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From: Jason Gunthorpe <jgg@nvidia.com>
To: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: Halil Pasic <pasic@linux.ibm.com>,
	linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
	pasic@linux.vnet.ibm.com, jjherne@linux.ibm.com
Subject: Re: [PATCH] s390/vfio-ap: do not use open locks during VFIO_GROUP_NOTIFY_SET_KVM notification
Date: Mon, 5 Jul 2021 11:13:48 -0300	[thread overview]
Message-ID: <20210705141348.GN4459@nvidia.com> (raw)
In-Reply-To: <8b742188-d8a2-cf4e-e9de-0ca6f3d829b3@linux.ibm.com>

On Thu, Jul 01, 2021 at 10:28:52AM -0400, Tony Krowiak wrote:

> > I think Jason was talking about open coding locks in general.
> 
> That may be so, but his comments were in support of his
> statement that the  mutex + wait_queue did not resolve
> the issue reported vai the lockdep splat because it turned
> off lockdep.

Rgiht, if this used to be proper locks and lockdep complained then
whatever potential deadlock it found is not magically removed by going
to a wait_queue. It just removes the lockdep annotations that would
identify the issue early.

This is why people should not open code locks, it completely defeats
lockdep. That alone is merit enough for this patch.

Jason

  reply	other threads:[~2021-07-05 14:13 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-25 22:07 [PATCH] s390/vfio-ap: do not use open locks during VFIO_GROUP_NOTIFY_SET_KVM notification Tony Krowiak
2021-06-28 17:34 ` Jason Gunthorpe
2021-06-28 18:20   ` Tony Krowiak
2021-06-28 18:22     ` Jason Gunthorpe
2021-06-28 18:27       ` Tony Krowiak
2021-06-28 20:29 ` Halil Pasic
2021-06-30 14:31   ` Tony Krowiak
2021-06-30 22:39     ` Halil Pasic
2021-07-01 14:28       ` Tony Krowiak
2021-07-05 14:13         ` Jason Gunthorpe [this message]
2021-07-06 13:39           ` Tony Krowiak
2021-07-06 13:49             ` Jason Gunthorpe
2021-07-06 22:43               ` Tony Krowiak
2021-06-29 13:21 ` Jason J. Herne
2021-06-30 11:55   ` Jason Gunthorpe

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