linux-kernel - [PATCH v3 06/14] drivers/iommu: Allow IOMMU bus ops to be unregistered

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Message-Id: <20191121114918.2293-7-will@kernel.org>
Date:   Thu, 21 Nov 2019 11:49:10 +0000
From:   Will Deacon <will@...nel.org>
To:     iommu@...ts.linuxfoundation.org, linux-kernel@...r.kernel.org
Cc:     Will Deacon <will@...nel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        John Garry <john.garry@...wei.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Saravana Kannan <saravanak@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Isaac J. Manjarres" <isaacm@...eaurora.org>,
        Robin Murphy <robin.murphy@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Joerg Roedel <joro@...tes.org>
Subject: [PATCH v3 06/14] drivers/iommu: Allow IOMMU bus ops to be unregistered

'bus_set_iommu()' allows IOMMU drivers to register their ops for a given
bus type. Unfortunately, it then doesn't allow them to be removed, which
is necessary for modular drivers to shutdown cleanly so that they can be
reloaded later on.

Allow 'bus_set_iommu()' to take a NULL 'ops' argument, which clear the
ops pointer for the selected bus_type.

Signed-off-by: Will Deacon <will@...nel.org>
---
 drivers/iommu/iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 4bfecfbbe2cf..e99704c2e06b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1558,6 +1558,11 @@ int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
 {
 	int err;
 
+	if (ops == NULL) {
+		bus->iommu_ops = NULL;
+		return 0;
+	}
+
 	if (bus->iommu_ops != NULL)
 		return -EBUSY;
 
-- 
2.24.0.432.g9d3f5f5b63-goog