +		return (1);
 >   +	case 0:
 >   +		mutex_enter(vp->v_interlock);
 >   +		kn->kn_data = 0;
 >   +		mutex_exit(vp->v_interlock);
 >   +		return 1;
 >   +	default:
 >   +		KASSERT(mutex_owned(vp->v_interlock));
 >   +		kn->kn_data = 0;
 >   +		return 1;
 >   +	}
 >   +}
 >   +
 >   +static int
 >    filt_genfsvnode(struct knote *kn, long hint)
 >    {
 >    	struct vnode *vp = (struct vnode *)kn->kn_hook;
 >   @@ -530,6 +556,8 @@
 >    
 >    static const struct filterops genfsread_filtops =
 >    	{ 1, NULL, filt_genfsdetach, filt_genfsread };
 >   +static const struct filterops genfswrite_filtops =
 >   +	{ 1, NULL, filt_genfsdetach, filt_genfswrite };
 >    static const struct filterops genfsvnode_filtops =
 >    	{ 1, NULL, filt_genfsdetach, filt_genfsvnode };
 >    
 >   @@ -549,6 +577,9 @@
 >    	case EVFILT_READ:
 >    		kn->kn_fop = &genfsread_filtops;
 >    		break;
 >   +	case EVFILT_WRITE:
 >   +		kn->kn_fop = &genfswrite_filtops;
 >   +		break;
 >    	case EVFILT_VNODE:
 >    		kn->kn_fop = &genfsvnode_filtops;
 >    		break;
 >   
 Thanks, I will try to adapt the rust library to NetBSD way. I got a a 
 mio copy from github. With your indications, an kqueue documentation 
 reading I will perhaps find how I can work around this bug. In the same 
 time I will try to understand what is different in NetBSD kqueue 
 compared to FreeBSD.
 
 Best,
 
 
 Mickaël