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From: Joerg Roedel <joro@8bytes.org>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>
Subject: Re: [PATCH] iommu: Remove functions that support private domain
Date: Fri, 15 May 2020 17:46:16 +0200	[thread overview]
Message-ID: <20200515154616.GY18353@8bytes.org> (raw)
In-Reply-To: <9d65b30a-d22e-d566-d740-601f8d638bfd@linux.intel.com>

On Fri, May 15, 2020 at 08:55:42PM +0800, Lu Baolu wrote:
> It seems that we can do like this:
> 
> [1] mutex_lock(&group->lock)
> [2] for_each_group_device(device_lock())
> [3] if (for_each_group_device(!device_is_bound()))
> 	change_default_domain()
> [4] for_each_group_device_reverse(device_unlock())
> [5] mutex_unlock(&group->lock)

The problem here is that I am pretty sure we also have:

	device_lock() /* from device/driver core code */
	-> bus_notifier()
	  -> iommu_bus_notifier()
	    -> ...
	      -> mutex_lock(&group->lock)

Which would cause lock-inversion with the above code.


	Joerg
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  reply	other threads:[~2020-05-15 15:46 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-13 22:47 [PATCH] iommu: Remove functions that support private domain Sai Praneeth Prakhya
2020-05-14 13:13 ` Joerg Roedel
2020-05-14 17:51   ` Prakhya, Sai Praneeth
2020-05-14 18:32     ` Joerg Roedel
2020-05-14 18:44       ` Prakhya, Sai Praneeth
2020-05-14 19:56         ` Joerg Roedel
2020-05-14 23:12           ` Prakhya, Sai Praneeth
2020-05-15  9:59             ` Joerg Roedel
2020-05-15 12:55               ` Lu Baolu
2020-05-15 15:46                 ` Joerg Roedel [this message]
2020-05-17  8:29                   ` Prakhya, Sai Praneeth
2020-05-25 13:56                     ` Joerg Roedel
2020-05-28 19:31                       ` Prakhya, Sai Praneeth
2020-05-15 18:35               ` Prakhya, Sai Praneeth
2020-05-15 10:01 ` Joerg Roedel

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