linux-kernel - [RFC PATCH 08/14] IOMMU: iommu_unique_seq

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Date:	Mon,  2 Apr 2012 19:19:35 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Len Brown <len.brown@...el.com>,
	Jiang Liu <jiang.liu@...wei.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>, x86 <x86@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: [RFC PATCH 08/14] IOMMU: iommu_unique_seq_id()

So for hot-remove/hot-add will reuse seq_id.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 drivers/iommu/dmar.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index fde4991..043192e 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -707,13 +707,23 @@ int __init detect_intel_iommu(void)
 	return ret ? 1 : -ENODEV;
 }
 
+static DECLARE_BITMAP(iommu_allocated, 1024);
+
+static int iommu_unique_seq_id(void)
+{
+	int id;
+
+	id = find_first_zero_bit(iommu_allocated, 1024);
+	__set_bit(id, iommu_allocated);
+
+	return id;
+}
 
 int alloc_iommu(struct dmar_drhd_unit *drhd)
 {
 	struct intel_iommu *iommu;
 	int map_size;
 	u32 ver;
-	static int iommu_allocated = 0;
 	int agaw = 0;
 	int msagaw = 0;
 
@@ -726,7 +736,7 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 	if (!iommu)
 		return -ENOMEM;
 
-	iommu->seq_id = iommu_allocated++;
+	iommu->seq_id = iommu_unique_seq_id();
 	sprintf (iommu->name, "dmar%d", iommu->seq_id);
 
 	iommu->reg = ioremap(drhd->reg_base_addr, VTD_PAGE_SIZE);
@@ -790,6 +800,7 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
  err_unmap:
 	iounmap(iommu->reg);
  error:
+	__clear_bit(iommu->seq_id, iommu_allocated);
 	kfree(iommu);
 	return -1;
 }
@@ -803,6 +814,7 @@ void free_iommu(struct intel_iommu *iommu)
 
 	if (iommu->reg)
 		iounmap(iommu->reg);
+	__clear_bit(iommu->seq_id, iommu_allocated);
 	kfree(iommu);
 }
 
-- 
1.7.7

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