linux-kernel - Re: [RESEND PATCH]nbd: fix might_sleep warning on socket shutdown

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Date:	Mon, 2 May 2016 17:15:59 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Pranay Srivastava <pranjas@...il.com>
Cc:	mpa@...gutronix.de, nbd-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH]nbd: fix might_sleep warning on socket shutdown

On Mon, May 02, 2016 at 08:58:34AM +0530, Pranay Srivastava wrote:
> Hi,
> 
> Can the following patch be reviewed? I'm working on some more changes
> on top of this change,
> so it'll be really helpful if someone can review this patch and let me
> know of shortcomings/issues
> with this.
> 
> 
> On Sat, Apr 30, 2016 at 11:49 AM, Pranay Kr. Srivastava
> <pranjas@...il.com> wrote:
> > This patch fixes the warning generated when a timeout occurs
> > on the request and socket is closed from a non-sleep context
> > by
> >
> > 1. Moving the socket closing on a timeout to nbd_thread_send
> >
> > 2. Make sock lock to be a mutex instead of a spin lock, since
> >    nbd_xmit_timeout doesn't need to hold it anymore.
> >
> > 3. Move sock_shutdown outside the tx_lock in NBD_DO_IT.

Why are you doing three things in one patch?

> > ---
> >  drivers/block/nbd.c | 85 +++++++++++++++++++++++++++++++----------------------
> >  1 file changed, 50 insertions(+), 35 deletions(-)
> >
> > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> > index 31e73a7..a52cc16 100644
> > --- a/drivers/block/nbd.c
> > +++ b/drivers/block/nbd.c
> > @@ -3,7 +3,7 @@
> >   *
> >   * Note that you can not swap over this thing, yet. Seems to work but
> >   * deadlocks sometimes - you can not swap over TCP in general.
> > - *
> > + *

What did you change here?

> >   * Copyright 1997-2000, 2008 Pavel Machek <pavel@....cz>
> >   * Parts copyright 2001 Steven Whitehouse <steve@...gwyn.com>
> >   *
> > @@ -35,14 +35,14 @@
> >  #include <linux/types.h>
> >  #include <linux/debugfs.h>
> >
> > -#include <asm/uaccess.h>
> > +#include <linux/uaccess.h>

Why change this?

> >  #include <asm/types.h>
> >
> >  #include <linux/nbd.h>
> >
> >  struct nbd_device {
> >         u32 flags;
> > -       struct socket * sock;   /* If == NULL, device is not ready, yet */
> > +       struct socket *sock;    /* If == NULL, device is not ready, yet */

You are mixing "code cleanup" changes with "change the logic" changes,
please break this up into a series of patches, doing the code cleanup
_last_ as you want to fix bugs first.

thanks,

greg k-h