From: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
To: Peng Fan <van.freenix-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [RFC] iommu: arm-smmu: correct reference count
Date: Tue, 3 Nov 2015 13:17:34 +0000 [thread overview]
Message-ID: <20151103131734.GE14159@arm.com> (raw)
In-Reply-To: <1446555557-3097-1-git-send-email-van.freenix-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
On Tue, Nov 03, 2015 at 08:59:17PM +0800, Peng Fan wrote:
> iommu_group_alloc will initialize the reference count for group to 1.
> iommu_group_add_device also increase the group reference count,
> if nothing bad happends. And we need to add iommu_group_put to
> decrease the reference count for group.
>
> Signed-off-by: Peng Fan <van.freenix-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Cc: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
> Cc: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
> ---
>
> Not sure whether my understanding is correct or not. I checked rockchip-iommu.c
> exynos-iommu.c and fsl_pamu_domain.c, and they all have iommu_group_put after
> iommu_group_add_device.
Doesn't this pair up with the iommu_group_remove_device in
arm_smmu_remove_device? Are you actually seeing an issue in practice?
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC] iommu: arm-smmu: correct reference count
Date: Tue, 3 Nov 2015 13:17:34 +0000 [thread overview]
Message-ID: <20151103131734.GE14159@arm.com> (raw)
In-Reply-To: <1446555557-3097-1-git-send-email-van.freenix@gmail.com>
On Tue, Nov 03, 2015 at 08:59:17PM +0800, Peng Fan wrote:
> iommu_group_alloc will initialize the reference count for group to 1.
> iommu_group_add_device also increase the group reference count,
> if nothing bad happends. And we need to add iommu_group_put to
> decrease the reference count for group.
>
> Signed-off-by: Peng Fan <van.freenix@gmail.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> ---
>
> Not sure whether my understanding is correct or not. I checked rockchip-iommu.c
> exynos-iommu.c and fsl_pamu_domain.c, and they all have iommu_group_put after
> iommu_group_add_device.
Doesn't this pair up with the iommu_group_remove_device in
arm_smmu_remove_device? Are you actually seeing an issue in practice?
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Peng Fan <van.freenix@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
joro@8bytes.org
Subject: Re: [RFC] iommu: arm-smmu: correct reference count
Date: Tue, 3 Nov 2015 13:17:34 +0000 [thread overview]
Message-ID: <20151103131734.GE14159@arm.com> (raw)
In-Reply-To: <1446555557-3097-1-git-send-email-van.freenix@gmail.com>
On Tue, Nov 03, 2015 at 08:59:17PM +0800, Peng Fan wrote:
> iommu_group_alloc will initialize the reference count for group to 1.
> iommu_group_add_device also increase the group reference count,
> if nothing bad happends. And we need to add iommu_group_put to
> decrease the reference count for group.
>
> Signed-off-by: Peng Fan <van.freenix@gmail.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> ---
>
> Not sure whether my understanding is correct or not. I checked rockchip-iommu.c
> exynos-iommu.c and fsl_pamu_domain.c, and they all have iommu_group_put after
> iommu_group_add_device.
Doesn't this pair up with the iommu_group_remove_device in
arm_smmu_remove_device? Are you actually seeing an issue in practice?
Will
next prev parent reply other threads:[~2015-11-03 13:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-03 12:59 [RFC] iommu: arm-smmu: correct reference count Peng Fan
2015-11-03 12:59 ` Peng Fan
[not found] ` <1446555557-3097-1-git-send-email-van.freenix-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-11-03 13:17 ` Will Deacon [this message]
2015-11-03 13:17 ` Will Deacon
2015-11-03 13:17 ` Will Deacon
[not found] ` <20151103131734.GE14159-5wv7dgnIgG8@public.gmane.org>
2015-11-04 2:48 ` Peng Fan
2015-11-04 2:48 ` Peng Fan
2015-11-04 2:48 ` Peng Fan
2015-11-06 12:23 ` Will Deacon
2015-11-06 12:23 ` Will Deacon
2015-11-06 12:23 ` Will Deacon
[not found] ` <20151106122338.GI6087-5wv7dgnIgG8@public.gmane.org>
2015-11-09 5:41 ` Peng Fan
2015-11-09 5:41 ` Peng Fan
2015-11-09 5:41 ` Peng Fan
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